Natural Immunity Lasts for at Least 18 Months: Study

A new study in 2022 found that a neutrophil-associated cationic protein contained in saliva can prevent Covid-19 infection. This image shows a 3D print of a spike protein of SARS-CoV-2—the virus that causes COVID-19—in front of a 3D print of a SARS-CoV-2 virus particle. Courtesy of NIAID/RML

The protection people experience after recovering from COVID-19, known widely as natural immunity, lasts for at least 18 months, according to a recently published study.

Researchers in Italy analyzed the level of antibodies in 36 patients who were documented as contracting COVID-19 in March 2020. About half of the patients went on to get COVID-19 vaccines, but the rest remained unvaccinated. Samples from all but two were tested at timed intervals, ending in September 2021, using assays that have received clearance from the U.S. Food and Drug Administration.