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CDC director says high immunity in US population offers some protection against omicron BA.2

CDC Director Rochelle Walensky said Tuesday there is enough immunity in the U.S. population to provide some protection against the more contagious omicron BA.2 subvariant, which could help stave off another wave. of Covid which is slamming hospitals.

“The high level of population immunity against vaccines, boosters and previous infections will provide some level of protection against BA.2,” Walensky said during a Covid briefing at the White House. White House chief medical adviser Dr. Anthony Fauci said last month that infections could rise due to BA.2, but he doesn’t expect another surge.

BA.2 now accounts for 72% of circulating Covid variants in the United States, according to the Centers for Disease Control and Prevention. It quickly replaced the earlier version of omicron, BA.1, which caused the massive wave of infection over the winter. In early February, BA.2 accounted for about 1% of Covid variants in the United States

BA.2 is now the dominant variant of Covid in all regions of the country, with the highest circulation in the densely populated Northeast, a repeated epicenter of the pandemic in the United States. BA.2 represents more than 80% of the variants in circulation in New England. , New York, New Jersey, Puerto Rico and the Virgin Islands, according to the CDC.

According to a CDC survey of samples from blood donors, about 95% of the U.S. population ages 16 and older had developed antibodies to the virus through vaccination or infection by December. However, simply having antibodies against the virus does not necessarily stop an infection. Omicron, with its many mutations, has an increased ability to infect both vaccinated and previously infected people.

However, vaccinated, boosted and those who have recovered from previous infection all have high levels of protection against BA.2 hospitalization, according to a study published by Qatar scientists affiliated with Weill Cornell Medicine in Doha. . The study has not been peer reviewed.

Scientists found that people who received three injections of Pfizer had the highest protection against BA.2 hospitalization at 98%. People who received two doses of Pfizer and those who recovered from a previous infection had similar levels of protection against hospitalization at 76% and 73% respectively. People who had received two doses of Pfizer and recovered from a breakthrough infection had 97% protection.

The data suggests that even if BA.2 is fueling an increase in infections in the United States, there may be enough immunity in the population to prevent a major outbreak of serious illness that overwhelms hospitals.

BA.2 is 30-80% more transmissible than the previous version of omicron, according to public health authorities in the UK and Denmark. Scientists from the UK, South Africa and elsewhere have found that BA.2 generally does not make people sicker than BA.1, which was less severe than the delta variant.

BA.2 fueled outbreaks in Europe, including the UK and Germany. China is battling its worst surge since 2020, locking down major cities like Shanghai.

However, Covid infections in the United States are stable at the moment, even though BA.2 represents a growing proportion of virus variants circulating in the country. The United States reported an average of about 25,000 new infections on Monday, down 4% from the previous week, CDC data shows. However, new infections are likely underreported because many people use home tests that aren’t captured by data.

The number of people hospitalized with Covid fell to the lowest since 2020. More than 10,700 patients were hospitalized with the virus on Tuesday on a seven-day average, a 92% drop from the peak of the omicron wave in January, according to data from the Department of Health and Human Services.

The CDC has adjusted its Covid guidelines to focus more on hospitalizations as a measure of the severity of the virus’ impact on the country. More than 97% of the US population lives in counties with low to moderate levels of Covid, meaning people don’t need to wear masks under CDC guidance.


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