Federal health officials sounded the alarm on Friday about a much more contagious variant of the coronavirus that is projected to become the country’s dominant source of infection in March, potentially fueling another outbreak of cases and deaths.
In a study released on Friday, the Centers for Disease Control and Prevention said their predictions indicated that outbreaks caused by the new variant could lead to a growing pandemic this winter. He called for a reduction in preventive measures, including more intensive vaccination efforts across the country.
The variant is not known to be more deadly or to cause more serious illnesses. But the dire warning – protected by limited data on how prevalent the variant first identified in Britain has become – fell in a week when the country’s vaccination campaign was hampered by confusion and limited supplies, as demand was growing among an increasing number of eligible people
Only 76 cases of the variant have so far been identified in the United States, but the real number is believed to be higher and expected to grow in the coming weeks, officials said. They emphasized that current mitigation strategies were effective against the new strain, urging Americans to be vigilant when wearing face masks, keeping two meters or more away from other people, washing their hands frequently, reducing interactions with people outside their homes, limit contacts and avoid crowds.
But the rise in cases threatens to paralyze already overburdened hospitals and nursing homes in many parts of the country. Some are at or near full capacity Others have experienced worrying rates of infection among their staff, causing shortages and increasing the patient load.
“I want to emphasize that we are deeply concerned that this strain is more transmissible and could accelerate outbreaks in the United States in the coming weeks,” said Dr. Jay Butler, deputy director of infectious diseases at the CDC. “We are sounding the alarm and asking people to realize that the pandemic is not over yet and it is by no means time to throw in the towel.”
“We know what works and what to do,” he said.
Covid’s cases and deaths broke record after record across the country, with a maximum number of deaths, 4,400, announced on Tuesday. At least 3,973 new deaths and 238,390 new cases were reported on Thursday, and the country is close to the 400,000 death mark.
One in 860 Americans died of Covid-19 last year, according to new figures released by the CDC. But the death toll has not dropped equally among races, ethnicities and geographic regions, and there is a concern that vaccines will not reach the most affected communities, where access to health services is limited and mistrust is growing.
The new variant, called B 1.1.7, was first identified in Britain, where it quickly became the main source of infections, accounting for up to 60% of new cases diagnosed in London and surrounding areas.
Since then, it has been detected in at least 30 countries, including the United States and Canada. In the United States, it accounts for less than 0.5 percent of cases, based on the analysis of a limited number of samples.
Other variants circulating in South Africa and Brazil are also considered more contagious, but have not yet been identified in the United States. Japanese officials said this month that they had detected one of the variants in four passengers arriving from Brazil.
The CDC had previously announced that, as of January 26, all air passengers arriving in the United States, regardless of their vaccination status, would be required to provide proof of a negative coronavirus test or Covid recovery test.
In the new report, CDC scientists modeled how quickly the variant can spread in the United States, assuming that about 10 to 30 percent of people have pre-existing immunity to the virus, and another million people will be vaccinated each week from this month.
If the variant is about 50% more contagious, as suggested by data from Britain, it will become the predominant source of all infections in the United States in March, the model showed. A slow release of vaccines will accelerate that fate.
The variant differs in about 20 mutations from previous versions of the virus, including at least two mutations that can contribute to its greater contagiousness. As of Jan. 13, it was detected in 76 cases in 12 states, but the actual numbers are likely to be much higher, Butler said. “The CDC expects these numbers to increase in the coming weeks,” he said.
State and local laboratories have pledged to sequence about 6,000 samples a week, a goal the agency hopes to achieve in about three weeks.
Agency officials also warned that standard tests for the virus could lose one of the altered genes in the new variant. This should not be a problem for most laboratory tests, they said, but some antigen tests can produce “false negatives”, with cases of infection missing.
“So far, we haven’t found evidence of that, but we’re looking at it more closely,” said Butler.
It is not yet clear what makes the new variants more contagious. They share at least one mutation, called N501Y, which is believed to be involved. One possibility, the researchers said, is that the mutation may increase the amount of virus in the nose, but not in the lungs – potentially explaining why it is more contagious, but not more deadly.
A greater amount of virus in the nose means that any infected person would expel more virus while talking, singing, coughing or even breathing, said Trevor Bedford, an evolutionary biologist at Fred Hutchinson Cancer Research Center in Seattle.
“This makes the same situations that now spread – people who live in the same house, these types of internal, unventilated contacts – more likely to spread,” he said.