Evaluating influenza, SARS-CoV-2, and other respiratory virus vaccine effectiveness in prevention of acute illness in Washington state 2022-2027

ABSTRACT As one of the current US Influenza Vaccine Effectiveness (US Flu VE) Network sites, we propose continuing our studies of vaccine effectiveness (VE) for seasonal influenza, COVID-19, and other respiratory viruses to prevent acute respiratory illness (ARI) in Washington state from 2022 to 2027 (Component A). Since March 2020, the COVID-19 pandemic has resulted in >80 million infections and ~1 million US deaths. Until the pandemic, the dominant respiratory virus impacting public health seasonally was influenza. In the US, up to 5% of the population sought outpatient care during a severe epidemic, and a typical epidemic caused tens of thousands of deaths and hundreds of thousands of hospitalizations. The COVID-19 pandemic catalyzed rapid adoption of telehealth care, in particular for patients with mild to moderate ARI, shifting patients from ambulatory visits to minimize healthcare exposure to COVID-19. Currently, influenza and COVID-19 vaccinations are the best available tools for reducing the respiratory virus burden and maintaining population immunity. Vaccination programs represent a substantial public health investment. Given the magnitude of this investment and the dynamic impact of respiratory viruses on public health, policymakers need accurate, timely, and relevant data representing real-world VE to monitor the impact on respiratory illness burden in US populations. The next 5 years of surveillance of respiratory illness in US populations will be critical in accounting for changes in respiratory virus burden. The US Flu VE Network has the capacity, infrastructure, research methods, and specimen collection experience to monitor any respiratory virus within US health care. From 2022-2027, we propose to enroll ~6000 KPWA infants, children, and adults including older adults in urgent care clinics, collect respiratory and blood specimens, complete enrollment and post-enrollment questionnaires, collaborate with laboratory services to type and genetically sequence specimens, collate and curate EHR data, collaborate across the Network with Component A sites, share data with Network Coordination Center (Component B), share specimens with site leading Component E, participate in Network research activities including dissemination, and develop new methods for estimation and inference in VE. Our specific aims to meet the goals of the US Flu VE Network are: Aim 1. Establish a platform to estimate VE of seasonal influenza and COVID-19 vaccines against respiratory viral illnesses in preventing laboratory- confirmed illness among children and adults with mild or moderate illness seeking care in ambulatory settings (Objective 1); Aim 2. Establish a protocol to obtain influenza and SARS-CoV-2 viral sequences from specimens collected among infected participants in the proposed outpatient network (Objective 2); Aim 3. Describe capacity and diagnostic test methods available in KPWA and methods to obtain COVID-19 vaccination data outside influenza season (Objective 3). Aim 4. Improve precision of the test-negative design by incorporate two-phase sampling methodology (methods aim).