A Phase 3 interventional study of RSVpreF Vaccine and Placebo in Respiratory Syncytial Virus, sponsored by Pfizer. Completed at 16 sites in South Korea. Open to participants aged 60 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-02-09.
Sponsored by Pfizer · Phase 3, Interventional, and Prevention
The goal of this clinical trial is to quantify the immune response in older Korean adults after a RSVpreF vaccination. It will also learn about the safety and tolerability of RSVpreF vaccination. The main questions it aims to answer are:
What local reactions and systemic events do participants have after a RSVpreF vaccination? What medical problems do participants have after a RSVpreF vaccination? Researchers will compare RSVpreF to a placebo (a look-alike substance that contains no RSVpreF) to see if RSVpreF is safe and well tolerated. It will also examine the change in antibody levels (immune responses) before and after vaccination.
Participants will:
Receive the RSVpreF vaccination or a placebo injection once at Visit 1. Visit the clinic a month later for a checkup and tests. Receive a phone call 1 week after vaccination, and 2 months after vaccination, for health checks.
Keep a diary of their symptoms for 7 days after vaccination.
This is a Phase 3, randomized, double-blinded, placebo-controlled, multicenter trial to describe the safety, tolerability, and immunogenicity of bivalent RSVpreF in adults 60 years of age and older in Korea.
The study duration is approximately 2 months. 4 study visits are required and are comprised of 2 scheduled clinic visits and 2 scheduled telephone calls.
Approximately 360 study-eligible participants will be randomized to receive either the 120-µg dose of RSVpreF or placebo in a 2:1 ratio.
After screening and confirmation of eligibility, a prevaccination blood sample will be collected for immunogenicity assessments and a single dose of study intervention (RSVpreF or placebo) will be administered.
Participants will report daily reactogenicity data using an electronic device for 7-days or until resolution.
Participants will return approximately 1 month later for a follow-up blood draw for immunogenicity assessments and collection of safety information.
A telephone follow-up visit will be conducted approximately 1 week after vaccination to review reactogenicity and approximately 2 months after vaccination to collect safety information.
For all participants, adverse events (AEs) will be collected from informed consent through 1 month following study intervention administration. Serious adverse events (SAEs) newly diagnosed chronic medical conditions (NDCMCs), and adverse events of special interest (AESIs) will be collected from informed consent throughout study participation.
1,031 studies on the registry are indexed under Respiratory Tract Infections; 144 are open to participants now.
This study's enrollment of 378 is above the median of 199 across 698 interventional studies indexed under Respiratory Tract Infections.
Browse Respiratory Tract Infections studies →Pfizer is the lead sponsor of 3,244 studies on the registry; 139 are open to participants now.
Of its 582 completed or terminated interventional studies of FDA-regulated products, 381 (65%) have results posted.
Counted across the registry records on this site, refreshed daily.
Participants 60 years of age or older at Visit 1
Healthy participants who are determined by medical history, physical examination (if required), and clinical judgment of the investigator to be eligible for inclusion in the study.
Healthy participants with preexisting stable disease, defined as disease not requiring significant change in therapy or hospitalization for worsening disease during the 6 weeks before enrollment, can be included.
Exclusion Criteria:
Individuals who receive chronic systemic treatment with immunosuppressive therapy (other than systemic corticosteroids meeting the criteria noted below), including cytotoxic agents, immunosuppressive monoclonal antibodies, or radiotherapy, eg, for cancer or an autoimmune disease, from 60 days before study intervention administration or planned receipt throughout the study.
Receipt of systemic corticosteroids (≥20 mg/day of prednisone or equivalent) for
≥14 days from 28 days before study intervention.
Investigator site staff directly involved in the conduct of the study and their family members, site staff otherwise supervised by the investigator, and sponsor and sponsor delegate employees directly involved in the conduct of the study and their family members.
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Biological: RSVpreF Vaccine
Other: Placebo
RSV Vaccine 120 mcg
Placebo
Percentage of Participants With Local Reactions Within 7 Days After Vaccination
Local reactions included redness, swelling and pain at injection site. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit=0.5 centimeter (cm). Redness and swelling were graded as mild: \> 2.0 cm to 5.0 cm, moderate: \> 5.0 cm to 10.0 cm, severe: \>10.0 cm. Pain at injection site was graded as mild: did not interfere with activity, moderate: interfered with activity, severe: prevented daily activity. Any local reaction: any redness, any swelling, or pain at the injection site of at least mild severity. Exact 2-sided 95% confidence interval (CI) was based on the Clopper and Pearson method.
Time frame: From Day 1 to Day 7 after vaccination
Percentage of Participants With Systemic Events Within 7 Days After Vaccination
Systemic events included fever, fatigue, headache, vomiting, nausea, diarrhea, muscle pain and joint pain. Fever defined as oral temperature \>=38.0 degrees Celsius (deg C) and categorized as mild: \>=38.0 to 38.4 deg C, moderate: \>38.4 to 38.9 deg C, severe: \>38.9 to 40.0 deg C, and Grade 4: \>40.0 deg C. Vomiting categorized as mild: 1-2 times in 24 hours (h); moderate: \>2 times in 24h; severe: required intravenous (IV) hydration. Diarrhea categorized as mild: 2-3 loose stools in 24h; moderate: 4-5 loose stools in 24h; severe: 6 or more loose stools in 24h. Headache, fatigue, nausea, muscle pain and joint pain were categorized as mild: didn't interfere with activity; moderate: some interference with activity; severe: prevented daily routine activity. Exact 2-sided 95% CI was based on the Clopper and Pearson method.
Time frame: From Day 1 to Day 7 after vaccination
Percentage of Participants With Adverse Events (AEs) From Vaccination Through 1 Month After Vaccination
An AE was any untoward medical occurrence in a participant temporally associated with the use of study intervention, whether or not considered related to the study intervention. Exact 2-sided 95% CI was based on the Clopper and Pearson method. Only AEs collected by non-systematic assessment (i.e. excluding local reactions and systemic events) were reported in this outcome measure.
Time frame: From vaccination on Day 1 up to 1 month after vaccination
Percentage of Participants With Serious Adverse Events (SAEs) From Vaccination Throughout the Study
An SAE was defined as an AE that, at any dose met one of the following criteria: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity; was a congenital anomaly/birth defect; was a suspected transmission via a Pfizer product of an infectious agent, pathogenic or nonpathogenic; other significant medical events as judged by investigator. Exact 2-sided 95% CI was based on the Clopper and Pearson method.
Time frame: From vaccination on Day 1 up to 2 months after vaccination
Percentage of Participants With Newly Diagnosed Chronic Medical Conditions (NDCMCs) From Vaccination Throughout the Study
A NDCMC was defined as a disease or medical condition that was not identified prior to study start and was expected to be persistent or otherwise long-lasting in its effects. Newly diagnosed chronic medical condition did not include illnesses considered to be temporary conditions. Exact 2-sided 95% CI was based on the Clopper and Pearson method.
Time frame: From vaccination on Day 1 up to 2 months after vaccination
Geometric Mean Titer (GMT) of Neutralizing Titers (NTs) for RSV A and RSV B Before Vaccination
GMTs and the corresponding 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on the Student t distribution). Assay results below the lower limit of quantification (LLOQ) were set to 0.5\*LLOQ for analysis.
Time frame: Before Vaccination
Geometric Mean Titer (GMT) of Neutralizing Titers (NTs) for RSV A and RSV B at 1 Month After Vaccination
GMTs and the corresponding 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on the Student t distribution). Assay results below the LLOQ were set to 0.5\*LLOQ for analysis.
Time frame: 1 month after vaccination
Geometric Mean Fold Rise (GMFR) of Neutralizing Titers (NTs) for RSV A and RSV B From Before Vaccination to 1 Month After Vaccination
Fold rises was defined as ratios of the results after vaccination to the results before vaccination. GMFRs and 2-sided 95% CIs were calculated by exponentiating the mean logarithm of fold rises and the corresponding CIs (based on the Student t distribution).
Time frame: From before vaccination to 1 month after vaccination
Seroresponse Rates of Neutralizing Titers (NTs) for RSV A and RSV B at 1 Month After Vaccination
Seroresponse rate was defined as the percentage of participants with a postvaccination NT \>=4 times the LLOQ if the baseline titer (before vaccination) was below the LLOQ; or a \>=4-fold rise from baseline if the baseline titer was\>=LLOQ. 95% CI was based on Clopper-Pearson method.
Time frame: 1 month after vaccination
This study was conducted at 16 sites in the Republic of Korea.
| Milestone | RSVpreF 120 mcg | Placebo |
|---|---|---|
| Started | 252 | 126 |
| Vaccinated | 251 | 126 |
| Completed | 250 | 126 |
| Not completed | 2 | 0 |
| Withdrew: Protocol violation | 1 | 0 |
| Withdrew: Randomized, not vaccinated | 1 | 0 |
Local reactions included redness, swelling and pain at injection site. Redness and swelling were measured and recorded in measuring device units. 1 measuring device unit=0.5 centimeter (cm). Redness and swelling were graded as mild: \> 2.0 cm to 5.0 cm, moderate: \> 5.0 cm to 10.0 cm, severe: \>10.0 cm. Pain at injection site was graded as mild: did not interfere with activity, moderate: interfered with activity, severe: prevented daily activity. Any local reaction: any redness, any swelling, or pain at the injection site of at least mild severity. Exact 2-sided 95% confidence interval (CI) was based on the Clopper and Pearson method.
| Percentage of participants | RSVpreF 120 mcg | Placebo |
|---|---|---|
| Pain at injection site: any | 12.4 (8.5 to 17.1) | 3.2 (0.9 to 7.9) |
| Pain at injection site: mild | 11.6 (7.9 to 16.2) | 2.4 (0.5 to 6.8) |
| Pain at injection site: moderate | 0.8 (0.1 to 2.8) | 0.8 (0.0 to 4.3) |
| Pain at injection site: severe | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Redness: any | 2.8 (1.1 to 5.7) | 0.8 (0.0 to 4.3) |
| Redness: mild | 1.6 (0.4 to 4.0) | 0.8 (0.0 to 4.3) |
| Redness: moderate | 0.8 (0.1 to 2.8) | 0 (0.0 to 2.9) |
| Redness: severe | 0.4 (0.0 to 2.2) | 0 (0.0 to 2.9) |
| Swelling: any | 1.6 (0.4 to 4.0) | 0.8 (0.0 to 4.3) |
| Swelling: mild | 1.2 (0.2 to 3.5) | 0.8 (0.0 to 4.3) |
| Swelling: moderate | 0.4 (0.0 to 2.2) | 0 (0.0 to 2.9) |
| Swelling: severe | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Any local reaction: any | 14.7 (10.6 to 19.7) | 3.2 (0.9 to 7.9) |
| Any local reaction: mild | 12.4 (8.5 to 17.1) | 2.4 (0.5 to 6.8) |
| Any local reaction: moderate | 2.0 (0.6 to 4.6) | 0.8 (0.0 to 4.3) |
| Any local reaction: severe | 0.4 (0.0 to 2.2) | 0 (0.0 to 2.9) |
Systemic events included fever, fatigue, headache, vomiting, nausea, diarrhea, muscle pain and joint pain. Fever defined as oral temperature \>=38.0 degrees Celsius (deg C) and categorized as mild: \>=38.0 to 38.4 deg C, moderate: \>38.4 to 38.9 deg C, severe: \>38.9 to 40.0 deg C, and Grade 4: \>40.0 deg C. Vomiting categorized as mild: 1-2 times in 24 hours (h); moderate: \>2 times in 24h; severe: required intravenous (IV) hydration. Diarrhea categorized as mild: 2-3 loose stools in 24h; moderate: 4-5 loose stools in 24h; severe: 6 or more loose stools in 24h. Headache, fatigue, nausea, muscle pain and joint pain were categorized as mild: didn't interfere with activity; moderate: some interference with activity; severe: prevented daily routine activity. Exact 2-sided 95% CI was based on the Clopper and Pearson method.
| Percentage of participants | RSVpreF 120 mcg | Placebo |
|---|---|---|
| Fever: >=38.0°C | 0.4 (0.0 to 2.2) | 1.6 (0.2 to 5.6) |
| Fever: >=38.0°C to 38.4°C | 0 (0.0 to 1.5) | 1.6 (0.2 to 5.6) |
| Fever: >38.4°C to 38.9°C | 0.4 (0.0 to 2.2) | 0 (0.0 to 2.9) |
| Fever: >38.9°C to 40.0°C | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Fever: >40.0°C | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Fatigue: any | 23.1 (18.0 to 28.8) | 26.2 (18.8 to 34.8) |
| Fatigue: mild | 17.9 (13.4 to 23.2) | 15.9 (10.0 to 23.4) |
| Fatigue: moderate | 5.2 (2.8 to 8.7) | 10.3 (5.6 to 17.0) |
| Fatigue: severe | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Headache: any | 12.7 (8.9 to 17.5) | 11.1 (6.2 to 17.9) |
| Headache: mild | 11.6 (7.9 to 16.2) | 8.7 (4.4 to 15.1) |
| Headache: moderate | 1.2 (0.2 to 3.5) | 2.4 (0.5 to 6.8) |
| Headache: severe | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Muscle pain: any | 15.5 (11.3 to 20.6) | 9.5 (5.0 to 16.0) |
| Muscle pain: mild | 12.0 (8.2 to 16.6) | 5.6 (2.3 to 11.1) |
| Muscle pain: moderate | 3.6 (1.7 to 6.7) | 4.0 (1.3 to 9.0) |
| Muscle pain: severe | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Joint pain: any | 9.2 (5.9 to 13.4) | 7.9 (3.9 to 14.1) |
| Joint pain: mild | 6.0 (3.4 to 9.7) | 4.0 (1.3 to 9.0) |
| Joint pain: moderate | 3.2 (1.4 to 6.2) | 4.0 (1.3 to 9.0) |
| Joint pain: severe | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Nausea: any | 3.6 (1.7 to 6.7) | 6.3 (2.8 to 12.1) |
| Nausea: mild | 3.6 (1.7 to 6.7) | 4.0 (1.3 to 9.0) |
| Nausea: moderate | 0 (0.0 to 15) | 2.4 (0.5 to 6.8) |
| Nausea: severe | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Vomiting: any | 0 (0.0 to 1.5) | 0.8 (0.0 to 4.3) |
| Vomiting: mild | 0 (0.0 to 1.5) | 0.8 (0.0 to 4.3) |
| Vomiting: moderate | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Vomiting: severe | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Diarrhea: any | 4.8 (2.5 to 8.2) | 4.0 (1.3 to 9.0) |
| Diarrhea: mild | 4.8 (2.5 to 8.2) | 4.0 (1.3 to 9.0) |
| Diarrhea: moderate | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
| Diarrhea: severe | 0 (0.0 to 1.5) | 0 (0.0 to 2.9) |
An AE was any untoward medical occurrence in a participant temporally associated with the use of study intervention, whether or not considered related to the study intervention. Exact 2-sided 95% CI was based on the Clopper and Pearson method. Only AEs collected by non-systematic assessment (i.e. excluding local reactions and systemic events) were reported in this outcome measure.
| Percentage of participants | RSVpreF 120 mcg | Placebo |
|---|---|---|
| Percentage of Participants With Adverse Events (AEs) From Vaccination Through 1 Month After Vaccination | 3.6 (1.7 to 6.7) | 0.8 (0.0 to 4.3) |
An SAE was defined as an AE that, at any dose met one of the following criteria: resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity; was a congenital anomaly/birth defect; was a suspected transmission via a Pfizer product of an infectious agent, pathogenic or nonpathogenic; other significant medical events as judged by investigator. Exact 2-sided 95% CI was based on the Clopper and Pearson method.
| Percentage of participants | RSVpreF 120 mcg | Placebo |
|---|---|---|
| Percentage of Participants With Serious Adverse Events (SAEs) From Vaccination Throughout the Study | 0.8 (0.1 to 2.8) | 0.8 (0.0 to 4.3) |
A NDCMC was defined as a disease or medical condition that was not identified prior to study start and was expected to be persistent or otherwise long-lasting in its effects. Newly diagnosed chronic medical condition did not include illnesses considered to be temporary conditions. Exact 2-sided 95% CI was based on the Clopper and Pearson method.
| Percentage of participants | RSVpreF 120 mcg | Placebo |
|---|---|---|
| Percentage of Participants With Newly Diagnosed Chronic Medical Conditions (NDCMCs) From Vaccination Throughout the Study | 1.2 (0.2 to 3.5) | 0 (0.0 to 2.9) |
GMTs and the corresponding 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on the Student t distribution). Assay results below the lower limit of quantification (LLOQ) were set to 0.5\*LLOQ for analysis.
| Titer | RSVpreF 120 mcg | Placebo |
|---|---|---|
| RSV A | 1472 (1326 to 1636) | 1617 (1402 to 1866) |
| RSV B | 1957 (1766 to 2168) | 1865 (1601 to 2174) |
GMTs and the corresponding 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on the Student t distribution). Assay results below the LLOQ were set to 0.5\*LLOQ for analysis.
| Titer | RSVpreF 120 mcg | Placebo |
|---|---|---|
| RSV A | 14240 (12977 to 15625) | 1397 (1199 to 1628) |
| RSV B | 16277 (14623 to 18117) | 1813 (1554 to 2115) |
Fold rises was defined as ratios of the results after vaccination to the results before vaccination. GMFRs and 2-sided 95% CIs were calculated by exponentiating the mean logarithm of fold rises and the corresponding CIs (based on the Student t distribution).
| Fold rise | RSVpreF 120 mcg | Placebo |
|---|---|---|
| RSV A | 9.5 (8.51 to 10.67) | 0.9 (0.78 to 0.94) |
| RSV B | 8.3 (7.37 to 9.39) | 1.0 (0.89 to 1.06) |
Seroresponse rate was defined as the percentage of participants with a postvaccination NT \>=4 times the LLOQ if the baseline titer (before vaccination) was below the LLOQ; or a \>=4-fold rise from baseline if the baseline titer was\>=LLOQ. 95% CI was based on Clopper-Pearson method.
| Percentage of participants | RSVpreF 120 mcg | Placebo |
|---|---|---|
| RSV A | 81.0 (75.6 to 85.7) | 0.8 (0.0 to 4.4) |
| RSV B | 75.9 (70.1 to 81.1) | 0.8 (0.0 to 4.3) |
Collected over All-cause mortality and SAEs: From vaccination on Day 1 up to 2 months after vaccination. Other AEs (non-systematic assessment): From vaccination on Day 1 up to 1 month after vaccination; Local reactions and systemic events (systematic assessment): From Day 1 to Day 7 after vaccination. Non-serious events are listed at a 0% frequency threshold.
| Group | Deaths | Serious | Other |
|---|---|---|---|
| RSVpreF 120 mcg | 0/251 (0%) | 2/251 (0.8%) | 100/251 (39.8%) |
| Placebo | 0/126 (0%) | 1/126 (0.8%) | 43/126 (34.1%) |
| Event | RSVpreF 120 mcg | Placebo |
|---|---|---|
| Retinal detachmentEye disorders | 0/251 | 1/126 |
| EnteritisGastrointestinal disorders | 1/251 | 0/126 |
| AsthmaRespiratory, thoracic and mediastinal disorders | 1/251 | 0/126 |
| Event | RSVpreF 120 mcg | Placebo |
|---|---|---|
| Fatigue (FATIGUE)General disorders | 58/251 | 33/126 |
| Myalgia (MUSCLE PAIN)Musculoskeletal and connective tissue disorders | 39/251 | 12/126 |
| Headache (HEADACHE)Nervous system disorders | 32/251 | 14/126 |
| Injection site pain (PAIN AT INJECTION SITE)General disorders | 31/251 | 4/126 |
| Arthralgia (JOINT PAIN)Musculoskeletal and connective tissue disorders | 23/251 | 10/126 |
| Nausea (NAUSEA)Gastrointestinal disorders | 9/251 | 8/126 |
| Diarrhoea (DIARRHEA)Gastrointestinal disorders | 12/251 | 5/126 |
| Erythema (REDNESS)Skin and subcutaneous tissue disorders | 7/251 | 1/126 |
| Swelling (SWELLING)General disorders | 4/251 | 1/126 |
| Pyrexia (FEVER)General disorders | 1/251 | 2/126 |
Safety population included all screened participants who received the study intervention in the study.
| Age, Continuous(Years) | RSVpreF 120 mcg | Placebo | Total |
|---|---|---|---|
| Mean | 67.3 ± 5.18 | 67.3 ± 5.19 | 67.3 ± 5.17 |
| Sex: Female, Male(Participants) | RSVpreF 120 mcg | Placebo | Total |
|---|---|---|---|
| Female | 168 | 76 | 244 |
| Male | 83 | 50 | 133 |
| Race/Ethnicity, Customized(Participants) | RSVpreF 120 mcg | Placebo | Total |
|---|---|---|---|
| Race — Asian | 251 | 126 | 377 |
| Race/Ethnicity, Customized(Participants) | RSVpreF 120 mcg | Placebo | Total |
|---|---|---|---|
| Ethnicity — Non-Hispanic/non-Latino | 251 | 126 | 377 |
Documents are hosted by the registry — open the source record to download them.
Plan to share: Yes — 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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