June 14, 2021 – Cleveland Clinic last week shared research that provides insight into how the body’s natural immune system protects a person after a confirmed COVID-19 infection. The study followed Cleveland Clinic caregivers over five months as the vaccination process was beginning. The data showed that the vaccine was extremely effective in preventing COVID-19 infection, Cleveland Clinic says.
Interestingly, the researchers found that none of the previously infected employees who remained unvaccinated were re-infected over the duration of the study.
Cleveland Clinic says that this information could help guide vaccination efforts, should there be a shortage of vaccine supply as well as in countries where vaccine supply is limited.
While the news is welcome, Cleveland Clinic included note of caution about the results. “This is still a new virus, and more research is needed. It is important to keep in mind that this study was conducted in a population that was younger and healthier than the general population. In addition, we do not know how long the immune system will protect itself against re-infection after COVID-19. It is safe to receive the COVID-19 vaccine even if you have previously tested positive, and we recommend all those who are eligible receive it.”
According to the Wall Street Journal, more than 64% of Americans have received at least one vaccine dose and, of those who haven’t, roughly half have natural immunity from prior infection. Only around 10% of Americans have had confirmed positive COVID tests, but four to six times as many have likely had the infection.
The contribution of natural immunity should speed up the timeline for returning fully to normal. With more than 8 in 10 adults protected from either contracting or transmitting the virus, it can’t readily propagate by jumping around in the population. In public health, we call that herd immunity, defined broadly on the Johns Hopkins Covid information webpage as “when most of a population is immune.” It’s not eradication, but it’s powerful.
A February study in Nature used antibody screenings in late summer 2020 to estimate there had been seven times as many actual cases as confirmed cases. A similar study, by the University of Albany and New York State Department of Health, revealed that by the end of March 2020—the first month of New York’s pandemic—23% of the city’s population had antibodies. That share increased as the pandemic spread.
Without accounting for natural immunity, we are far from Anthony Fauci’s stated target of 70% to 85% of the population becoming immune through full vaccination. But the effect of natural immunity is all around us. The plummeting case numbers in late April and May weren’t the result of vaccination alone, and they came amid a loosening of both restrictions and behavior, WSJ says.