In a new study from Michigan Medicine, researchers found that most patients with mild COVID-19 infections produce antibodies that persist and protect them from reinfection for up to six months.
Researchers analyzed nearly 130 people with COVID-19 illness between three and six months after initial infection.
Three patients were hospitalized while the rest were treated as outpatients and experienced mild infection, with symptoms including headaches, chills and loss of taste or smell.
They found approximately 90% of participants produced spike and nucleocapsid antibody responses, and all but one had persistent antibody levels at follow up.
In the study, the participants were either Michigan Medicine health care workers or patients with a high risk of exposure to COVID-19.
Most people took part in the same research team’s previous study, which found that COVID antibody tests are effective at predicting prior infection.
During the observation period, none of the people who produced antibodies were re-infected, compared to 15 antibody-negative patients.
The team also found that the antibodies’ ability 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.
While some studies have suggested antibodies against COVID-19 wane over time, these findings provide strong prospective evidence for longer-term immunity for those who produce an immune response to mild infection.
This is the first prospective study that demonstrates such a risk reduction for clinical reinfection in this specific type of population.
The team of researchers is now analyzing samples of this subject group taken up to a year after infection to further evaluate antibody responses.
If you care about COVID, please read studies about a new antiviral drug to treat COVID-19, flu, other viral infection and findings of these drugs may reduce COVID-19 death in older people.
For more information about COVID and your health, please see recent studies about green tea provides new hope to treat COVID-19 and results showing that fatigue, cognitive impairment and mood disorders linked to post-COVID-19 syndrome.
The study is published in Microbiology Spectrum. One author of the study is Charles Schuler, M.D.
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