An unvaccinated teenager who tested positive for the COVID-19 Delta variant last year was re-infected with the Omicron variant in as little as 23 days, according to a case study that looked at potential limitations of “infection-induced” immunity from COVID-19.
That examination of the US Centers for Disease Control and Prevention (CDC) analyzed 10 individuals who reported “early re-infections” or those who tested positive for the Omicron variant within 90 days of testing positive for the Delta variant. Delta was the dominant tribe in the United States until Omicron took over in December 2021.
Among the 10 people surveyed – five from Vermont, three from Wisconsin, one from the state of Washington and one from Rhode Island – the shortest time between infections was the teenager in Washington with 23 days. The longest was 87 days.
Eight of the subjects studied were younger than 18, and only one had received a whole series of COVID-19 vaccines. They were not eligible for a booster at the time of re-infection. No other patient was updated with recommended COVID vaccines.
The CDC says vaccinations provide additional protection against COVID-19 even if you have been infected before.
The agency warns that the results “may not be generalized to the U.S. population,” and the data is limited to the transition period in which Omicron surpassed Delta as the dominant U.S. tribe.
“Nevertheless, this study highlights potential limits of infection-induced immunity to new variants,” the study concludes. “Although the epidemiology of COVID-19 may change as new variants emerge, vaccination remains the safest strategy.”
The study was published about a week before a The Florida judge ended the extensive federal mask mandate on planes, trains and in transit hubs, the last of major pandemic rules at the federal level. The Justice Department said it will not appeal the judge’s decision unless the CDC believes the claim is still necessary.
On Tuesday, the CDC had not made a decision.
Newly reported US cases of COVID-19 are relatively low compared to the last two years, but they have risen recently and are probably a minority. Hospital admissions are nearly flat, and deaths are still declining, according to the Associated Press.