Most Americans have COVID-19 antibodies as case numbers rise

Omicron surge appears to have caused many more infections than was reported

Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, answers questions at a Senate  hearing on Jan. 11. She said Tuesday that the increased number of young children with antibodies indicates high rates of COVID-19 infections. (Greg Nash/Getty Images Pool Photo)
Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, answers questions at a Senate hearing on Jan. 11. She said Tuesday that the increased number of young children with antibodies indicates high rates of COVID-19 infections. (Greg Nash/Getty Images Pool Photo)
Posted April 26, 2022 at 3:43pm

COVID-19 cases are slowly rising across the country as a new subvariant that first emerged in upstate New York picks up steam, and the Centers for Disease Control and Prevention thinks that many more Americans are contracting COVID-19 than reported.

Most Americans have already had COVID-19, however, and have antibody protection, according to a new study from the CDC released Tuesday. The percentage of people testing positive for antibodies increased from 34 percent in December 2021 to roughly 58 percent in February 2022. The study found that approximately three in four kids had COVID-19 antibodies after omicron, likely due to that population's low vaccination rates.

The agency will soon release a study showing that during the omicron surge, an estimated three infections occurred for every reported case, the CDC's Kristine Clarke told reporters. She is co-leader of the CDC's COVID-19 Epidemiology & Surveillance Taskforce Seroprevalence Team.

The numbers indicate that many more people contracted COVID-19 during the omicron surge than was reported. Public health officials have long suspected that outcome because many cases of COVID-19 are asymptomatic, or involve people doing at-home rapid tests and not reporting results.

Prior infection does not mean that an individual is fully protected against COVID-19, CDC officials warned. Protection wanes over time, and studies have shown that vaccinations are better at protecting against hospitalization than natural immunity.

Cases and hospitalizations are low compared to the height of the omicron surge but still moving upward. The U.S. is averaging about 1,600 hospital admissions per day for COVID-19, an increase of about 9 percent from last week, and about 44,000 cases per day, a 25 percent increase from the previous week, according to CDC Director Rochelle Walensky.

This rise in cases and transmission has also hit Capitol Hill. Sens. Ron Wyden, D-Ore., Christopher S. Murphy, D-Conn., and Vice President Kamala Harris tested positive for COVID-19. President Joe Biden is not considered a close contact of Harris because both have been traveling separately.

Essentially 100 percent of cases across the U.S. are now lineages or sublineages of omicron, the CDC said. The original omicron variant, BA.1, now only makes up 3 percent of sequenced cases, and the more transmissible BA.2 makes up 68 percent of circulating cases.

The latest subvariant, BA 2.12.1, makes up about 30 percent of sequenced cases, and Walensky says it appears to be about 25 percent more contagious than the BA.2 variant. Scientists are still trying to determine how the new subvariant impacts vaccine effectiveness. But they say that vaccines protect against severe disease from BA.2.12.1

More infections for kids

The number of children with antibodies increased dramatically during the omicron wave. Before omicron hit in December 2021, roughly 44 percent of kids 11 and under had COVID-19 antibodies, but that rose to more than 74 percent after omicron peaked in February 2022.

Walensky said the big jump in antibody protection among kids signifies a high rate of infection in young children during the omicron wave. Kids were more likely than adults to get infected with COVID-19 because many are unvaccinated or ineligible for vaccines.

Vaccination rates remain low in kids aged 5 to 11, as just 35 percent have received one dose and 28 percent are fully vaccinated.

Peter Marks, director of the Center for FDA Biologics Evaluation and Research, told senators Tuesday that the agency plans to publish a tentative advisory committee timeline for discussions on COVID-19 vaccines for kids under 5 in the next week, but indicated that manufacturer applications were still not complete.

Marks told Senate Health, Education, Labor and Pensions Chair Patty Murray, D-Wash., that he couldn't publicly say exactly what is holding up the emergency use authorization. Vaccine manufacturers typically announce when they have submitted a full and complete application for emergency use.

"We will proceed with all due speed once we have complete applications. Some of these are complicated because they are relatively larger, covering larger swaths of the pediatric population than others," Marks told Murray.

Murray's questions came a day after House Select Committee on the Coronavirus Chairman James E. Clyburn, D-S.C., requested a briefing on the status of COVID-19 vaccines for young children. The request comes in response to the reports that Moderna is holding its vaccine until early summer. Moderna reportedly plans to apply for emergency authorization by the end of this month, and Pfizer is likely to request authorization in June.

Lauren Clason contributed to this report.