The agency found 10 patients across four states who fell sick with the omicron variant within three months of a previous infection from the delta variant between October 2021 and January. The timing intervals between infections ranged from as few as 23 days to up to 87 days.
Seven of the patients were unvaccinated. Only one of the remaining three was considered “up to date” on their shots by CDC standards.
Cartoons on the Coronavirus
The report documented a small pool of reinfected individuals who were relatively young, so its findings “might not be generalizable to the U.S. population,” researchers stated. The median age of the group at first infection was 11 years old.
“Nonetheless, this study highlights potential limits of infection-induced immunity against novel variants,” they continued.
Nine of the patients were symptomatic during their first infection. Of the data available for eight of the patients during their second infection, six were symptomatic during reinfection.
The report concluded that “although the epidemiology of COVID-19 might change as new variants emerge, vaccination remains the safest strategy for preventing future SARS-CoV-2 infections.”
Reinfections became especially more common during the surge of the omicron variant, which sent coronavirus cases and hospitalizations to record levels. However, early reinfections have not been well studied and not much is known about their occurrence.
A small Danish study published in February suggested that the omicron subvariant BA.2, or “stealth omicron,” can reinfect people shortly after they recover from the more common lineage of omicron, though the occurrence is “rare” and is seen “mostly in young unvaccinated individuals with mild disease not resulting in hospitalization or death.”
Due to rapid tests taken at home and limited capacity for strain testing in general, “most early reinfections are likely not identified,” the CDC report stated.