Safety and Immunogenicity of RSVpreF Coadministered With SIIV in Adults ≥65 Years of Age

Local reactions were collected at the RSVpreF or placebo injection site after Vaccination 1 and Vaccination 2 and were recorded by participants using electronic diary (e-diary). Local reactions included redness, swelling and pain at injection site. Redness and swelling were measured and recorded in measuring device units where, 1 measuring device unit =0.5 centimeter (cm) and were graded as mild (greater than [>] 2.0 to 5.0 cm), moderate (>5.0 to 10.0 cm), and severe (>10.0 cm). Pain at injection site was graded as mild (did not interfere with activity), moderate (interfered with activity), and severe (prevented daily activity). Percentage of participants reporting local reactions at injection site in Coadministration Group, and Sequential-Administration Group and associated 2-sided 95% confidence interval (CI) based on Clopper and Pearson method was presented in this outcome measure (OM). Safety population=all enrolled participants who received study intervention (RSVpreF, placebo).

Systemic events included fever, fatigue, headache, nausea, vomiting, diarrhea, muscle pain and joint pain and were recorded by participants using an e-diary. Fever was defined as an oral temperature >=38.0 degree Celsius (deg C) and categorized as >=38.0 to 38.4 deg C (mild), >38.4 to 38.9 deg C (moderate), >38.9 to 40.0 deg C (severe) and >40.0 deg C (grade 4). Fatigue, headache, nausea, muscle pain and joint pain were graded as mild (did not interfere with activity), moderate (some interference with activity) and severe (prevented daily routine activity). Vomiting was graded mild: 1 to 2 times in 24 hours (h), moderate: >2 times in 24h, and severe: required intravenous hydration. Diarrhea was graded mild: 2 to 3 loose stools in 24h, moderate: 4 to 5 loose stools in 24h and severe: 6 or more loose stools in 24h. Percentage of participants with systemic events within 7 days after each vaccination and the associated 2-sided 95% CI based on the Clopper and Pearson method was presented.

An AE was defined as any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Percentage of participants reporting AEs within 1 month after Vaccination 1 were reported in this outcome measure. Exact 2-sided CI was calculated using 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.

An AE was defined as any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. Percentage of participants reporting AEs within 1 month after Vaccination 2 were reported in this outcome measure. Exact 2-sided CI was calculated using 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.

An SAE was defined as an AE that, at any dose: resulted in death; was life-threatening; required inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent disability/incapacity; was a congenital anomaly/birth defect; was a suspected transmission via a Pfizer product of an infectious agent, pathogenic or nonpathogenic or that was considered to be an important medical event. Percentage of participants with SAEs and the associated 2-sided 95% CI based on the Clopper and Pearson method was presented. Percentage of participants reporting SAEs within 1 month after Vaccination 1 were reported in this outcome measure.

An SAE was defined as an AE that, at any dose: resulted in death; was life-threatening; required inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent disability/incapacity; was a congenital anomaly/birth defect; was a suspected transmission via a Pfizer product of an infectious agent, pathogenic or nonpathogenic or that was considered to be an important medical event. Percentage of participants with SAEs and the associated 2-sided 95% CI based on the Clopper and Pearson method was presented. Percentage of participants reporting SAEs within 1 month after Vaccination 2 were reported in this outcome measure.

Geometric mean titer (GMT) of RSV A and RSV B neutralizing titers for the Coadministration Group and Sequential-Administration Group were reported in this outcome measure in descriptive data section. GMTs and the 2-sided 95% CI were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on Student's t distribution). Assay results below the lower limit of quantification (LLOQ) were set to 0.5*LLOQ. Geometric mean ratio (GMR) was reported in the statistical analysis section and was calculated as ratio of GMTs in the Coadministration Group to the Sequential-Administration Group.

GMTs of strain-specific HAI titers for the Coadministration Group and Sequential-Administration Group were reported in this outcome measure in descriptive data section. GMTs and the 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on Student's t distribution). Assay results below the LLOQ were set to 0.5*LLOQ. GMR was reported in the statistical analysis section and was calculated as ratio of GMT in the Coadministration Group to the Sequential-Administration Group.

GMT of neutralizing titers of RSV A and RSV B before vaccination, at 1 month and 2 months after vaccination was reported in this outcome measure. Assay results below the LLOQ were set to 0.5*LLOQ. GMTs and the corresponding 2-sided CIs were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on Student's t distribution). For Sequential-Administration Group, the time point for 2 months after vaccination was not reported since the participants received RSVpreF at Vaccination 2 and were followed up for 1 month after Vaccination 2.

GMFR of neutralizing titers of RSV A and RSV B before vaccination and at 1 month and 2 months after vaccination was reported in this outcome measure. GMFR and the corresponding 2-sided CIs were calculated by exponentiating the mean logarithm of the fold rises from before vaccination and the corresponding CIs (based on the Student's t distribution).

HAI GMT before vaccination and 1 month after vaccination with SIIV was reported in this outcome measure. GMTs and the corresponding 2-sided CIs were calculated by exponentiating the mean logarithm of the titers and the corresponding CIs (based on Student's t distribution).

GMFR of strain-specific HAI titers before vaccination and 1 month after vaccination with SIIV was reported in this outcome measure. GMFRs and the corresponding 2-sided CIs were calculated by exponentiating the mean logarithm of fold rises (later time point over earlier time point) and the corresponding CIs (based on Student's t distribution).