A new study has shown that most patients with mild COVID-19 infections produce antibodies that remain and protect them from re-infection for up to six months.
The results of the Michigan Medicine study were published in the journal Microbiology Spectrum.
Researchers analyzed nearly 130 patients with PCR-confirmed COVID-19 disease between three and six months after the first infection. Three patients were hospitalized while the rest were treated as outpatients and experienced mild infection, with symptoms such as headache, chills and loss of taste or smell.
The results revealed that approximately 90 percent of the participants produced nail and nucleocapsid antibody responses, and all but one had persistent antibody levels at follow-up.
“In the past, there was a lot of concern that only those with severe COVID-19 produced strong antibody responses to infection,” said Charles Schuler, MD, lead author of the journal and clinical assistant professor of allergy and immunology at Michigan Medicine.
“We show that people with mild attacks of COVID-19 did really well after the infection, made antibodies and kept them,” Schuler added.
The participants in the prospective study were either healthcare professionals from Michigan Medicine or patients at high risk of exposure to COVID-19. Most subjects participated in the same study group’s previous study, which showed that COVID antibody tests are effective in predicting previous infection.
During the observation period, none of the subjects who produced antibodies were infected, compared to 15 antibody-negative patients. Schuler’s team also found that the ability of the antibodies to neutralize COVID-19 did not differ significantly from the first visit, which occurred three months after infection, to the second visit at the six-month mark.
“Although some studies have suggested that antibodies to COVID-19 diminish over time, these findings provide strong potential evidence for longer immunity for those who produce an immune response to mild infection,” said James Baker Jr., MD, senior author of the journal and founding director. for the Mary H. Weiser Food Allergy Center at Michigan Medicine.
“To the best of our knowledge, this is the first prospective study showing such a reduction in the risk of clinical reinfection in this specific type of population,” added Baker Jr.
The research group is now analyzing samples from this group of subjects that were taken up to one year after infection to further evaluate antibody responses. At the same time, they concluded that individuals with COVID-19 may delay vaccination for 90 days after the infection has ended.
The Centers for Disease Control and Prevention recommends that those treated with monoclonal antibodies or convalescent plasma wait 90 days after receiving treatment before being vaccinated, and others should wait until they have recovered from COVID-19 and “have met the criteria for discontinuation. the insulation. “
A study conducted in Kentucky showed that unvaccinated people who already had COVID-19 were 2.34 times more likely than fully vaccinated to become infected again, suggesting that “vaccination provides additional protection against re-infection.”
In addition, the research was conducted between March 2020 and February 2021, months before the highly transferable Delta variant became the dominant strain of Covid in the United States.
Among increasing cases and hospitalizations, Schuler says, remaining unvaccinated comes with “a high price” for immunity.
“These results are encouraging for those who have already run the glove for COVID-19 infection,” he said.
“However, I do not recommend citing this study as a reason not to vaccinate for those who have never been infected before. Vaccination reduces the risk of infection, hospitalization and death of COVID-19, without having the actual infection. Achieve natural immunity by shooting “Vaccination in favor of infection is not worth going through the discomfort, the risk to yourself and the risk to others,” he concluded.
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