Within a few weeks, two variants of the coronavirus became so well-known that you often hear their unfathomable alphanumeric names pronounced on television news.
B.1.1.7, first identified in Britain, showed the power to spread rapidly and rapidly. In South Africa, a mutant called B.1.351 can evade human antibodies and blunt the effectiveness of some vaccines.
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Scientists also mentioned a third about the variant that originated in Brazil, P.1. Research has been slower on P.1 since it was discovered at the end of December, and scientists are uncertain how much to worry about.
“I held my breath,” said Bronwyn MacInnis, a public health researcher at the Broad Institute.
Three studies now provide a sobering history of the meteoric rise of P.1 in the Amazon city of Manaus. It probably originated there in November and then fueled a record increase in cases of coronavirus. The research found that it was partly predominant due to an increased infectivity.
But it also gained the ability to infect some people who had immunity to the previous attacks of COVID-19. And laboratory experiments suggest that P.1 may weaken the protective effect of a Chinese vaccine now used in Brazil.
The new studies have yet to be published in scientific journals. Their authors warn that findings about cells in laboratories do not always translate into the real world, and that they have only begun to understand P.1’s behavior.
“The findings apply to Manaus, but I do not know if they apply elsewhere,” said Nuno Faria, a virus expert at Imperial College London, who helped lead much of the new research.
But even with the riddles remaining around P.1, experts have said it is a variant to take seriously. “It’s right to worry about P.1, and these data give us the reason why,” said William Hanage, a public health researcher at the Harvard TH Chan School of Public Health.
P.1 now spreads over the rest of Brazil and is found in 24 other countries. In the United States, the Centers for Disease Control and Prevention reported six cases in five states: Alaska, Florida, Maryland, Minnesota, and Oklahoma.
To reduce the risks of P.1 outbreaks and re-infections, Faria said it was important to double each measure to slow the spread of the coronavirus. Masks and social distance can work at P.1. And vaccination can help reduce its transmission and protect those who become infected from serious diseases.
“The ultimate message is that you need to increase all vaccination efforts as quickly as possible,” he said. “You have to be one step ahead of the virus.”
Faria and his colleagues began detecting the coronavirus when it exploded in Brazil last year. Manaus, a city of 2 million in the Brazilian Amazon, was particularly hard hit. During his spring, Manaus’ cemeteries were overwhelmed by the corpses of the dead.
But after a peak at the end of April, Manaus seemed to have overcome the worst pandemic. Some scientists thought that the decline meant that Manaus gained herd immunity.
Faria and his colleagues searched for coronavirus antibodies in samples from a Manaus blood bank in June and October. They found that about three-quarters of the inhabitants of Manaus were infected.
But by the end of 2020, new business began to increase again. “There were actually a lot more cases than in the previous peak of cases, which was the end of April,” Faria said. “And it was very mysterious to us.”
Faria and his colleagues asked themselves whether new variants could be partly to blame for the revival. In Britain, researchers have found that B.1.1.7 is rising across the country.
In search of variants, Faria and his colleagues began a new attempt at genome sequencing in the city. While B.1.1.7 arrived in other parts of Brazil, they did not find it in Manaus. Instead, they found a variant that no one had seen before.
Many variants in their samples shared a set of 21 mutations not seen in other viruses circulating in Brazil. Faria texted a colleague: “I think I’m looking at something really weird, and I’m quite worried about it.”
Some mutations in particular worried him, because scientists had already found them in B.1.1.7 or B.1.351. Experiments have suggested that some of the mutations would better enable the variants to infect cells. With other mutations, they can evade antibodies from previous infections or through vaccines.
While Faria and his colleagues were analyzing their results, researchers in Japan made a similar discovery. Four tourists who returned on January 4 from a trip to the Amazon were positive for the coronavirus. Genome sequencing revealed the same set of mutations that Faria and his colleagues saw in Brazil.
On January 12, Faria and his colleagues posted a description of P.1 on an online forology forum. They then investigated why P.1 was so common. Its mutations may have made it more contagious, or it was lucky. With a mere chance, the variant would possibly have appeared in Manaus, just as the city becomes more relaxed about public health measures.
It was also possible that P.1 became common because it could re-infect humans. Normally, coronavirus re-infections are rare because the antibodies that the body produces after infection are strong for months. But it was possible that P.1 had mutations that could make the antibodies harder on it, allowing it to slip into cells and cause new infections.
The researchers tested these possibilities by detecting P.1 from the earliest samples in December. At the beginning of January it was 87% of the samples. By February, it had completely taken over.
By combining the data of genomes, antibodies and medical records in Manaus, the researchers concluded that P.1 conquered the city, not thanks to luck, but also through biology: the mutations helped spread it. Like B.1.1.7, it can infect more people on average than other variants can do. They estimate that it is somewhere between 1.4 and 2.2 times more transmissible than other lines of coronaviruses.
But it also gets a lead of mutations that cause the antibodies of other coronaviruses to escape. They estimate that in 100 people infected with non-P.1 lines in Manaus last year, somewhere between 25 and 61 of them could have been infected again if they had been exposed to P.1 in Manaus.
The researchers found support for this conclusion in an experiment in which they mixed P.1 viruses with antibodies from Brazilians who had COVID-19 last year. They found that the effectiveness of their antibodies decreased sixfold compared to P.1 compared to other coronaviruses. That drop could mean that at least some people would be vulnerable to new infections from P.1.
“There seems to be an increasing body of evidence suggesting that most cases related to the second wave are indeed types of reinfections,” Faria said.
Faria and other researchers are now looking at Brazil to observe the distribution of P.1. Dr. Ester Sabino, an expert on infectious diseases at the University of São Paulo School of Medicine, said that one of the new outbreaks in Araraquara, a Brazilian city with 223,000 people, has arisen that is not COVID-19 before P .1 had not. arrived.
If people in Araraquara did not have a high level of antibodies before the arrival of P.1, she said, it suggests that the variant could possibly spread to places without the extreme history of Manaus. “It can happen anywhere else,” she said.
Michael Worobey, a virus expert at the University of Arizona who was not involved in the research, said it was time to pay attention to P.1 in the United States. He expected it to become more common in the United States, although it would have to compete with B.1.1.7, which would soon become the predominant variant in much of the country.
“At least it’s going to be one of the candidates,” Worobey said.
In their experiments, Faria and his colleagues also tested antibodies from eight people who received CoronaVac, a Chinese vaccine used in Brazil. They found that the vaccine-generated antibody bodies were less effective at stopping the P.1 variant than other species.
Faria warned that these results, derived from cells in test tubes, do not necessarily mean that vaccines will be less effective at protecting real people from P.1. Vaccines can protect very well against P.1, even if the antibodies they generate are not as strong. And even if the variant succeeds in infecting vaccines, they are likely to be protected from a severe attack on COVID-19.
For Sabino, the utmost importance of P.1 is the threat that variants pose when they can emerge anywhere in the world.
“It’s just a matter of time and chance,” she said.
This article originally appeared in The New York Times.
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