Long-Term Care Residents Mount Antibodies to COVID Vaccines

Elderly residents of long-term care facilities mount a detectable antibody response to COVID-19 vaccination, according to a recently conducted survey of UPMC Senior Community residents. Because it’s not yet known how long the antibodies persist, the authors’ urged continual monitoring for COVID-19 symptoms and cautioned that there’s still a need for controlled reopening of the facilities.

In order to share vital information and guide safe, timely reopening of long-term care facilities, UPMC and University of Pittsburgh School of Medicine clinician-scientists are publishing the findings in medRxiv, a preprint journal, ahead of peer-reviewed publication.

“COVID-19 hit long-term care facilities hard and caused the untimely death of hundreds of thousands of senior citizens in the U.S.,” said lead author David Nace, MD, MPH, chief medical officer of UPMC Senior Communities and associate professor in Pitt’s Division of Geriatric Medicine. “So, these facilities have been understandably reluctant to remove infection prevention measures. But we know that social interaction is important at all stages of life, and particularly in older age. Our study gives some cautious good news, while pointing to knowledge gaps that will need more research.”

The clinician-scientists stress that having the antibodies detected by these tests does not conclusively mean that the person cannot get COVID-19.

“This shows that most are mounting an antibody response, but it does not tell us if that response is adequate to fight off the virus if they encounter it,” said senior author Alan Wells, MD, DMSc, medical director of UPMC Clinical Laboratories, the Thomas Gill III Professor of Pathology in Pitt’s School of Medicine, and a faculty member of the McGowan Institute for Regenerative Medicine. “These antibody tests were designed to tell us if someone had previously encountered the virus, but we are using them to gain insight into vaccine response. Theoretically, having vaccine-induced antibodies will protect against the virus, but we’ll need studies that follow long-term care residents over time before we can be confident saying how well and for how long vaccines offer protection.”

There have been more than 1.4 million cases of COVID-19 in U.S. nursing homes, resulting in 175,000 COVID-19-related deaths, or 34% of all U.S. deaths from the disease. Visitation restrictions at these facilities and the curtailing of community activities were necessary to slow the spread of the virus, and, so far, there is no consensus around reopening strategies.

Between March 15 and April 1, Dr. Nace and his colleagues tested blood from 70 residents of assisted living, personal care and independent living facilities who voluntarily participated in the study and were not on immunosuppressive therapies. All of the residents had been fully vaccinated with either the Moderna or Pfizer two-dose vaccines. They found that all 70 residents had detectible antibodies against SARS-CoV-2, though of variable levels, as measured by two different commercially available antibody tests.

The UPMC–Pitt study was too small to draw statistically significant conclusions on the characteristics of residents who had the strongest antibody response, but participants who had previously tested positive for COVID-19 tended to have higher antibody levels. Conversely, participants who were male, older, taking steroid medications or for whom a longer period of time had passed since vaccination tended to have lower levels.

The elderly typically have a less robust response to some vaccines, including the seasonal influenza vaccine, which tends to wane in effectiveness over the course of several months. Ongoing adaptive immunity—an immune response that involves more than just antibodies—also is known to be decreased in older people.

“Whether older people have a waning immunity to the COVID-19 vaccine that is similar to the flu vaccine remains to be determined,” said Dr. Nace. “So, while I think cautious reopening of long-term care facilities shortly after mass vaccination can be done, I would couple it with continuous monitoring for COVID-19 symptoms. If someone has symptoms, I’d test them immediately, whether they were vaccinated or not, because prompt treatment with monoclonal antibodies could prevent hospitalization and death.”