# P-1809. Trends in vaccination and diagnostic testing for SARS-CoV-2 and influenza across the United States, 2019 – 2024

## TL;DR

This study examines how vaccination and testing for SARS-CoV-2 and influenza changed in the US from 2019 to 2024, showing a shift toward more vaccination use over testing.

## Contribution

The study provides new insights into the changing dynamics of vaccination and diagnostic testing integration in health systems during and after the pandemic.

## Key findings

- SARS-CoV-2 testing decreased significantly in 2024 compared to 2021, while influenza testing increased sharply.
- Vaccination use surpassed testing for SARS-CoV-2 in adults during the pandemic, but shifted post-pandemic.
- Breakthrough SARS-CoV-2 infections increased in adults aged 65+ after 180 days post-vaccination in late 2023 to early 2024.

## Abstract

To assess trends in SARS-CoV-2 and influenza virus testing and positivity rates in populations administered seasonal vaccines.Change in yearly testing volumes for SARS-CoV-2 and influenza in adult and pediatric populationsMonthly vaccination to testing volumes of SARS-CoV-2 and influenza in adult and pediatric populations

Change in yearly testing volumes for SARS-CoV-2 and influenza in adult and pediatric populations

Monthly vaccination to testing volumes of SARS-CoV-2 and influenza in adult and pediatric populations

We retrospectively reviewed 604,977 vaccination events and 881,573 tests for SARS-CoV-2 and 4,958,425 vaccination events and 31,274 tests for influenza from 2019 to 2024 in a US population administered seasonal vaccines with respiratory diagnostic testing performed at Labcorp. Monthly vaccination volume to testing volume ratio (mVTR) was used to estimate integration of vaccinations and diagnostic testing in health service systems.Breakthrough infection rates for SARS-CoV-2 and influenza by ageComparisons of breakthrough infection rates between <180 days and 181 – 365 days performed with two-sample proportion Z-tests. ***: p < 0.001, **: p < 0.01, *: p < 0.05, n.s.: not significant.

Breakthrough infection rates for SARS-CoV-2 and influenza by age

Comparisons of breakthrough infection rates between <180 days and 181 – 365 days performed with two-sample proportion Z-tests. ***: p < 0.001, **: p < 0.01, *: p < 0.05, n.s.: not significant.

SARS-CoV-2 testing decreased 94.8% in pediatrics and 96.5% in adults in 2024 compared to 2021. Influenza testing increased 367.5% in pediatrics and 766.8% in adults in 2024 compared to 2019 (Fig 1). SARS-CoV-2 testing was utilized more than vaccines in adults with mean mVTR = 0.8, SD = 1.0 and was used at similar levels to vaccines in pediatrics with mean mVTR = 1.0, SD = 0.8 during the COVID-19 pandemic (01/2021 – 05/2023) (Fig 2). More vaccines were utilized relative to testing in adults (2024 peak mVTR = 123.4) and pediatrics (2024 peak mVTR = 23.9) after the pandemic. Seasonal variations in SARS-CoV-2 mVTR resembling those of influenza were noted. There were higher volumes of influenza vaccines relative to influenza testing in both adults (2024 peak mVTR = 948.3) and pediatrics (2024 peak mVTR = 370.9).

Breakthrough SARS-CoV-2 infection rates at < 180 days and 181 – 365 days were not significantly different for most vaccination seasons (Fig 3). However, in adults aged 65+ who were vaccinated between 09/2023 – 02/2024 a significant increase in breakthrough infection rates at 181 – 365 days (21.3%) was seen compared to < 180 days (2.3%; p < 0.001). Breakthrough SARS-CoV-2 infection rates were mostly lower with vaccines received 09/2023 – 02/2024 compared to previous vaccination seasons. Breakthrough influenza infections occurred at higher rates within 180 days of vaccination especially in pediatrics.

Interventions for SARS-CoV-2 have recently shifted towards increased utilization of vaccination over diagnostic testing similar to seasonal patterns seen with influenza. Detection of breakthrough SARS-CoV-2 infection may have been impacted by decreased testing in recent months.

Min Kyung Lee, PhD, Labcorp: Employee|Labcorp: Stocks/Bonds (Public Company) David Alfego, PhD, Labcorp: Employee|Labcorp: Employee|Labcorp: Stocks/Bonds (Public Company) Laura Gillim, PhD, Labcorp: Stocks/Bonds (Public Company) Charles M. Walworth, MD, Labcorp: Employee|Labcorp: Stocks/Bonds (Public Company)|Labcorp: Stocks/Bonds (Public Company) Suzanne Dale, PhD, Labcorp: Stocks/Bonds (Public Company) Kathryn Lang, MD, PhD, VaxCare: Advisor/Consultant Ruth Carrico, PhD, DNP, APRN, VaxCare: Advisor/Consultant Colm Smart, MBA, VaXcare: Stocks/Bonds (Private Company) Payman Ghasemi, PhD, VaxCare: Grant/Research Support