Coronavirus has infected more than half of Americans, reports CDC

Sixty percent of Americans, including 75 percent of children, were infected with the coronavirus in February, federal health officials said Tuesday — another notable milestone in a pandemic that continues to confound expectations.

The highly contagious Omicron variant was responsible for much of the toll. In December 2021, when the variant began to spread, only half of people had antibodies indicating previous infection, according to new research from the Centers for Disease Control and Prevention.

While the numbers came as a shock to many Americans, some scientists said they expected the numbers to be even higher, given the contagious variants that have marched across the country over the past two years.

There could be good news in the data, some experts said. A gain in population-wide immunity can provide at least a partial bulwark against future waves. And the trend may explain why the surge that is now roaring in China and many European countries has been muted in the United States.

A high percentage of past infections could also mean that there are now fewer cases of life-threatening illness compared to infections. “We’re going to see less and less severe disease and more and more a shift to clinically mild disease,” said Florian Krammer, an immunologist at the Icahn School of Medicine at Mount Sinai in New York.

“It will be increasingly difficult for the virus to do serious damage,” he added.

Government officials also believe the data heralds a new phase of the pandemic in which infections can be common at times but cause less harm.

At a press conference on Tuesday, Dr. Ashish Jha, the new White House Covid coordinator, said stopping infections “was not even a political goal. The objective of our policy should be: obviously, to minimize infections wherever possible, but to ensure that people do not get seriously ill.”

The average number of new confirmed cases per day in the United States — more than 49,000 as of Monday, according to a New York Times database — is comparable to levels last seen in late July, even as cases have increased by more than 50% in the last two weeks, a trend that infectious disease experts attributed to the new Omicron subvariants.

Dr. Jha and other officials warned against complacency and urged Americans to continue receiving vaccines and booster shots, saying antibodies from previous infections do not guarantee protection against the virus.

During the Omicron outbreak, infections rose most sharply among children and teens, according to the new research. Past infections have increased least among adults aged 65 and over, who have the highest vaccination rates and may be more likely to take precautions.

“Evidence of past Covid-19 infections has increased substantially across all age groups,” Kristie Clarke, an agency researcher who led the new study, told a news conference Tuesday.

The widespread infection raises a worrying prospect: a potential spike in cases of long-term Covid, a poorly understood constellation of persistent symptoms.

Up to 30% of people infected with the coronavirus may have persistent symptoms, including worrisome changes to the brain and heart. Vaccination is believed to reduce the chances of long-term Covid, although it is unclear by how much.

“The long-term impacts on health care are unclear, but it’s certainly worth taking very seriously, as a fraction of people will be struggling for a long time with the consequences,” said Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Medicine. Public Health.

Even a very small percentage of infected or vaccinated people who develop Covid would translate into millions across the country.

While the focus is often on preventing the healthcare system from buckling under an outbreak, “we should also be concerned that our healthcare system is overwhelmed by the ongoing healthcare needs of a population with Covid for a long time,” said Zoë McLaren, a health specialist. health policy expert at the University of Maryland, Baltimore County.

There are still tens of millions of Americans without immunity to the virus and they remain vulnerable to the short- and long-term consequences of the infection, said Dr. Tom Inglesby, director of the Center for Health Security at Johns Hopkins Bloomberg. School of Public Health.

“Betting you’re in the 60% is a big gamble,” he said. “For anyone who hasn’t been vaccinated and boosted, I would take this new data as a direct message to either do this or hope the virus is likely to catch up with you if it hasn’t already.”

Although cases are on the rise again, especially in the Northeast, the increase in hospitalizations has been minimal and deaths are still falling. According to the agency’s latest criteria, more than 98% of Americans live in low- or medium-risk communities.

Even among those who are hospitalized, “we’re seeing less oxygen use, fewer ICU admissions, and fortunately, we haven’t seen any increases in deaths associated with them,” said CDC Director Dr. Rochelle Walensky. “We expect the positive trends to continue.”

The country has seen a roughly five-fold drop in PCR tests for the virus since the peak of Omicron, and so tracking new cases has become difficult. But the reported count is much lower, about 70 times lower, said Dr. Walensky, reflecting “a true and reliable drop in our general cases”.

New subvariants of Omicron, called BA.2 and BA.2.12.1, supplanted the previous iteration, BA.1, which began circulating in the country in late November and sent cases to record levels in a matter of weeks.

“Of course, even more have been infected now, because BA.2 will have infected some who have avoided it until now,” said Dr. Hanage.

By February, three of the country’s four children and teenagers had already been infected with the virus, compared with a third of older adults, according to the new study.

The fact that so many children are carriers of antibodies can offer comfort to parents of children aged 5 and younger who do not qualify for vaccination, as many may have acquired at least some immunity through the infection.

But Dr. Clarke urged parents to immunize children who qualify once regulators have approved a vaccine for them, regardless of their previous infection. Among children hospitalized with the virus, up to 30% may need intensive care, she noted.

While many of these children also have other medical conditions, about 70% of cases of multisystem inflammatory disease, a rare consequence of Covid-19 infection, occur in healthy children.

“As a pediatrician and a parent, I would absolutely endorse children being vaccinated, even if they have been infected,” said Dr. Clarke.

Some experts said they were concerned about the long-term consequences, even in children with mild symptoms.

“Given the very high proportion of infection in children and adults that happened earlier this year, I am concerned about the rise in long-term Covid cases as a result,” said Akiko Iwasaki, a Yale University immunologist who studies the disease.

To measure the percentage of the population infected with the virus, the study relied on the presence of antibodies produced in response to an infection.

CDC researchers began assessing antibody levels in people at 10 sites early in the pandemic and have since expanded that effort to all 50 states, the District of Columbia and Puerto Rico. The investigators used a test sensitive enough to identify people previously infected for at least one to two years after exposure.

The researchers analyzed blood samples taken from September 2021 to February 2022 for antibodies to the virus, then analyzed the data by age, sex and geographic location. The researchers specifically looked for a type of antibody produced after infection but not after vaccination.

Between September and December 2021, the prevalence of antibodies in the samples steadily increased by one to two percentage points every four weeks. But it jumped sharply after December, rising nearly 25 points through February 2022.

The percentage of samples with antibodies increased from about 45% among children aged 11 years and under and among adolescents aged 12 to 17 years to about 75% in both age groups.

As of February 2022, about 64% of adults aged 18 to 49, about 50% of those aged 50 to 64, and about 33% of seniors have been infected, according to the study.

Despite the record of cases during the Omicron outbreak, the reported statistics may not have captured all infections, because some people have few or no symptoms, may not have opted for testing, or may have tested themselves at home.

According to an upcoming CDC study, there could be more than three infections for every reported case, said Dr. Clarke.

Noah Weiland contributed reports from Washington.

Leave a Reply

Your email address will not be published.