NEW YORK (AP) – Three out of four children in the United States have been infected with coronavirus and more than half of all Americans have had signs of previous infections, researchers at the Centers for Disease Control and Prevention said in a report Tuesday.
Researchers tested blood samples from more than 200,000 Americans and looked for antibodies to fight viruses made from infections, not vaccines. They found that signs of a past infection increased dramatically between December and February, when the more contagious version of omicron invaded the United States.
For Americans of all ages, about 34% had signs of a previous infection in December. Just two months later, 58% did.
“I expected it to increase. I didn’t expect it to increase that much, “said Dr. Christy Clark, co-leader of a CDC team that monitors the extent of coronavirus infections.
The news came when Pfizer sought permission to offer a booster dose to children ages 5 to 11, just as people ages 12 and older can receive.
According to the CDC report, the most notable increase is in children. The percentage of those under 17 with antibodies rose from about 45% in December to about 75% in February.
The older people were, the less likely they were to have a history of past infections. This may be due to the fact that older people have a higher vaccination rate and are more likely to take other precautions against COVID-19, such as wearing masks and avoiding crowds, Clark said.
The reported cases of COVID-19 had a huge jump in December and January, after which they decreased almost as dramatically as they increased. But the daily number of cases has risen again in recent weeks.
The number of cases is thought to have been reduced, but officials believe the recent increases reflect a real increase in infections. Many COVID-19 infections are mild enough that patients do not seek care or confirmatory laboratory tests. CDC officials say they plan to launch a study soon, which says there have been three infections in recent months for every reported case.
Another recent trend: US health officials say they have seen a two-week increase in hospitalizations with COVID-19, although numbers remain relatively low. The hospital admission is about 1,600 a day, an increase of 9% in the previous week, the CDC said.
However, the available evidence gives reason to hope for how the pandemic is going, officials suggest.
“We do not expect a more serious illness from some of these sub-options, but we are actively studying them,” CDC Director Dr Rochelle Valenski said on Tuesday.
Tests that show how many people have had previous infections can detect antibodies in one to two years after infection, and possibly longer. Studies show that a previous infection may protect some people from serious illness and hospitalization, but CDC officials have stressed that previously infected people should be vaccinated against COVID-19.
The test looks for any detectable level of antibodies; did not distinguish how many people have levels of antibodies that may be protective. Scientists are still trying to understand what role these types of antibodies play in protecting against future exposure to viruses.
Officials continue to call on Americans to receive vaccines and boosters that offer additional protection against COVID-19 for everyone, including those who have previously been infected.
The United States is currently offering a booster dose starting at age 12, but Pfizer and BioNTech on Tuesday asked the Food and Drug Administration to allow healthy young children to receive one as well – about six months after their last injection. The companies cite a small study showing that an additional injection for children aged 5 to 11 increases antibodies capable of fighting the over-infectious version of omicron. Pfizer children’s photos are one-third of the dose given to everyone 12 years of age or older.
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AP medical writer Laurent Niergor of Washington contributed to the report.
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The Associated Press’s Department of Health and Science receives support from the Howard Hughes Medical Institute’s Department of Scientific Education. AP is solely responsible for all content.
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