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About 58 percent of the US population has antibodies that resulted from COVID-19 infections, according to new data from the US Centers for Disease Control and Prevention. 

December’s rise of the Omicron variant caused a huge swell of coronavirus infections in the US. So many people have been infected that the proportion of Americans who have anti-N antibodies, a type of antibody that shows up in the blood post-COVID infection but not after vaccination, rose from 34 percent of the population in December to 58 percent in February. 

The highest bump occurred in the youngest cohorts. In December, 44 percent of children aged 0 to 11 years had natural antibodies. As of February, that figure has risen to 75 percent.

The CDC reported its figures on Tuesday, which are based on blood samples tests from a commercial lab network. The agency analyzed about 74,000 blood samples every month from September 2021 to January 2022, and 46,000 samples in February 2022, to arrive at its results. 

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The biggest increases in natural antibodies occurred in the cohorts with the lowest vaccination rates—young children—further emphasizing the need to vaccinate those who remain the least protected. Children aged 5 or older are eligible to receive Pfizer-BioNTech shots, though only 35 percent of kids ages 5 through 11 have received at least one vaccine dose. Children ages 0 to 4 are still ineligible for any COVID-19 vaccines.

While the lab results show how much of the population has been infected by SARS-CoV-2, they cannot tell us whether these antibody levels are high enough to protect people against future infection, said the CDC according to CNBC. CDC director Rochelle Walensky cautioned that the level of protection people receive post-infection is more uncertain than the level you receive from vaccines—vaccination is still the safest and most assured way to protect yourself against the virus. 

Natural immunity from infection wanes faster than immunity gained from vaccines, according to Johns Hopkins University. A CDC report from October 2021 says getting vaccinated for the coronavirus when you’ve already had COVID-19 significantly boosts immune protection and reduces risk of reinfection. And an earlier 2021 study showed that you are twice as likely to get reinfected with the coronavirus if you are not vaccinated.

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