At-home antibody tests can alert people if they need another COVID-19 vaccine

July 11, 2024

In a new study published online June 12, 2024, by the journal Science Advances, researchers examined whether simple at-home antibody tests could accurately let people know if they need another COVID-19 vaccine to boost their immunity.

This question is timely because, while more than 95% people in the United States had COVID-19 antibodies from either infection or vaccination by the end of 2022, immunity wanes over time — especially against new variants like Omicron.

Despite recommendations for booster shots that target new variants — and increased accessibility of these boosters — many people have not received their third or fourth doses due to concerns over side effects, questions about effectiveness against emerging strains, general vaccine hesitancy and a reduced sense of urgency.

Among U.S residents aged 65 and older, only about 40% got the bivalent booster. This is especially concerning as the 2024 COVID-19 death toll may approach 73,000, making it the eighth-leading cause of death in the U.S. for the year.

In an effort to validate a new tool that could assess immunity status and prompt people to “re-up” their COVID-19 vaccine, the research team checked the antibody levels of 237 health care workers. All the study participants previously had received mRNA COVID vaccines, and they took lateral flow antibody tests — similar to at-home pregnancy tests — to check their current level of protection.

Afterward, the researchers conducted more advanced lab tests and confirmed that people who tested negative on the at-home tests did indeed lack antibodies and, therefore, sufficient immune protection against COVID-19. (However, testing positive on the at-home test did not necessarily mean someone was fully protected.)

Dr. Ralph Baric

The study was co-led by Michael Mallory, MPH, and Jennifer Munt, BS, two researchers from the University of North Carolina at Chapel Hill’s Gillings School of Global Public Health’s Department of Epidemiology who also work in the UNC School of Medicine’s Department of Microbiology and Immunology. Other co-authors from Carolina include Lakshmanane Premkumar, PhD, Tara Narowski, BS, Izabella Castillo, BS, and Edwing Cuadra, MSc, from the Department of Epidemiology, and Ralph Baric, PhD, and John Powers, PhD, from the Departments of Epidemiology and Microbiology and Immunology.

“This study expands on previous findings from a different cohort of health care providers who developed varying levels of neutralizing antibodies to SARS-CoV-2 following vaccination,” Mallory noted. “That earlier cohort was tracked for several months post-vaccination and after booster administration, which allowed us to both investigate the breadth and duration of vaccine response to different SARS-CoV-2 variants of concern. This complex understanding of vaccine response, combined with findings of reduced booster uptake and rapid viral evolution, suggested an increased need for individuals to be informed of their protective antibody response status. This need has the potential to be met by at home using point-of-care tests that are much more accessible than complex laboratory tests.”

The researchers also assessed what happened after study participants received a booster shot. The groups with positive and negative results on the at-home antibody test both developed better antibody levels against current and potential future variants of COVID-19 following the booster.

“These findings allow us to draw connections between the complex, time-consuming and often expensive analyses that are done within central lab, clinical and academic research settings to measure the protective response to COVID-19 variants of concern,” Baric said, “As explored within the study, immunity is conferred through multiple exposure events to different viral antigens — either repeat vaccination, vaccination and breakthrough and natural infections — all of which strengthen the immune response to COVID-19 variants of concern. While the at-home tests don’t provide the level of specificity measured with more rigorous lab-based testing, they quickly inform populations about their general protective status and encourage a broader uptake of booster vaccinations as COVID-19 variants continue to circulate. Home testing should empower individuals who want to make informed decisions regarding their health care.”

Contact the UNC Gillings School of Global Public Health communications team at sphcomm@unc.edu.