Thanks to the Omicron surge this past winter, 3 in every 5 Americans have now been infected with COVID-19, a new government report shows.

Once Omicron surfaced as the predominant variant in this country, the highest infection rates were seen among children and teens, and the upward shift was steep: Only 1 in 3 Americans had been infected with COVID-19 by the time the variant took hold last December, the U.S. Centers for Disease Control and Prevention data found.

Since traditional disease surveillance methods do not capture all COVID cases because some people are asymptomatic, not diagnosed or not reported, the scientists analyzed tests that measured antibodies that are produced in response to COVID infection but not in response to COVID vaccines currently authorized in the United States, the researchers noted.

Despite the fact that far more Americans have now been infected with COVID, CDC officials stressed that vaccines remain critical.

“Having infection-induced antibodies does not necessarily mean you are protected against future infections,” Dr. Kristie Clarke, co-lead for the CDC’s COVID-19 Epidemiology & Surveillance Taskforce Seroprevalence Team, said during a media briefing Tuesday on the latest statistics.

“Previous infection has been shown to provide some protection against severe disease and hospitalization and vaccination either before or after infection provides additional protection. Additionally, we still do not know how long infection-induced immunity will last,” Clarke said.

“What we do know is that vaccination is a safe and effective way to get robust immune protection for specific amount of time,” she stressed. The “CDC continues to encourage all Americans to stay up to date with their COVID-19 vaccinations. And while those who are under the age of 5 are not yet eligible for vaccinations, the best way to protect them is to make sure that they are surrounded by people who are taking preventive measures like staying up to date with vaccines.”

In the study, published April 26 in the CDC publication Morbidity and Mortality Weekly Report, overall prevalence of COVID infection increased by only 0.9 to 1.9 percentage points per four-week testing period between September 2021 and December 2021.

But between December 2021 and February 2022, when the Omicron surge peaked, overall U.S. infection rates jumped from 33.5% to 57.7%. Over the same period, infection rates increased from 44.2% to 75.2% among children aged 0–11, and from 45.6% to 74.2% among those aged 12–17.

Meanwhile, infection rates increased from 36.5% to 63.7% among adults aged 18–49; from 28.8% to 49.8% among those aged 50–64, and from 19.1% to 33.2% among those 65 and older.

Even as these statistics show just how contagious the original Omicron variant was, a newer Omicron subvariant known as BA.2 is even more infectious, fueling a recent increase in both U.S. cases and hospitalizations, CDC data show.

“Overall, we continue to have some mixed trends,” CDC Director Dr. Rochelle Walensky said during the media briefing. “Deaths, fortunately, are continuing to trend downward with a seven-day average of about 300 per day, which represents an estimated 18% decline from the prior week. Hospital admissions also remain low at about 1,600 per day. But for the second week in a row, they are slowly trending upwards, [with] an increase of about 9% this week from the prior week.

“Cases also remained comparatively low to where we were even a month ago at about 44,000 per day, though this, too, has represented an increase of about 25% in the past week,” Walensky noted, adding that the CDC also knows that at-home rapid COVID test results are not captured in CDC data collection.

“Importantly, we continue to believe that those who are vaccinated and especially those who are boosted, continue to have strong protection against severe disease,” Walensky added.

More information

Visit the U.S. Centers for Disease Control and Prevention for more on COVID-19.

SOURCES: April 26, 2022, media briefing with: Rochelle Walensky, MD, director, U.S. Centers for Disease Control and Prevention, Kristie Clarke, MD, co-lead, COVID-19 Epidemiology & Surveillance Taskforce Seroprevalence Team; Morbidity and Mortality Weekly Report, April 26, 2022

Source: HealthDay