TUESDAY, Feb. 1, 2022 (HealthDay News) — Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody tests should not be used for diagnosis of infection nor to predict natural immunity against reinfection, and, prior to emergence of the delta and omicron variants, individuals with recent SARS-CoV-2 infection had strong protection against symptomatic reinfection for at least seven months, according to a practice points guideline and a review, respectively, published online Jan. 25 in the Annals of Internal Medicine.
Amir Qaseem, M.D., Ph.D., from the American College of Physicians in Philadelphia, and colleagues updated rapid practice points to summarize the available evidence on antibody response to SARS-CoV-2 infection and protection against reinfection. The authors note that SARS-CoV-2 antibody tests should not be used for diagnosis of SARS-CoV-2 infection. Furthermore, antibody tests should not be used to predict the degree or duration of natural immunity conferred by antibodies against reinfection.
In a related review, Mark Helfand, M.D., M.P.H., from the VA Portland Healthcare System in Oregon, and colleagues synthesized evidence on protection against reinfection after SARS-CoV-2 infection. The researchers found that reinfection risk varied from 0 to 2.2 percent across 18 eligible studies. Compared with unvaccinated, previously uninfected individuals, in those with recent SARS-CoV-2 infection, 80 to 98 percent of symptomatic infections with wild-type or alpha variants were prevented. Protection remained above 80 percent for seven months or more; none of the studies followed patients after the emergence of the delta variant or the omicron variant.
“Our results do not in any way argue for infection rather than vaccination as a means of obtaining individual or herd immunity,” Helfand and colleagues write. “Nor do our results provide evidence that immunity acquired by infection is longer-lasting or in other ways superior to immunity acquired by vaccination.”
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