The Brazilian virus variant has infected many who have already recovered from Covid-19

In just a few weeks, the two versions of the coronavirus became so familiar that you could hear their alphanumeric names regularly unspoken in television news.

B.1.1.7, first identified in Britain, showed its ability to spread rapidly and rapidly. In South Africa, a mutant called B.1.351 can avoid human antibodies by dampening the effectiveness of some vaccines.

Scientists also looked at the third part of a variant called P.1 that arose in Brazil. The end of P1 research has been slower since its discovery in late December, so scientists were unsure how much they would have to worry about.

“I held my breath,” said Bronwyn MacInnis, an epidemiologist at the Broad Institute.

Now, three studies offer a sobering story of the meteoric rise of P.1 in the Amazon city of Manaus. It probably occurred there in November and then fueled a record-breaking fire of coronavirus cases. This research dominated the city in part because of the increased infection, the research revealed. But he was also able to infect some people who had immunity to previous seizures of Covid-19. And laboratory experiments suggest that P.1 may weaken the protective effect of a Chinese vaccine currently used in Brazil.

The new studies have not yet been published in scientific journals. Their authors caution that findings about laboratory cells are not always realized and have only begun to understand the behavior of P.1.

“The findings apply to Manaus, but I don’t know if they apply to other places,” said Nuno Faria, a virologist at Imperial College London who helped lead much of the new research.

But despite the mysteries left around P.1, experts say it’s a version that needs to be taken seriously. “It’s right that we’re worried about P.1, and these data give us the reason,” said William Hanage, an epidemiologist at Harvard’s TH Chan School of Public Health.

P.1 is currently prevalent in the rest of Brazil and is found in another 24 countries. In the United States, Centers for Disease Prevention and Control registered six cases in five states: Alaska, Florida, Maryland, Minnesota, and Oklahoma.

In order to reduce the risk of P.1 epidemics and re-infections, Dr. Faria said it is important to double all measures to slow down the spread of the coronavirus. Masks and social distance act against P.1. And vaccination can help spread it and protect those who become infected with serious diseases.

“The final message is that you need to step up all vaccination efforts as soon as possible,” he said. – You need to be one step ahead of the virus.

Dr. Faria and colleagues began tracking the coronavirus when it exploded in Brazil last spring. The Brazilian Amazon city of 2 million, Manaus, was hit particularly hard. At its spring peak, Manaus cemeteries were flooded with bodies of the dead.

But after the peak in late April, Manaus seemed to have gotten over the worst situation of the pandemic. According to some scientists, the drop meant that Manaus gained the immunity of the herd.

Dr. Faria and colleagues searched for coronavirus antibodies in samples from a manausal blood bank in June and October. Roughly three-quarters of Manaus residents were found to be infected.

But near the end of 2020, new cases began to jump. “In fact, there were a lot more cases than at the previous peak, which was in late April,” Dr. Faria said. “And that was very thought-provoking for us.”

To find variants, Dr. Faria and colleagues launched new genome sequencing efforts in the city. While B.1.1.7 arrived in other parts of Brazil, it was not found in Manaus. Instead, they found a version that no one had seen before.

Many of the variants in their samples consist of 21 mutations that are not seen in other viruses circulating in Brazil. Dr. Faria sent a text message to a colleague: “I think I’m looking at something really weird and I’m very worried about that.”

Some mutations were of particular concern because scientists had already found them in B.1.1.7 or B.1.351. The experiments suggested that some mutations were better able to infect the variants with the cells. Other mutations allow the avoidance of antibodies from previous infections or produced by vaccines.

While Dr. Faria and colleagues analyzed their findings, Japanese researchers made a similar discovery. Four tourists who returned home from a trip to the Amazon on January 4 showed a positive result for the coronavirus. Genome sequencing revealed the same mutations that Dr. Faria and colleagues saw in Brazil.

Dr. Faria and colleagues posted a P.1 description at an online virology forum on January 12th. It was then examined why P.1 was so common. Its mutations could have made it more contagious or it could have been lucky. Mere coincidentally, the version may have appeared in Manaus when the city became milder due to public health measures.

It was also possible that P.1 became common because it could re-infect humans. Normally, re-infection with the coronavirus is rare because the antibodies produced by the body after the infection are effective for months. But it was possible that P.1 carried mutations that made it difficult to bind these antibodies, allowing it to slide into cells and develop new infections.

The researchers tested these possibilities by following the earliest samples of P.1 in December. By early January, it accounted for 87 percent of the samples. He took full power by February.

Combining data from Manaus genomes, antibodies, and medical documents, the researchers concluded that P.1 had conquered the city not because of luck but because of its biology: its mutations facilitated its spread. Like B.1.1.7, it can infect more people on average than other variants. They estimate that it spreads somewhere between 1.4 and 2.2 times better than other lines of coronaviruses.

But it also benefits from mutations that allow it to avoid antibodies to other coronaviruses. They estimate that in 100 people who became infected in Manaus last year, somewhere between 25 and 61 were infected with P.1.

The researchers supported this conclusion in an experiment in which P.1 viruses were mixed with antibodies from Brazilians who received Covid-19 last year. They found that their antibodies were six times more effective against P.1 compared to other coronaviruses. This decrease could mean that at least some people would be vulnerable to new infections from P.1.

“There seems to be growing evidence to suggest that the majority of cases associated with the second wave are indeed a form of re-infection,” Dr. Faria said.

Dr. Faria and other researchers are now looking for the spread of P.1 in Brazil. Dr. Ester Sabino, an infectious disease expert at the University of São Paulo School of Medicine, said one of the new outbreaks occurred in Araraquara, a Brazilian city of 223,000, where the rate of Covid-19 was not high before the arrival of P.1.

If the people of Araraquara did not have high antibody levels before the arrival of P.1, it is said that this suggests that the variant may spread in places without an extreme history of Manaus. “It could happen anywhere else,” he said.

Michael Worobey, a virologist at the University of Arizona who did not participate in the research, said it was time to pay attention to P.1 in the United States. He expected this to become more common in the United States, although he would have to compete with B.1.1.7, which could soon become the dominant variant in much of the nation.

“At least this will be one of the competitors,” Dr. Worobey said.

In his experiments, Dr. Faria and colleagues also tested antibodies to eight people who received the Chinese-made CoronaVac vaccine used in Brazil. The antibodies generated by the vaccine were found to be less effective in stopping variant P.1 than other types.

Dr. Faria warned that these results from cells in test tubes do not necessarily mean that vaccines are less effective in protecting real people from P.1. Vaccines may very well provide strong protection against P.1, even if the antibodies they produce are not as effective. And even if the variant manages to infect vaccinated people, they are likely to remain protected from a severe attack of Covid-19.

For Dr. Sabino, the ultimate importance of P.1 is the danger that the variants pose when they can pop up anywhere in the world.

“It’s just a matter of time and chance,” she said.