Whether past infection provides protection against new circulating variants remains unclear.
A study Tuesday by the Centers for Disease Control and Prevention indicates three in five Americans have had been infected with the virus that causes COVID-19, up from one in three last fall, indicating how easily the omicron variant spread through the country over the winter.
But CDC officials cautioned that the findings should not be interpreted to mean that people with evidence of prior infection are protected from reinfection in the future, and continued to urge people to get vaccinated or a booster if eligible. It examined seroprevalence from September 2021 through February 2022 by age group ational survey that estimates the proportion of the population in the 50 U.S. states, the District of Columbia and Puerto Rico who were infected. Overall, it increased from 33.5% to 57.7% over the study period.
Vaccination rates are higher among older people, perhaps explaining the lower numbers of prior infections among them, but the study also noted that they may be more careful than younger people about protecting themselves by avoiding crowded situations and wearing masks. “Having antibodies doesn’t necessarily mean you are protected against infection,” Clarke said in a news briefing. “Vaccination provides additional protection.”