A U.K. study involving care home residents found that a prior COVID-19 infection reduces the risk of being infected by the virus again for several months. The study, which was published in Lancet Healthy Longevity, conducted antibody tests on 682 residents across 100 care homes in England in June and July of 2020.
About 1,429 staff also underwent antibody testing in that same time period. About a third of all study participants tested positive, suggesting prior COVID-19 infection. Beginning 90 days following the antibody testing, staff participants underwent weekly PCR testing, while resident participants were tested once per month.
Those who received a COVID-19 vaccine were removed from the study 12 days after their first dose.
Of the 634 staff and residents who had positive antibody results in June and July, reinfections were considered low. Only four residents and 10 staffers developed a second infection, suggesting about an 85% less likelihood among residents and about 60% less likelihood among staffers. Researchers cautioned that some staff may have been tested outside of their facility, which would not be included in the study data.
Still, researchers said the findings were encouraging.
“The fact that prior COVID-19 infection gives a high level of protection to care home residents is also reassuring, given past concerns that these individuals might have less robust immune responses associated with increasing age,” Dr. Maria Krutikov, lead author, said in a statement. “These findings are particularly important as this vulnerable group has not been the focus of much research.”
Dr. Laura Shallcross, a senior author on the study, said the next step would be to investigate the duration of immunity following natural infection and vaccination and to assess whether it stands against current and emerging variants.