A Study of COVID-19 Patients Receiving Treatment With Nirmatrelvir; Ritonavir in the Kingdom of Saudi Arabia

An observational study of Covid-19, run by Pfizer at 3 sites in Saudi Arabia.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Trial summary

The aim of this study is to describe the baseline demographic, clinical characteristics, and Healthcare Resource Use (HCRU) of adult (≥18 years) COVID-19 patients who have been prescribed nirmatrelvir, ritonavir treatment. Read more about this study

Who is it for?: Ages 18 years and older
Conditions the study is for: Covid-19
What is being tested?: nirmatrelvir, ritonavir
How many people: 250 participants
Where: 3 sitesSaudi Arabia
Study dates: 17 Oct 2023to 9 Apr 2024
Phase: Observational
Are there results?: Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 18 years and older
All sexes
No healthy volunteers
Adult, Older adult

Study population: The study will involve collection of pre-defined, structured data retrospectively from medical records (electronic and/or paper if necessary) of patients who meet the study eligibility criteria and who have been prescribed nirmatrelvir, ritonavir treatment within a 15-month lookback period from the date of site initiation (Cohort 1). The lookback period will span from 01 April 2022 to 30 June 2023. Data abstracted from patients' medical records will include patient demographics and clinical characteristics at index date (defined as the date of nirmatrelvir, ritonavir treatment prescribing), in addition to patients' HCRU during the 30-day period post-index date.

Who may be able to join

Confirmed COVID-19 infection during the study observation period
Nirmatrelvir, ritonavir written prescription

Who cannot join

None

Trial locations and contacts

3 sites in 1 country.

Saudi Arabia3 sites

King Faisal Specialist Hospital & research center - Jeddah
Jeddah, 21499
King Abdulaziz Medical City
Riyadh, 11426
King Faisal Specialist Hospital and Research Center
Riyadh

Other trials in Saudi Arabia

About this study

Official title: A Retrospective Observational Non-Interventional Study (NIS) to Assess Patient Characteristics and Healthcare Resource Use (HCRU) Among COVID-19 Patients Receiving Treatment With Nirmatrelvir; Ritonavir (PAXLOVID TM) in the Kingdom of Saudi Arabia (KSA).

Conditions: Covid-19
Being tested: nirmatrelvir, ritonavir
Keywords: Paxlovid, Saudi Arabia
Medical subject headings: COVID-19

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

nirmatrelvir, ritonavirDrug
Also called Paxlovid
single cohort

Study groups in NCT06016556
Study group	Role	What they receive
Patients receiving Nirmatrelvir; Ritonavir (PAXLOVID)		Adult COVID-19 patients' HCRU within the 30-day period following nirmatrelvir, ritonavir prescription. Receives: Drug: nirmatrelvir, ritonavir

What is being measured

The primary outcome is the main question the study is designed to answer.

Number of Participants Classified According to Education Level at Index Date
Education level classification: no formal education, primary school, secondary school, undergraduate university degree, master's degree and Doctor of Philosophy (PhD) or doctorate. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Classified According to Employment Status at Index Date
Employment status classification: full-time employment, part-time employment, homemaker, retired, student, disabled/too ill to work, and unemployed. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Height at Index Date
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Weight at Index Date
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Body Mass Index (BMI) at Index Date
BMI was calculated based on the reported weight and height in the unit of kilograms over squared meters (kg/m^2). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Classified According to Smoking Status at Index Date
Smoking status classification: current smoker, former smoker and never smoker. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Had at Least 1 Pre-existing Comorbidity at Index Date
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Had at Least 1 Concomitant Medication for Comorbidities at Index Date
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants With COVID-19 Infection During the Last 6 Months Prior to Index Date
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: During 6 months prior to index date, information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Duration Between Last COVID-19 Infection and Index Date
Duration (in months) between COVID-19 infection in last 6 months prior to index date and index date was reported in this outcome measure. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: From 6 months prior to index date up to index date, information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Had Previously Received at Least 1 Dose of Any COVID-19 Vaccine
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: Historic information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Classified According to the Type of COVID-19 Vaccine Received Previously
One participant could have received more than one type of vaccine. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: Historic information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Duration Between Previous COVID-19 Vaccination Date and Index Date
Duration (in months) between vaccination date and index date was calculated as (index date - date of first covid-19 vaccination date)/30.42. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: From date of first COVID-19 vaccination to index date, information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Classified According to Total Number of Previous COVID-19 Vaccine Doses Taken
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: Historic information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Classified According to Dose of Nirmatrelvir/Ritonavir Received at Index Date
Classification: 1) Nirmatrelvir at a dose of 300 milligrams (mg), as 2 split doses of 150 mg and Ritonavir at a dose of 100 mg; 2) Other: Nirmatrelvir at a dose of 150 mg, and Ritonavir at a dose of 100 mg. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Classified According to Frequency of Dosing of Nirmatrelvir/Ritonavir (PAXLOVIDTM) at Index Date
Classification: 1) Nirmatrelvir at a dose of 300 mg, as 2 split doses of 150 mg and Ritonavir at a dose of 100 mg; 2) Other: Nirmatrelvir at a dose of 150 mg, and Ritonavir at a dose of 100 mg. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Classified According to Dispensed Type of Nirmatrelvir/Ritonavir (PAXLOVIDTM) at Index Date
Classification of dispensed type: blister, box, tablets. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Classified According to Medications Used to Treat COVID-19 Infection at Index Date
Number of participants classified according to medications (apart from Nirmatrelvir/Ritonavir [PAXLOVIDTM]) used to treat COVID-19 infection at index date were reported in this outcome measure. A participant may receive more than one medication to treat COVID-19 infection. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Were Hospitalized at Index Date
In this outcome measure those number of participants are reported who were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM) while they were hospitalized (related or non-related to COVID-19). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: Information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Were Hospitalized Due to COVID-19 at Index Date
In this outcome measure those number of participants are reported who were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM) while they were hospitalized (related to COVID-19). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: Information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Length of Hospitalization Stay Due to COVID-19 at Index Date
Length of hospitalization stay was measured in days from day of hospitalization (related to COVID-19) till index date. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: From day of hospitalization till index date, information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants With Intensive Care Unit (ICU) Admission at Index Date
In this outcome measure those number of participants are reported who were admitted to ICU while they were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: Information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Length of ICU Stay Due to COVID-19 at Index Date
Length of ICU stay was measured in days from day of ICU admission till index date. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: From day of ICU admission till index date, information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Were on Supplemental Oxygen Use at Index Date
In this outcome measure those number of participants are reported who were on supplemental oxygen use when they were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Were on Vasopressor Use at Index Date
In this outcome measure those number of participants are reported who were on vasopressor use when they were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants With Intubation at Index Date
In this outcome measure those number of participants are reported who were intubated when they were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants With Outpatient Visits at Index Date
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Had Emergency Room (ER) Visits Due to COVID-19 at Index Date
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: At index date; retrospective data was evaluated during approximately 6 months of this study

Secondary outcomes (12)

Number of Participants Who Were Hospitalized During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Were Hospitalized Due to COVID-19 During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Length of Hospitalization Stay Due to COVID-19 During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants With ICU Admission During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Length of ICU Stay Due to COVID-19 During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Were on Supplemental Oxygen Use During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Were on Vasopressor Use During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants With Intubation During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Had Outpatient Visits During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Had ER Visits Due to COVID-19 During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Classified According to COVID-19 Polymerase Chain Reaction (PCR) and Antigen Test Results During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Time to Negative COVID-19 Test During the 30-day Post-Index Period
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period). Time to negative COVID-19 test was assessed from index date till participant tested negative for COVID-19 during 30 days post index period.
Measured: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

17 Oct 20239 Apr 2024

First posted29 Aug 2023
Study start17 Oct 2023
Primary completion9 Apr 2024
Study completion9 Apr 2024

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (1)Papers the sponsor has linked to this study.
Other trials for Covid-19Studies of the same condition, open and under way.
More trials run by PfizerThe sponsor's other registered studies.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Observational
Observational model: Cohort
Time perspective: Retrospective
Enrolment: 250 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06016556
Sponsor's protocol ID: C4671054
Other IDs: NCT06016556
Status last verified: May 2025
First submitted: 25 Aug 2023
Last updated: 5 Jun 2025
Results posted: Yes, on ClinicalTrials.gov
Individual data sharing: No: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.

Publications

Alraddadi BM, Almaghrabi RS, Bosaeed M, Kamal M, Hassanien A, Hammam H, Zanotti G, Ikizler BK, d'Hellencourt FL, Spinardi JR, Wang L, Kyaw MH. Patient Characteristics and Healthcare Resource Use among Patients With COVID-19 Receiving Treatment with Nirmatrelvir/Ritonavir (PAXLOVID) in the Kingdom of Saudi Arabia. Pulm Ther. 2026 Jun;12(2):617-635. doi: 10.1007/s41030-026-00360-3. Epub 2026 May 19.
PubMed 42156669

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

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Study at a glance

From the registry record, last updated by the sponsor on 5 Jun 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A Retrospective Observational Non-Interventional Study (NIS) to Assess Patient Characteristics and Healthcare Resource Use (HCRU) Among COVID-19 Patients Receiving Treatment With Nirmatrelvir; Ritonavir (PAXLOVID TM) in the Kingdom of Saudi Arabia (KSA).
ClinicalTrials.gov ID: NCT06016556
Acronym / sponsor ID: C4671054
Conditions: Covid-19
Keywords: Paxlovid, Saudi Arabia
Study type: Observational
Recruitment status: Completed
Enrolment: 250 participants (actual)
Lead sponsor: PfizerIndustry (pharma, biotech, devices)
Study start: 17 Oct 2023 (actual)
Primary completion: 9 Apr 2024 (actual)
Study completion: 9 Apr 2024 (actual)
First posted: 29 Aug 2023 (actual)
Results: Posted 29 Apr 2025

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Study design

Observational model: Cohort
Time perspective: Retrospective
Number of arms: 1

Arm	Type	Receives
Patients receiving Nirmatrelvir; Ritonavir (PAXLOVID)	–	Drug: nirmatrelvir, ritonavirAdult COVID-19 patients' HCRU within the 30-day period following nirmatrelvir, ritonavir prescription.

Who may qualify

Ages: 18 years and older
Sex: All
Healthy volunteers: Not accepted
Age groups: Adult, Older adult
Study population: The study will involve collection of pre-defined, structured data retrospectively from medical records (electronic and/or paper if necessary) of patients who meet the study eligibility criteria and who have been prescribed nirmatrelvir, ritonavir treatment within a 15-month lookback period from the date of site initiation (Cohort 1). The lookback period will span from 01 April 2022 to 30 June 2023. Data abstracted from patients' medical records will include patient demographics and clinical characteristics at index date (defined as the date of nirmatrelvir, ritonavir treatment prescribing), in addition to patients' HCRU during the 30-day period post-index date.

Key inclusion criteria (2 listed)

Confirmed COVID-19 infection during the study observation period
Nirmatrelvir, ritonavir written prescription

Key exclusion criteria (1 listed)

None

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
nirmatrelvir, ritonavirAlso: Paxlovidsingle cohort	Drug	Patients receiving Nirmatrelvir; Ritonavir (PAXLOVID)

Primary outcome

Number of Participants Classified According to Education Level at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Education level classification: no formal education, primary school, secondary school, undergraduate university degree, master's degree and Doctor of Philosophy (PhD) or doctorate. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Classified According to Employment Status at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Employment status classification: full-time employment, part-time employment, homemaker, retired, student, disabled/too ill to work, and unemployed. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Height at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Weight at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Body Mass Index (BMI) at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
BMI was calculated based on the reported weight and height in the unit of kilograms over squared meters (kg/m^2). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Classified According to Smoking Status at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Smoking status classification: current smoker, former smoker and never smoker. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Who Had at Least 1 Pre-existing Comorbidity at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Who Had at Least 1 Concomitant Medication for Comorbidities at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants With COVID-19 Infection During the Last 6 Months Prior to Index Date
Time frame: During 6 months prior to index date, information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Duration Between Last COVID-19 Infection and Index Date
Time frame: From 6 months prior to index date up to index date, information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Duration (in months) between COVID-19 infection in last 6 months prior to index date and index date was reported in this outcome measure. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Who Had Previously Received at Least 1 Dose of Any COVID-19 Vaccine
Time frame: Historic information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Classified According to the Type of COVID-19 Vaccine Received Previously
Time frame: Historic information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
One participant could have received more than one type of vaccine. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Duration Between Previous COVID-19 Vaccination Date and Index Date
Time frame: From date of first COVID-19 vaccination to index date, information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Duration (in months) between vaccination date and index date was calculated as (index date - date of first covid-19 vaccination date)/30.42. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Classified According to Total Number of Previous COVID-19 Vaccine Doses Taken
Time frame: Historic information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Classified According to Dose of Nirmatrelvir/Ritonavir Received at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Classification: 1) Nirmatrelvir at a dose of 300 milligrams (mg), as 2 split doses of 150 mg and Ritonavir at a dose of 100 mg; 2) Other: Nirmatrelvir at a dose of 150 mg, and Ritonavir at a dose of 100 mg. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Classified According to Frequency of Dosing of Nirmatrelvir/Ritonavir (PAXLOVIDTM) at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Classification: 1) Nirmatrelvir at a dose of 300 mg, as 2 split doses of 150 mg and Ritonavir at a dose of 100 mg; 2) Other: Nirmatrelvir at a dose of 150 mg, and Ritonavir at a dose of 100 mg. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Classified According to Dispensed Type of Nirmatrelvir/Ritonavir (PAXLOVIDTM) at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Classification of dispensed type: blister, box, tablets. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Classified According to Medications Used to Treat COVID-19 Infection at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Number of participants classified according to medications (apart from Nirmatrelvir/Ritonavir [PAXLOVIDTM]) used to treat COVID-19 infection at index date were reported in this outcome measure. A participant may receive more than one medication to treat COVID-19 infection. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Who Were Hospitalized at Index Date
Time frame: Information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
In this outcome measure those number of participants are reported who were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM) while they were hospitalized (related or non-related to COVID-19). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Who Were Hospitalized Due to COVID-19 at Index Date
Time frame: Information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
In this outcome measure those number of participants are reported who were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM) while they were hospitalized (related to COVID-19). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Length of Hospitalization Stay Due to COVID-19 at Index Date
Time frame: From day of hospitalization till index date, information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Length of hospitalization stay was measured in days from day of hospitalization (related to COVID-19) till index date. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants With Intensive Care Unit (ICU) Admission at Index Date
Time frame: Information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
In this outcome measure those number of participants are reported who were admitted to ICU while they were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Length of ICU Stay Due to COVID-19 at Index Date
Time frame: From day of ICU admission till index date, information obtained at index date; retrospective data was evaluated during approximately 6 months of this study
Length of ICU stay was measured in days from day of ICU admission till index date. Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Who Were on Supplemental Oxygen Use at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
In this outcome measure those number of participants are reported who were on supplemental oxygen use when they were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Who Were on Vasopressor Use at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
In this outcome measure those number of participants are reported who were on vasopressor use when they were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants With Intubation at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
In this outcome measure those number of participants are reported who were intubated when they were prescribed Nirmatrelvir/Ritonavir (PAXLOVIDTM). Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants With Outpatient Visits at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).
Number of Participants Who Had Emergency Room (ER) Visits Due to COVID-19 at Index Date
Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study
Index date was defined as the date of nirmatrelvir, ritonavir (PAXLOVIDTM) treatment prescription, which could be any day between 1-Apr-2022 to 30-Jun-2023 (15-month look back period).

12 secondary outcomes

Number of Participants Who Were Hospitalized During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Were Hospitalized Due to COVID-19 During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Length of Hospitalization Stay Due to COVID-19 During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants With ICU Admission During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Length of ICU Stay Due to COVID-19 During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Were on Supplemental Oxygen Use During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Were on Vasopressor Use During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants With Intubation During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Had Outpatient Visits During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Who Had ER Visits Due to COVID-19 During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Number of Participants Classified According to COVID-19 Polymerase Chain Reaction (PCR) and Antigen Test Results During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study
Time to Negative COVID-19 Test During the 30-day Post-Index Period
Time frame: 30-day post index date; retrospective data was evaluated during approximately 6 months of this study

Results and safety

Results posted to the registry on 29 Apr 2025, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
All Participants	248	248

Primary outcome: Number of Participants Classified According to Education Level at Index Date

Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study. Count of participants. Unit: Participants

Measure	All Participants n = 140
No formal education	32
Primary school	1
Secondary school	22
Undergraduate university degree	85
Master's degree	0
PhD or doctorate	0

Population analysed: Analysis population included all eligible participants whose data were included and observed in this study. Here, "Overall Number of Participants Analyzed" signifies those number of participants who had non-missing values and were evaluable for this outcome measure.

Primary outcome: Number of Participants Classified According to Employment Status at Index Date

Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study. Count of participants. Unit: Participants

Measure	All Participants n = 150
Full-time employment	41
Part-time employment	1
Homemaker	10
Retired	42
Student	11
Disabled/too ill to work	3
Unemployed	42

Primary outcome: Height at Index Date

Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study. Mean (Standard Deviation). Unit: Meters

Measure	All Participants n = 240
Value	1.62 (0.10)

Population analysed: Analysis population included all eligible participants whose data were included and observed in this study. Here, ''Overall Number of Participants Analyzed'' signifies number of participants who had non-missing values and were evaluable for this outcome measure.

Primary outcome: Weight at Index Date

Time frame: At index date; retrospective data was evaluated during approximately 6 months of this study. Mean (Standard Deviation). Unit: Kilograms

Measure	All Participants n = 242
Value	74.13 (18.81)

12 secondary outcomes are reported in the full results.

Adverse events

Time frame: From Index date up to 30 days post index date (maximum up to 15 months); data was retrospectively evaluated over approximately 6 months of this study. Other adverse events reported at 0% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
All Participants	2 of 248 (0.8%)	0 of 248 (0%)	0 of 248

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 5 Jun 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Derived from this study: PubMed 42156669Alraddadi BM, Almaghrabi RS, Bosaeed M, Kamal M, Hassanien A, Hammam H, Zanotti G, Ikizler BK, d'Hellencourt FL, Spinardi JR, Wang L, Kyaw MH. Patient Characteristics and Healthcare Resource Use among Patients With COVID-19 Receiving Treatment with Nirmatrelvir/Ritonavir (PAXLOVID) in the Kingdom of Saudi Arabia. Pulm Ther. 2026 Jun;12(2):617-635. doi: 10.1007/s41030-026-00360-3. Epub 2026 May 19.
To obtain contact information for a study center near you, click here.Link provided by the sponsor.
Individual participant dataSharing planned: No. Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical_trials/trial_data_and_results/data_requests.

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Pfizer CT.gov Call Center study director

Pfizer

3 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

An observational study of Covid-19, run by Pfizer at 3 sites in Saudi Arabia.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 2 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 5 Jun 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 3 sites in Saudi Arabia. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

Yes. Results are posted in the registry (first posted 29 Apr 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Number of Participants Classified According to Education Level at Index Date (time frame: At index date; retrospective data was evaluated during approximately 6 months of this study). The study lists 28 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06016556, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 5 Jun 2025.