Post InfluenzaNCT02511002
Long-term Observation of Hemagglutinin and Neuraminidase Inhibition Antibody Titers After Influenza Challenge
An observational study of Post Influenza, run by National Institute of Allergy and Infectious Diseases (NIAID) at 1 site in United States.
Trial summary
Background: Influenza is a common viral infection, but it can be deadly for some people. Researchers want to learn more about how the body fights this virus. They want to study this in people who have recently been infected with influenza. They hope this can help them create more effective influenza vaccines. Read more about this study
- Who is it for?
- Ages 18 to 120 yearsHealthy volunteers can take part
- Conditions the study is for
- Post Influenza
- How many people
- 200 participants
- Where
- 1 siteUnited States
- Study dates
- 17 Jul 2015to 12 May 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
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 to 120 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Study population: Healthy volunteers after influenza challenge and patients after natural influenza infection
Who may be able to join
- Completion of participation in an LID Clinical Studies Unit influenza challenge study or current or prior participation in an LID natural history study.
- Willing to have samples stored for future research.
- CO-ENROLLMENT GUIDELINES:
- Participants may be co-enrolled in other research studies. This will be addressed on a case-by-case basis with the approval of the principal investigator (PI) or associate investigator.
- If a participant enrolls in another influenza challenge study, the participant will be removed from this study. The participant can re-enroll in this study after completion of the influenza challenge study and will be followed for two years following completion of the most recent influenza challenge study.
Who cannot join
- Any condition or event that, in the PI s opinion, may substantially increase the risk associated with study participation or compromise the study s scientific objectives. Conditions that exclude a subject are considered to be unlikely, but an example would include a newly diagnosed medical condition that may alter a participant s immune system and make it unsafe to obtain scheduled blood samples for research purposes.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site
National Institutes of Health Clinical Center
Bethesda, Maryland, 20892
About this study
Official title: Long-Term Observation of Hemagglutinin and Neuraminidase Inhibition Antibody Titers After Influenza Challenge
Background:
- Influenza is a common viral infection, but it can be deadly for some people. Researchers want to learn more about how the body fights this virus. They want to study this in people who have recently been infected with influenza. They hope this can help them create more effective influenza vaccines.
Read more
Objective:
- To learn about long-term changes in the body s immune system after influenza infection.
Eligibility:
- People who have completed a previous LID Clinical Studies Unit influenza challenge study or current or prior participation in an LID natural history study and are willing to have samples stored for future research.
Design:
- Eligible participants will be asked to visit the clinic every 3 months for 2 years.
- During each visit, participants will have blood drawn from an arm vein using a needle and a syringe and a nasal sample.
- Participants will have a medical history and physical exam and vital signs performed. This will include blood pressure, heart rate, breathing rate, temperature, weight, and finger-measured blood oxygen. They will answer questions about any medicines taken and possible recent illnesses.
- If participants have symptoms of influenza, they may have an additional sample taken from the nose.
- Participants will complete a health questionnaire once a month on a secure website. Participants may also give their responses over the telephone....
Read the detailed description
Circulating anti-influenza antibodies are an important factor in predicting clinical illness and severity in those infected with influenza. Specific antibodies against influenza include proteins targeting hemagglutinin (HA) and neuraminidase (NA). Lifelong immunity does not occur with influenza, either from natural infection or from vaccination. Due to the antigenic variation of Influenza A, individuals may become infected multiple times with the same subtype of influenza and even with the same strain. In the setting of natural infection and vaccination, antibody titer levels can persist initially, but then wane over time.
In our previous challenge studies, measurements of antibody responses have been focused solely on the acute infection period up to 2 months after initial infection. Long-term changes in immunity have not been investigated. The challenge setting gives us the unique ability to follow individuals from a specific, known and well-characterized exposure/illness to measure long-term changes in antibody titers from a pre-exposure baseline. This study could offer unique insight into how anti-influenza antibody titers change over time naturally and in response to other infections and life events. This type of controlled study has never been done and we believe monitoring titers long-term will help us better understand protective correlates of influenza.
In this natural history study, we will follow individuals who have undergone influenza challenge or have been naturally infected with influenza to evaluate changes in anti-influenza antibody titers over a 2-year period. Subjects will be followed for symptoms of influenza-like illness (ILI) and other changes in clinical status through quarterly clinical evaluations with blood draws. Monthly questionnaires will be used to follow subjects in between visits.
- Conditions
- Post Influenza
- Keywords
- Natural History, Longitudinal Observation, Influenza Like Infection (ILI), Immunity, Flu
- Medical subject headings
- Influenza, Human
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| 1 | Post influenza infection |
What is being measured
The primary outcome is the main question the study is designed to answer.
To characterize the timing of peak antibody response to hemagglutinin (HA) and neuraminidase (NA) post influenza challenge or after natural infection To evaluate the long-term variability of hemagglutinin inhibition (HAI) and neuraminidase inhib...
Trend of HAI titer over multiple time points Trend of NAI titer over multiple time points
Measured: 2 years
Secondary outcomes (1)
To correlate changes in clinical status such as influenza-like illness (ILI) or vaccinations with changes in antibody titers and other immune measures
Change in HAI titer before and after change in clinical status Change in NAI titer before and after change in clinical status
Measured: 2 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Jul 2015 (estimated)
- Study start17 Jul 2015
- Primary completion12 May 2027 (estimated)
- Study completion12 May 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (3)Papers the sponsor has linked to this study.
- Other trials for Post InfluenzaStudies of the same condition, open and under way.
- More trials run by National Institute of Allergy and Infectious Diseases (NIAID)The 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
- Prospective
- Enrolment
- 200 participants (estimated)
Sponsor and investigators
- Sponsor type
- US National Institutes of Health
- Responsible party
- Sponsor
- Investigators
- Alison Han, M.D., Principal investigator, National Institute of Allergy and Infectious Diseases (NIAID)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT02511002
- Sponsor's protocol ID
- 150154
- Other IDs
- 15-I-0154
- Status last verified
- 10 Jul 2026
- First submitted
- 28 Jul 2015
- Last updated
- 29 Oct 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Publications
Grohskopf LA, Olsen SJ, Sokolow LZ, Bresee JS, Cox NJ, Broder KR, Karron RA, Walter EB; Centers for Disease Control and Prevention. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP) -- United States, 2014-15 influenza season. MMWR Morb Mortal Wkly Rep. 2014 Aug 15;63(32):691-7.
PubMed 25121712Thompson WW, Weintraub E, Dhankhar P, Cheng PY, Brammer L, Meltzer MI, Bresee JS, Shay DK. Estimates of US influenza-associated deaths made using four different methods. Influenza Other Respir Viruses. 2009 Jan;3(1):37-49. doi: 10.1111/j.1750-2659.2009.00073.x.
PubMed 19453440Cox RJ. Correlates of protection to influenza virus, where do we go from here? Hum Vaccin Immunother. 2013 Feb;9(2):405-8. doi: 10.4161/hv.22908. Epub 2013 Jan 4.
PubMed 23291930
Study at a glance
From the registry record, last updated by the sponsor on 29 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Long-Term Observation of Hemagglutinin and Neuraminidase Inhibition Antibody Titers After Influenza Challenge
- ClinicalTrials.gov ID
- NCT02511002
- Acronym / sponsor ID
- 150154
- Conditions
- Post Influenza
- Keywords
- Natural History, Longitudinal Observation, Influenza Like Infection (ILI), Immunity, Flu
- Study type
- Observational
- Recruitment status
- Enrolling by invitation
- Enrolment
- 200 participants (estimated)
- Lead sponsor
- National Institute of Allergy and Infectious Diseases (NIAID)US National Institutes of Health
- Study start
- 17 Jul 2015 (actual)
- Primary completion
- 12 May 2027 (estimated)
- Study completion
- 12 May 2027 (estimated)
- First posted
- 29 Jul 2015 (estimated)
- 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.
Background:
- Influenza is a common viral infection, but it can be deadly for some people. Researchers want to learn more about how the body fights this virus. They want to study this in people who have recently been infected with influenza. They hope this can help them create more effective influenza vaccines.
Objective:
- To learn about long-term changes in the body s immune system after influenza infection.
Eligibility:
- People who have completed a previous LID Clinical Studies Unit influenza challenge study or current or prior participation in an LID natural history study and are willing to have samples stored for future research.
Design:
- Eligible participants will be asked to visit the clinic every 3 months for 2 years.
- During each visit, participants will have blood drawn from an arm vein using a needle and a syringe and a nasal sample.
- Participants will have a medical history and physical exam and vital signs performed. This will include blood pressure, heart rate, breathing rate, temperature, weight, and finger-measured blood oxygen. They will answer questions about any medicines taken and possible recent illnesses.
- If participants have symptoms of influenza, they may have an additional sample taken from the nose.
- Participants will complete a health questionnaire once a month on a secure website. Participants may also give their responses over the telephone....
Detailed description
Circulating anti-influenza antibodies are an important factor in predicting clinical illness and severity in those infected with influenza. Specific antibodies against influenza include proteins targeting hemagglutinin (HA) and neuraminidase (NA). Lifelong immunity does not occur with influenza, either from natural infection or from vaccination. Due to the antigenic variation of Influenza A, individuals may become infected multiple times with the same subtype of influenza and even with the same strain. In the setting of natural infection and vaccination, antibody titer levels can persist initially, but then wane over time.
In our previous challenge studies, measurements of antibody responses have been focused solely on the acute infection period up to 2 months after initial infection. Long-term changes in immunity have not been investigated. The challenge setting gives us the unique ability to follow individuals from a specific, known and well-characterized exposure/illness to measure long-term changes in antibody titers from a pre-exposure baseline. This study could offer unique insight into how anti-influenza antibody titers change over time naturally and in response to other infections and life events. This type of controlled study has never been done and we believe monitoring titers long-term will help us better understand protective correlates of influenza.
In this natural history study, we will follow individuals who have undergone influenza challenge or have been naturally infected with influenza to evaluate changes in anti-influenza antibody titers over a 2-year period. Subjects will be followed for symptoms of influenza-like illness (ILI) and other changes in clinical status through quarterly clinical evaluations with blood draws. Monthly questionnaires will be used to follow subjects in between visits.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| 1 | – | –Post influenza infection |
Who may qualify
- Ages
- 18 to 120 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Healthy volunteers after influenza challenge and patients after natural influenza infection
Key inclusion criteria (5 listed)
- Participants may be co-enrolled in other research studies. This will be addressed on a case-by-case basis with the approval of the principal investigator (PI) or associate investigator.
- If a participant enrolls in another influenza challenge study, the participant will be removed from this study. The participant can re-enroll in this study after completion of the influenza challenge study and will be followed for two years following completion of the most recent influenza challenge study.
Key exclusion criteria (1 listed)
- Any condition or event that, in the PI s opinion, may substantially increase the risk associated with study participation or compromise the study s scientific objectives. Conditions that exclude a subject are considered to be unlikely, but an example would include a newly diagnosed medical condition that may alter a participant s immune system and make it unsafe to obtain scheduled blood samples for research purposes.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
To characterize the timing of peak antibody response to hemagglutinin (HA) and neuraminidase (NA) post influenza challenge or after natural infection To evaluate the long-term variability of hemagglutinin inhibition (HAI) and neuraminidase inhib...
Time frame: 2 years
Trend of HAI titer over multiple time points Trend of NAI titer over multiple time points
1 secondary outcome
To correlate changes in clinical status such as influenza-like illness (ILI) or vaccinations with changes in antibody titers and other immune measures
Time frame: 2 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 Oct 2026.
- Background: PubMed 25121712Grohskopf LA, Olsen SJ, Sokolow LZ, Bresee JS, Cox NJ, Broder KR, Karron RA, Walter EB; Centers for Disease Control and Prevention. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP) -- United States, 2014-15 influenza season. MMWR Morb Mortal Wkly Rep. 2014 Aug 15;63(32):691-7.
- Background: PubMed 19453440Thompson WW, Weintraub E, Dhankhar P, Cheng PY, Brammer L, Meltzer MI, Bresee JS, Shay DK. Estimates of US influenza-associated deaths made using four different methods. Influenza Other Respir Viruses. 2009 Jan;3(1):37-49. doi: 10.1111/j.1750-2659.2009.00073.x.
- Background: PubMed 23291930Cox RJ. Correlates of protection to influenza virus, where do we go from here? Hum Vaccin Immunother. 2013 Feb;9(2):405-8. doi: 10.4161/hv.22908. Epub 2013 Jan 4.
- NIH Clinical Center Detailed Web PageLink provided by the sponsor.
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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.
Alison Han, M.D. principal investigator
National Institute of Allergy and Infectious Diseases (NIAID)
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 Post Influenza, run by National Institute of Allergy and Infectious Diseases (NIAID) at 1 site in United States.
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 5 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: enrolling by invitation, as of the sponsor's last update on 29 Oct 2026. 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 United States. 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?
This study is still under way. Results are not available in the source record yet.
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?
To characterize the timing of peak antibody response to hemagglutinin (HA) and neuraminidase (NA) post influenza challenge or after natural infection To evaluate the long-term variability of hemagglutinin inhibition (HAI) and neuraminidase inhib... (time frame: 2 years). 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 NCT02511002, which also lists 3 linked publications.
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 29 Oct 2026.