Declining infection rates over all masked a rise in more contagious forms of the coronavirus. Vaccines will stop the spread, if Americans postpone celebration just a bit longer.
For weeks, the mood in much of the United States has been buoyant. Cases, hospitalizations and deaths from the coronavirus have fallen steeply from their highs, and millions of people are being newly vaccinated every day. Restaurants, shops and schools have reopened. Some states, like Texas and Florida, have abandoned precautions altogether.
In measurable ways, Americans are winning the war against the coronavirus. Powerful vaccines and an accelerating rollout all but guarantee an eventual return to normalcy — to backyard barbecues, summer camps and sleepovers.
But it is increasingly clear that the next few months will be painful. So-called variants are spreading, carrying mutations that make the coronavirus both more contagious and in some cases more deadly.
At the moment, most vaccines appear to be effective against the variants. But public health officials are deeply worried that future iterations of the virus may be more resistant to the immune response, requiring Americans to queue up for regular rounds of booster shots or even new vaccines.
“We don’t have evolution on our side,” said Devi Sridhar, a professor of public health at the University of Edinburgh in Scotland. “This pathogen seems to always be changing in a way that makes it harder for us to suppress.”
Until recently, B.1.1.7’s rise was camouflaged by falling rates of infection over all, lulling Americans into a false sense of security and leading to prematurely relaxed restrictions, researchers say.
“The best way to think about B.1.1.7 and other variants is to treat them as separate epidemics,” said Sebastian Funk, a professor of infectious disease dynamics at the London School of Hygiene and Tropical Medicine. “We’re really kind of obscuring the view by adding them all up to give an overall number of cases.”
Other variants identified in South Africa and Brazil, as well as some virus versions first seen in the United States, have been slower to spread. But they, too, are worrisome, because they contain a mutation that diminishes the vaccines’ effectiveness. Just this week, an outbreak of P.1, the variant that crushed Brazil, forced a shutdown of the Whistler Blackcomb ski resort in British Columbia.
Infections are rising again, driven to an uncertain degree by B.1.1.7 and other variants. Earlier this week, Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, pleaded with Americans to continue to practice masking and social distancing, saying she felt a sense of “impending doom.”
“We have so much to look forward to — so much promise and potential of where we are and so much reason for hope,” she said. “But right now I’m scared.”
The coronavirus was supposed to be slow to change shape. Like all viruses, it would pick up mutations and evolve into thousands of variants, scientists said at the beginning of the pandemic. But it would not change significantly for years — a stupid virus, some called it.
The pathogen defied those predictions. “We expected the virus to change,” said Dr. Michael Diamond, a viral immunologist at Washington University in St. Louis. “We didn’t quite anticipate how quickly it was going to occur.”
A variant is of concern only if it is more contagious, causes more severe disease, or blunts the immune response. The variants identified in Britain, South Africa, Brazil and California all fit the criteria.
So contagious is B.1.1.7 that Britain succeeded in driving down infections only after nearly three months of strict stay-at-home orders, plus an aggressive vaccination program. Even so, cases fell much more slowly than they did during a similar lockdown in March and April.
In continental Europe, a wave of B.1.1.7 cases was building for months, mostly unnoticed beneath a steady churn of infections. The variant wave is now cresting.
Poland’s rate of daily new cases has quintupled since mid-February, forcing the closure of most public venues. Germany’s has doubled, triggering a ban on nighttime gatherings in Berlin.
For too long, government officials disregarded the threat. “Case plateaus can hide the emergence of new variants,” said Carl Pearson, a research fellow at the London School of Hygiene and Tropical Medicine. “And the higher those plateaus are, the worse the problem is.”
Even when cases were falling, researchers questioned the notion that vaccinations were the reason. Millions of Americans are immunized every day, but even now only 31 percent have received a single dose of a vaccine, and just 17 percent of the population have full protection, leaving a vast majority susceptible.
“The fact is that we’re still in a position now where we don’t have enough vaccinated people,” said Kristian Andersen, a virologist at the Scripps Research in San Diego. “And if we, like Texas, say we’re done with Covid-19, B.1.1.7 will come in and remind us that we are not right. I have no doubt about it.”
The variant is particularly pervasive in Florida, where the state lifted restrictions and initially did not see a surge. Officials in other states cited this as a rationale for reopening. But now Florida’s infection rate is curving upward.
The variant may only have been obscured by what scientists like to call seasonality. Respiratory infections are usually rare in Florida in the spring, noted Sarah Cobey, an evolutionary biologist at the University of Chicago. Coronavirus infections peaked in Florida last year in the summer, as heat drove people indoors, and may do so again.
“I still don’t think we’re out of the woods,” Dr. Cobey said, referring to the country at large. “If we don’t have another wave this spring, then I’m going to be really, really worried about the fall.”
While most vaccines are effective against B.1.1.7, researchers are increasingly concerned about other variants that contain a mutation called E484K. (Scientists often refer to it, appropriately, as “Eek.”)
This mutation has evolved independently in many variants worldwide, suggesting that it offers the virus a powerful survival advantage.
“I think for the next year or two, E484K will be the most concerning” mutation, said Jesse Bloom, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle.
The mutation slightly alters the so-called spike protein sitting on the surface of the coronavirus, making it just a bit harder for antibodies to latch on and destroy the invader.
The good news is that the virus seems to have just a few survival tricks in its bag, and that makes it easier for scientists to find and block those defenses. “I’m feeling pretty good about the fact that there aren’t that many choices,” said Michel Nussenzweig, an immunologist at Rockefeller University in New York.
The Eek mutation seems to be the virus’s primary defense against the immune system. Researchers in South Africa recently reported that a new vaccine directed against B.1.351 ought to fend off all other variants, as well.
Pfizer, BioNTech and Moderna already are testing newly designed booster shots against B.1.351 that should work against any variants known to blunt the immune response.
Instead of a new vaccine against variants, however, it may be just as effective for Americans to receive a third dose of the Pfizer-BioNtech or Moderna vaccines in six months to a year, said Dr. Anthony S. Fauci, head of the National Institute of Allergy and Infectious Diseases.
That would keep antibody levels high in each recipient, overwhelming any variant — a more practical strategy than making a specialized vaccine for each new variant that emerges, he said.
“My only concern about chasing all the variants is that you’d almost be playing Whac-A-Mole, you know, because they’ll keep coming up and keep coming up,” Dr. Fauci said.
In one form or another, the new coronavirus is here to stay, many scientists believe. Multiple variants may be circulating in the country at the same time, as is the case for common cold coronaviruses and influenza. Keeping them at bay may require an annual shot, like the flu vaccine.
The best way to deter the emergence of dangerous variants is to keep cases down now and to immunize the vast majority of the world — not just the United States — as quickly as possible. If significant pockets of the globe remain unprotected, the virus will continue to evolve in dangerous new ways.
“This might be something that we have to deal with for a long time,” said Rosalind Eggo, an epidemiologist at London School of Hygiene and Tropical Medicine.
Still, she added, “Even if it changes again, which it is very likely to do, we are in a better, much stronger position than a year ago to deal with it.”
Category: Science
Source: New York Times
