COVID-19 VaccineNCT05004740
Is COVID-19 Transmitted Through Human Milk? Implications for Breastfeeding and Human Milk Banking-Study 1c
An observational study of COVID-19 Vaccine and Breastmilk, run by Deborah O'Connor at 1 site in Canada.
Trial summary
This will be a prospective observational study of lactating mothers who are planning to, have scheduled or have received vaccination against SARS-COV-2 (COVID-19 vaccine). Mothers may have delivered at Mount Sinai Hospital or may be from the general public recruited by social media or word of mouth. Read more about this study
- Who is it for?
- Any ageHealthy volunteers can take part
- Conditions the study is for
- COVID-19 Vaccine, Breastmilk
- What is being tested?
- Vaccinated Pregnant or Lactating persons
- Type of treatment
- Vaccines
- How many people
- 78 participants
- Where
- 1 siteCanada
- Study dates
- 17 Jan 2021to 27 Apr 2023
- Phase
- Observational
- Are there results?
- None posted in the registry
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 Any age
- All sexes
- Healthy volunteers accepted
- Child, Adult, Older adult
Study population: Community sample
Who may be able to join
- lactating birthing persons from the general public or Sinai Health System
Who cannot join
- None
Trial locations and contacts
1 site in 1 country.
About this study
This will be a prospective observational study of lactating mothers who are planning to, have scheduled or have received vaccination against SARS-COV-2 (COVID-19 vaccine). Mothers may have delivered at Mount Sinai Hospital or may be from the general public recruited by social media or word of mouth. As the study participants will be lactating mothers, they will not be under the care of the investigators. Due to lack of information, we are unsure of an appropriate sample size but envision we will recruit at least 10 women each immunized with the approved mRNA vaccines (e.g. Pfizer-BioNTech and Moderna COVID-19 vaccines) and in the future at least two other vaccines (e.g. Oxford-AstraZeneca) as they are approved and become available. Milk samples will be analyzed for the presence of antibody to SARS-CoV-2 using the Anti-SARS-CoV-2 ELISA (IgG and IgA). These analyses will be conducted in the Department of Microbiology at Sinai Health following validation of the procedures in human milk.
- Conditions
- COVID-19 Vaccine, Breastmilk
- Being tested
- Vaccinated Pregnant or Lactating persons
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Vaccinated Pregnant or Lactating personsOther
vaccinated lactating persons from Sinai Health System or the general public
| Study group | Role | What they receive |
|---|---|---|
| Lactating birthing persons delivering at Sinai Health System or from the general population | Not described Receives: Other: Vaccinated Pregnant or Lactating persons |
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of participants with and timing of SARS-CoV-2 specific antibodies in breastmilk post-vaccination
Measured: Week prior to first dose of vaccination and until 4 weeks following the second dose of vaccination.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Aug 2021
- Study start17 Jan 2021
- Primary completion27 Apr 2022
- Study completion27 Apr 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for COVID-19 VaccineStudies of the same condition, open and under way.
- 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
- Prospective
- Enrolment
- 78 participants (actual)
Sponsor and investigators
- Lead sponsor
- Deborah O'Connor
- Sponsor type
- University, hospital or other
- Collaborators
- University of Toronto, Sinai Health System
- Responsible party
- Sponsor-investigator, Deborah O'Connor, The Hospital for Sick Children
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05004740
- Sponsor's protocol ID
- 39373-c
- Status last verified
- Jun 2025
- First submitted
- 11 Aug 2021
- Last updated
- 6 Jun 2025
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Ismail S, Unger S, Budylowski P, Poutanen S, Yau Y, Jenkins C, Anwer S, Christie-Holmes N, Kiss A, Mazzulli T, Johnstone J, McGeer A, Whittle W, Parvez B, Gray-Owen SD, Stone D, O'Connor DL. SARS-CoV-2 antibodies and their neutralizing capacity against live virus in human milk after COVID-19 infection and vaccination: prospective cohort studies. Am J Clin Nutr. 2024 Feb;119(2):485-495. doi: 10.1016/j.ajcnut.2023.10.008. Epub 2023 Dec 14.
PubMed 38309831
Study at a glance
From the registry record, last updated by the sponsor on 6 Jun 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Is COVID-19 Transmitted Through Human Milk? Implications for Breastfeeding and Human Milk Banking-Study 1c
- ClinicalTrials.gov ID
- NCT05004740
- Acronym / sponsor ID
- 39373-c
- Conditions
- COVID-19 Vaccine, Breastmilk
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 78 participants (actual)
- Lead sponsor
- Deborah O'ConnorUniversity, hospital or other
- Collaborators
- University of Toronto, Sinai Health System
- Study start
- 17 Jan 2021 (actual)
- Primary completion
- 27 Apr 2022 (actual)
- Study completion
- 27 Apr 2023 (actual)
- First posted
- 13 Aug 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This will be a prospective observational study of lactating mothers who are planning to, have scheduled or have received vaccination against SARS-COV-2 (COVID-19 vaccine). Mothers may have delivered at Mount Sinai Hospital or may be from the general public recruited by social media or word of mouth. As the study participants will be lactating mothers, they will not be under the care of the investigators. Due to lack of information, we are unsure of an appropriate sample size but envision we will recruit at least 10 women each immunized with the approved mRNA vaccines (e.g. Pfizer-BioNTech and Moderna COVID-19 vaccines) and in the future at least two other vaccines (e.g. Oxford-AstraZeneca) as they are approved and become available. Milk samples will be analyzed for the presence of antibody to SARS-CoV-2 using the Anti-SARS-CoV-2 ELISA (IgG and IgA). These analyses will be conducted in the Department of Microbiology at Sinai Health following validation of the procedures in human milk.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Lactating birthing persons delivering at Sinai Health System or from the general population | – | Other: Vaccinated Pregnant or Lactating persons |
Who may qualify
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult, Older adult
- Study population
- Community sample
Key inclusion criteria (1 listed)
- lactating birthing persons from the general public or Sinai Health System
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 |
|---|---|---|
| Vaccinated Pregnant or Lactating personsvaccinated lactating persons from Sinai Health System or the general public | Other | Lactating birthing persons delivering at Sinai Health System or from the general population |
Primary outcome
Number of participants with and timing of SARS-CoV-2 specific antibodies in breastmilk post-vaccination
Time frame: Week prior to first dose of vaccination and until 4 weeks following the second dose of vaccination.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Jun 2025.
- Background: PubMed 38309831Ismail S, Unger S, Budylowski P, Poutanen S, Yau Y, Jenkins C, Anwer S, Christie-Holmes N, Kiss A, Mazzulli T, Johnstone J, McGeer A, Whittle W, Parvez B, Gray-Owen SD, Stone D, O'Connor DL. SARS-CoV-2 antibodies and their neutralizing capacity against live virus in human milk after COVID-19 infection and vaccination: prospective cohort studies. Am J Clin Nutr. 2024 Feb;119(2):485-495. doi: 10.1016/j.ajcnut.2023.10.008. Epub 2023 Dec 14.
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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.
The record lists no contact. Use the official record to reach the sponsor.
1 site 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 Vaccine and Breastmilk, run by Deborah O'Connor at 1 site in Canada.
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 1 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 6 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 1 site in Canada. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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 with and timing of SARS-CoV-2 specific antibodies in breastmilk post-vaccination (time frame: Week prior to first dose of vaccination and until 4 weeks following the second dose of vaccination.). 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 NCT05004740, 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 6 Jun 2025.