More than half of Americans have had COVID infections -antibody study

Following the record surge in COVID-19 cases during the Omicron-driven wave, some 58% of the U.S. population overall and more than 75% of younger children have been infected with the coronavirus since the start of the pandemic, according to a U.S. nationwide blood survey released on Tuesday.

The study of blood samples sent to laboratories between December and February - when Omicron cases were raging - showed children, many of whom remain unvaccinated, had the highest rates of infection during that surge, while people 65 and older - a heavily vaccinated population - had the lowest.

Scientists looked for specific antibodies produced in response to the SARS-CoV-2 virus that are only present after an infection and are not generated by COVID-19 vaccines.

In children aged 11 and younger, 75.2% were positive for infection-related antibodies from December to February, up from 44.2% in the prior three month period.

In children aged 12-17, 74.2% carried antibodies, up from 45.6% between September and December. The overall rate was 33.5% for the entire population during that earlier time period.

"Having infection-induced antibodies does not necessarily mean you are protected against future infection," said Kristie Clarke of the U.S Centers for Disease Control and Prevention (CDC) during a media briefing to discuss the data. "We did not look at whether people had a level of antibodies that provides protection against reinfection or severe disease."

The CDC stressed that vaccination remains the safest strategy for preventing complications from COVID-19.

Samples were collected from commercial laboratories testing blood for reasons unrelated to COVID-19, such as routine medical care. Traditional methods of disease surveillance do not capture all COVID-19 cases because some are asymptomatic, not diagnosed, or not reported, the CDC said.

The median sample size per four-week period was 73,869 collected between September and January. That fell to 45,810 in February.

Overall, U.S. COVID-19 infections have reached 80.8 million, with a 22.7% increase over the last week, and hospital admissions rose 6.6% from the prior week.

While deaths fell 13.2%, week-over-week, the United States is fast approaching the grim milestone of 1 million total COVID-related deaths.

More than 66% of the U.S. population is considered to be fully vaccinated against COVID-19, according to federal data. Nearly 46% of those Americans had so far also received a booster dose.