To address the pressing issue of diminishing immunity among older adults to COVID-19 as well to vaccines designed to protect against the virus, a $4.9 million award from the U.S. Centers for Disease Control and Prevention will fund a two-year project led by Brown University researchers and conducted by a team spanning multiple institutions.
The researchers will examine the duration of protective immunity in the context of emerging strains of COVID-19, releasing interim data to the CDC as it becomes available to inform policy decisions in real time.
Given rising case counts of the Delta variant, we need to know as soon as possible who needs a vaccine booster shot and when they need it. This information on how specific immunity to SARS-CoV-2 infection declines with aging, disease and in long-term care residents is critically important for developing a booster strategy based on real-time data in this population."
Stefan Gravenstein, co-lead investigator on the project and professor of geriatric medicine, Brown University
The CDC awarded the contract to Gravenstein; Elizabeth White, a Brown assistant professor of health services, policy and practice; and David Canaday at Case Western Reserve University. The project is based at Brown's Center for Long-Term Care Quality and Innovation, which focuses on research to improve care and quality of life for older adults living in nursing homes.
The new award builds on previous research about protective immunity over time conducted by Gravenstein and Canady. Their most recent study, published online in late August, found that COVID-19 antibodies produced by the Pfizer vaccine decreased sharply in nursing home residents and health care workers six months after receiving their second shots.
For that study, the research team studied blood samples of 120 nursing home residents and 92 health care workers. In particular, they looked at humoral immunity -; also called antibody-mediated immunity -; to measure the body's defenses against the coronavirus. The researchers, including a lab team at Harvard University, found that individuals' antibody levels decreased more than 80% after six months; the decline was similar in residents (median age 76) and health care workers (median age 48), according to the study. However, absolute antibody levels were much lower in the nursing home residents who had not also had a prior infection than the comparison groups.
After presenting their unpublished results directly to senior staff at the CDC, the researchers were urged to get the data out in the public domain as soon as possible to inform the decision-making process for booster vaccine recommendations. As a result, the researchers published the findings as a preliminary report ahead of peer review on medRxiv, an online preprint server for health sciences studies co-founded by Cold Spring Harbor Laboratory, Yale University and the BMJ, a global healthcare knowledge provider. The study is currently under review at a traditional peer-reviewed journal.
Another study by Gravenstein, Canaday and colleagues published last May found that within two weeks of receiving the second dose of vaccine and being considered "fully vaccinated," seniors who had not previously contracted the virus that causes COVID-19 mounted a substantially lower response to vaccine than experienced by younger health care workers. By six months after vaccination, 70% of these nursing home residents had blood test results showing a poor ability to neutralize the virus.
The preprint research is useful as the team continues to examine immunity in elderly patients.
"Aside from the obvious value of better understanding who and when to boost against SARS-CoV-2 infection, we've also substantially innovated in how to efficiently recruit and immunologically follow a long-term care population," Gravenstein said. "This methodological advancement leverages Brown's strengths in the intersection between biology, aging and public health research."
Results up to this point support the CDC's recommendation for booster shots -; especially for the elderly -; due to fading immunity, Gravenstein said. The team will now study 800 to 1,200 nursing home residents who have received one of the SARS-CoV-2 vaccines or who will newly receive a vaccine or booster, if and when boosters are federally recommended, and will assess their overall health and immune responses to see whether and how immunity to COVID changes over time. The team will continue to produce and share data in six-month segments.
As older residents in the study become re-vaccinated, Gravenstein said, this work will show whether that vaccination bolsters not just antibody levels and immediate protection, but also fortifies more durable defenses against new, incoming strains.
COVID-19 isn't going away, Gravenstein said -; if anything, it's becoming more like the flu in its persistency, and as the virus becomes more endemic to modern society, "this information on immunity will be critical to know."
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