Stopping a comeback

Infections are declining and vaccines are being rolled out, but the biggest challenge is us, writes Apoorva Mandavilli

Across the the world, the coronavirus seems to be loosening its stranglehold. The deadly curve of cases, hospitalisations and deaths has yo-yoed before, but never has it plunged so steeply and so fast.

Is this it, then? Is this the beginning of the end? After a year of being pummeled by grim statistics and scolded for wanting human contact, many of us feel a longpromised deliverance is at hand.

The United States will win against the virus and regain many aspects of its prepandemic lives, most scientists now believe. Of the 21 interviewed for this article, all were optimistic that the worst of the pandemic is past. This northern hemisphere summer, they said, life may begin to seem normal again.

But — of course, there’s always a but — researchers are also worried that Americans, so close to the finish line, may once again underestimate the virus.

So far, the two vaccines authorised in the United States are spectacularly effective, and after a slow start, the vaccination rollout is picking up momentum. A third vaccine is likely to be authorised shortly, adding to the nation’s supply.

But it will be many weeks before vaccinations make a dent in the pandemic. And now the virus is shape-shifting faster than expected, evolving into variants that may partly sidestep the immune system.

The latest variant was discovered in New York City only this week, and another worrisome version is spreading at a rapid pace through California. Scientists say a contagious variant first discovered in Britain will become the dominant form of the virus in the United States by the end of March.

The road back to normalcy is potholed with unknowns: how well vaccines prevent further spread of the virus; whether emerging variants remain susceptible enough to the vaccines; and how quickly the world is immunised, so as to halt further evolution of the virus.

But the greatest ambiguity is human behaviour. Can Americans desperate for normalcy keep wearing masks and distancing themselves from family and friends? How much longer can communities keep businesses, offices and schools closed?

Covid-19 deaths will most likely never rise quite as precipitously as in the past, and the worst may be behind us. But if Americans let down their guard too soon — many states are already lifting restrictions — and if the variants spread in the United States as they have elsewhere, another spike in cases may well arrive in the coming weeks.

Scientists call it the fourth wave. The new variants mean “we’re essentially facing a pandemic within a pandemic”, said Adam Kucharski, a public health expert at the London School of Hygiene and Tropical Medicine.

The declines are real, but they disguise worrying trends.

The United States has now recorded

500,000 deaths amid the pandemic, a terrible milestone. As of Thursday, at least

28.3 million people have been infected. But the rate of new infections has tumbled by 35 per cent over the past two weeks, according to a database maintained by The New York Times. Hospitalisations are down 31 per cent, and deaths have fallen by 16 per cent.

Yet the numbers are still at the horrific highs of November, scientists noted. At least 3210 people died of Covid-19 in the US on Thursday alone. And there is no guarantee these rates will continue to decrease.

“Very, very high case numbers are not a good thing, even if the trend is downward,” said Marc Lipsitch, a researcher at the Harvard T.H. Chan School of Public Health in Boston. “Taking the first hint of a downward trend as a reason to reopen is how you get to even higher numbers.”

Parts of the country that experienced huge surges in infection, like Montana and Iowa, may be closer to herd immunity than other regions. But patchwork immunity alone cannot explain the declines throughout much of the world.

The vaccines were first rolled out to residents of nursing homes and to the elderly, who are at highest risk of severe illness and death. That may explain some of the current decline in hospitalisations and deaths.

But young people drive the spread of the virus, and most of them have not yet been inoculated. And the bulk of the world’s vaccine supply has been bought up by wealthy nations, which have amassed 1 billion more doses than needed to immunise their populations.

Vaccination cannot explain why cases are dropping even in countries where not a single soul has been immunised, like Honduras, Kazakhstan or Libya. The biggest contributor to the sharp decline in infections is something more mundane, scientists say: behavioral change.

Leaders in the United States and elsewhere stepped up community restrictions after the holiday peaks. But individual choices have also been important, said Lindsay Wiley, an expert in public health law and ethics at American University in Washington.

“People voluntarily change their behaviour as they see their local hospital get hit hard, as they hear about outbreaks in their area,” she said. “If that’s the reason that things are improving, then that’s something that can reverse pretty quickly, too.”

The downward curve of infections with the original coronavirus disguises an exponential rise in infections with B.1.1.7, the variant first identified in Britain, according to many researchers.

“We really are seeing two epidemic curves,” said Ashleigh Tuite, an infectious disease modeler at the University of Toronto.

The B.1.1.7 variant is thought to be more contagious and more deadly, and it is expected to become the predominant form of the virus in the US by late March. The number of cases with the variant in the US has risen from 76 in 12 states as of January 13 to more than 1800 in 45 states now. Actual infections may be much higher because of inadequate surveillance efforts in the US.

Buoyed by the shrinking rates over all, however, governors are lifting restrictions across the US and are under enormous pressure to reopen completely. Should that occur, B.1.1.7 and the other variants are likely to explode.

“Everybody is tired, and everybody wants things to open up again,” Tuite said. “Bending to political pressure right now, when things are really headed in the right direction, is going to end up costing us in the long term.”

Another wave may be coming, but it can be minimised. Looking ahead to late March or April, the majority of scientists interviewed by The Times predicted a fourth wave of infections. But they stressed that it is not an inevitable surge, if government officials and individuals maintain precautions for a few more weeks.

A minority of experts were more sanguine, saying they expected powerful vaccines and an expanding rollout to stop the virus. And a few took the middle road.

“We’re at that crossroads, where it could go well or it could go badly,” said Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.

The vaccines have proved to be more effective than anyone could have hoped, so far preventing serious illness and death in nearly all recipients. At present, about 1.4 million Americans are vaccinated each day. More than 45 million Americans have received at least one dose.

Yet the biggest unknown is human behavior, experts said. The sharp drop in cases now may lead to complacency about masks and distancing, and to a wholesale lifting of restrictions on indoor dining, sporting events and more. Or . . . not.

“The single biggest lesson I’ve learned during the pandemic is that epidemiological modelling struggles with prediction, because so much of it depends on human behavioural factors,” said Carl Bergstrom, a biologist at the University of Washington in Seattle.

Taking into account the counterbalancing rises in both vaccinations and variants, along with the high likelihood that people will stop taking precautions, a fourth wave is highly likely in the Northern Hemisphere’s spring, the majority of experts told The Times.

Kristian Andersen, a virus expert at the Scripps Research Institute in San Diego, said he was confident the number of cases will continue to decline, then plateau in about a month. After mid-March, the curve in new cases will swing upward again.

In early to mid-April, “we’re going to start seeing hospitalisations go up,” he said. “It’s just a question of how much.” Now the good news.

Despite the uncertainties, the experts predict that the last surge will subside in the United States sometime around June or July. If the Biden administration can keep its promise to immunise every American adult by the end of September, the variants should be no match for the vaccines.

Combine vaccination with natural immunity and the human tendency to head outdoors as weather warms, and “it may not be exactly herd immunity, but maybe it’s sufficient to prevent any large outbreaks”, said Youyang Gu, an independent data scientist, who created some of the most prescient models of the pandemic.

Infections will continue to drop. More important, hospitalisations and deaths will fall to negligible levels — enough, hopefully, to reopen the country.

“Sometimes people lose vision of the fact that vaccines prevent hospitalisation and death, which is really actually what most people care about,” said Stefan Baral, a researcher at the Johns Hopkins Bloomberg School of Public Health.

Even as the virus begins its swoon, people may still need to wear masks in public places and maintain social distance, because a significant percent of the population — including children — will not be immunised.

“Assuming that we keep a close eye on things in the summer and don’t go crazy, I think that we could look forward to a summer that is looking more normal, but hopefully in a way that is more carefully monitored than last summer,” said Emma Hodcroft, a molecular epidemiologist at the University of Bern in Switzerland.

Over the long term — say, a year from now, when all the adults and children in the United States who want a vaccine have received them — will this virus finally be behind us?

Every expert interviewed by The Times said no. Even after the vast majority of the American population has been immunised, the virus will continue to pop up in clusters, taking advantage of pockets of vulnerability. Years from now, the coronavirus may be an annoyance, circulating at low levels, causing modest colds.

Many scientists said their greatest worry post-pandemic was that new variants may turn out to be significantly less susceptible to the vaccines. Billions of people worldwide will remain unprotected, and each infection gives the virus new opportunities to mutate.

“We won’t have useless vaccines. We might have slightly less good vaccines than we have at the moment,” said Andrew Read, an evolutionary microbiologist at Penn State University. “That’s not the end of the world, because we have really good vaccines right now.”