Use and Effectiveness of COVID-19 Vaccines Using State Vaccine Registries and Insurance Claims Data

This study aims to use vaccination information from state vaccine registries linked with HealthVerity insurance claims for the following:

* to measure how effective the Pfizer-BioNTech vaccine is at preventing post-COVID conditions.
* to understand characteristics of patients who are receiving COVID-19 vaccines.

All patients whose information is kept unidentified in the HealthVerity database are eligible to be included for both aims of this study.

The effectiveness of the COVID-19 vaccine in preventing post-COVID health conditions will be assessed (Aim 1). To do this, a retrospective cohort time-to-event design will be employed. Patients will be observed until an endpoint (post-COVID related condition) or a censoring event (BNT162b2 vaccine, Other COVID-19 vaccinations formulated for 2023-2024 respiratory season, moderate/severe immunocompromised condition, or pregnancy). All eligible patients are considered unvaccinated (unexposed) at cohort entry. Patients then continue to contribute person-time to the time-to-event model as the study progresses. Patient data will be gathered from HealthVerity, including those enrolled in the claims database, and supplemented with information from the state's deidentified vaccine registry. Only patients eligible to receive the vaccine during the study period will be included in the analysis of post-COVID health conditions.

The second part of the study (Aim 2) will use a retrospective cohort design to examine the uptake of the vaccine in specific groups over time. Subjects will be identified through three different methods: 1) by analyzing all available dosing records in the Immunization Registry, 2) by using HealthVerity claims data based on specific calendar time periods when the vaccine was available, or 3) based on the start of pregnancy that occurs after EUA date. Patients will be followed until experiencing the vaccination under study, disenrollment, end of data or death. Vaccinations will be assessed overall and also by specific type of prior dose (mRNA vs other).

Eligibility Criteria:
Aim 1:

Inclusion Criteria:

Patients must meet all of the following criteria to be eligible for inclusion in the study:

1. Patients in HealthVerity database and residing in California or Louisiana as of 25 September 2023 AND
2. Have ≥1 year of pharmacy and medical enrollment in HealthVerity prior to cohort entry date, allowing for up to a 30-day gap in enrollment AND
3. ≥18 years old as of 11 September 2023 AND
4. Have resided only in their respective state (California or Louisiana) for ≥1 year prior to 11 September 2023

Exclusion Criteria:

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

1. Patients who were pregnant (using any pregnancy code) or immunocompromised from 1 year prior to cohort entry
2. Patients who received any 2023-2024 XBB-adapted formulation of the COVID-19 vaccine prior to authorization (11 September 2023)
3. Patients who have discrepancies in sex and/or year of birth between HealthVerity claims and state immunization registry datasets
4. Patients who had a prior diagnosis of COVID-19 ≤180 days preceding cohort entry

Aim 2:

By Age, Bivalent (older children, adults)

Patients must meet all of the following inclusion criteria to be eligible for inclusion in the study:

1. Has medical and pharmacy enrollment in HealthVerity as of August 31, 2022
2. And is age ≥12 years
3. With 6 months of continuous medical and pharmacy enrollment before calendar index date
4. And does not have evidence of moderate/severe immunocompromise as defined by CDC
5. And has evidence of ≥2 doses of COVID-19 original vaccine formulation before the calendar index date
6. And does not have original vaccine formulation within 2 months before calendar index date
7. And does not have a pregnancy start date within 9 months before or any point after calendar entry
8. And does not have discrepancies in sex and/or year of birth between HealthVerity claims and state Immunization registry datasets.

This analysis will be stratified by age: 12-17, 18-49. 50-64, 65-74, 75+, which will be measured as of August 31, 2022.

By Age, Bivalent (younger children)

Patients must meet all of the following inclusion criteria to be eligible for inclusion in the study:

1. Has medical and pharmacy enrollment in HealthVerity as of 12 October 2022
2. And is age 5-11 years
3. With 6 months of continuous medical and pharmacy enrollment before calendar index date
4. And does not have evidence of moderate/severe immunocompromise as defined by CDC
5. And has evidence of ≥2 doses of COVID-19 original vaccine formulation before the calendar index date
6. And does not have original vaccine formulation within 2 months before calendar index date.

By Age, Bivalent (youngest children)

Patients must meet all of the following inclusion criteria to be eligible for inclusion in the study:

1. Has medical and pharmacy enrollment in HealthVerity as of 08 December 2022
2. And is age 6 months-4 years
3. With 6 months of continuous medical and pharmacy enrollment before calendar index date
4. And does not have evidence of moderate/severe immunocompromise as defined by CDC
5. And has evidence of ≥2 doses of COVID-19 original vaccine formulation before the calendar index date
6. And does not have original vaccine formulation within 2 months before calendar index date.

By Disease Status, Bivalent

Patients must meet all of the following inclusion criteria to be eligible for inclusion in the study:

1. Has medical and pharmacy enrollment in HealthVerity as of 31 August 2022
2. And is age \>=6 months
3. And has continuous medical and pharmacy enrollment for 6 months before the calendar index date
4. And has evidence of 1) moderate/severe immunocompromising condition or separately 2) COVID high-risk condition in a period before the calendar index period (lookback times are dependent on the disease and are provided in variable table below)
5. And has evidence of ≥3 doses of COVID-19 original vaccine formulation before the calendar index date.

For Pregnant Women, Bivalent

Patients must meet all of the following inclusion criteria to be eligible for inclusion in the study:

1. Has at least 6 months of medical and pharmacy enrollment in HealthVerity as of 31 August 2022
2. And is female sex
3. Aged 12-49
4. And has estimated date of pregnancy start date within 9 months before or any point after the calendar entry date (determined using gestational age algorithm)
5. And has evidence of ≥2 doses of COVID-19 original vaccine formulation before the pregnancy start date or 31 August 2022, whichever is latest.
6. And did not receive the bivalent dose prior to pregnancy, if estimated pregnancy start date is after 31 August 2022