A Study to Learn About ABRYSVO Vaccine in Older Adults to Prevent Severe Respiratory Syncytial Virus (RSV) Disease

RETROSPECTIVE STUDY EVALUATING ABRYSVO® VACCINE EFFECTIVENESS AGAINST SEVERE LOWER RESPIRATORY TRACT DISEASE IN OLDER ADULTS

The main purpose of this study is to learn about the effectiveness of Pfizer's ABRYSVO vaccine. This vaccine helps to prevent infections caused by Respiratory Syncytial Virus (RSV). RSV is a virus that can cause infections in the airways. These symptoms can be cold-like symptoms, but in some cases can lead to severe symptoms or hospitalization.

This study uses only healthcare data that are already collected from routine visits to healthcare providers. This means that participants will not be actively enrolled in the study and there are no study treatments. The study will look at data for about two years. This study will look at patient information from:

• Adults ages 60 years and older
• Adults who are eligible to receive the ABRYSVO vaccination

Substudy A:

• This study will assess the duration of protection of ABRYSVO in adults ages 60 years and older after completion of the original study.
• The substudy will look at data from subsequent RSV seasons after the first dose of ABRYSVO for about 5 years.

Substudy B:

• This study will assess vaccine effectiveness of ABRYSVO after revaccination in routine use, pending ACIP recommendation for revaccination.
• The substudy will look at data for about 2 years after revaccination.

The overall research question asks how effective ABRYSVO® is against severe RSV disease in real-world populations. The primary objective of this study is to estimate the VE of Pfizer's ABRYSVO® vaccine against RSV-related LRTD hospitalizations among Kaiser Permanente Southern California members who are eligible for vaccination per Advisory Committee on Immunization Practices (ACIP) recommendations. Key secondary objectives include determining ABRYSVO® VE against RSV-related LRTD hospitalizations among the immunocompetent and stratified by age group (60-74 years vs 75 years and older). Additional secondary objectives include assessment of ABRYSVO® VE stratified by RSV subgroup, against ARI endpoints, death, among high-risk subgroups, and against critical outcomes.

A case control study with test negative design will be the primary analysis assessing RSV-related outcomes. An exploratory cohort design may also be used to assess all-cause outcomes and RSV-related outcomes.

Standard-of-care specimens (e.g. stored remnant respiratory specimens) from patients who did not receive RSV testing, who tested negative for RSV via RSV-only test, or a had limited multiplex viral respiratory panel assay will be salvaged and tested using a full respiratory multiplex polymerase chain reaction (PCR) panel at KPSC. Further, all RSV positives will be tested for RSV A and RSV B.

Inclusion Criteria:

1. KPSC patients eligible to receive ABRYSVO® per ACIP recommendations for adults ages 60 and older who are admitted to the hospital with ARI/LRTD, (defined using International Classification of Diseases (ICD) codes after start of study period, and who have had an RSV test, either through SOC testing or blinded study testing of remnant respiratory specimens.
2. For secondary objectives estimating VE against ED admission, the TND will include KPSC patients eligible to receive ABRYSVO® who present to the ED with ARI/LRTD after start of study period, and who have had an RSV test, either through standard of care testing or blinded study testing of remnant respiratory specimens.
3. For exploratory objectives estimating VE against RSV-related cardiac hospitalization, the TND will include KPSC patients eligible to receive ABRYSVO® who are hospitalized or present to the ED with cardiac events (defined using ICD codes) after start of study period, and who have had an RSV test, either through SOC testing or blinded study testing of remnant respiratory specimens.
4. We will include membership requirement of 1 year prior to index date, which is defined as the date of hospitalization or ED admission (allowing 45-day administrative gap), to facilitate accurate capture of comorbid conditions.

Exclusion Criteria:

Patients meeting any of the following criteria will not be included in the study:

We will exclude patients who receive another licensed or investigational RSV vaccine prior to hospitalization or ED visit from the study population and analysis. Patients will be excluded if the index date is within certain time windows from vaccination date, outlined further in the exposure section below.

SSA and SSB Eligibility Criteria:

The inclusion criteria for Substudy A are described above for the Test Negative Design.