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The lingering threat of fall Covid-19 outbreaks

The vaccines are holding Covid-19 down in the US for now, but it could come back this fall.

A discarded face mask and fallen autumn leaves in Berlin on November 6, 2020.
David Gannon/AFP via Getty Images

You’ve heard it before, but it’s true: This summer in America is going to be so good. After a year of Covid-19-induced fear, the US vaccination campaign and warmer weather will give the country a much-needed reprieve from the coronavirus and all the horrors it brought.

But what comes after the summer?

Last year, we saw that the coronavirus spreads more easily in the fall and winter than it does in warmer months. More than 330,000 Americans died from Covid-19 over six months during the fall and winter — an unimaginable death toll, amounting to nearly nine times all car crash deaths in 2019 and more than 17 times all murders.

One cause was the country’s relaxed response to the coronavirus, as much of America dropped its guard and precautions. But experts also blame the seasonality of Covid-19, as falling temperatures pushed people indoors, where the virus has an easier time spreading, and families gathered for the holiday season.

America is in a much better place than it was last fall and winter. A combination of the vaccines and natural immunity from past Covid-19 infections is suppressing the virus. But the country isn’t totally in the clear yet: The majority of the US population still isn’t vaccinated, and the rate of daily vaccinations has dramatically slowed, now standing at about half of what it was at its peak in mid-April.

Then there are the coronavirus variants. The vaccines do a good job overpowering the known variants, based on the research, but at least some variants do seem to overcome some natural immunity. So people in the US who are unvaccinated but have had Covid-19 before might still be vulnerable. Some experts also worry that natural immunity from a previous infection might not be durable — perhaps fading over time, potentially in time for a fall wave. (There are similar concerns about the vaccines, but vaccine-induced immunity so far has proven to be better than natural immunity in research trials.)

There’s a risk, too, that the warmer weather and potential seasonality of the virus will in some sense give the country a false sense of security. By letting much of the US (though not all) safely socialize outside, while Covid-19 cases and deaths continue to decline, there’s a risk that people will move on from the virus too quickly — and the remaining unvaccinated will come to believe, if they don’t already, that they don’t really need to get the shot.

All of these factors — the holidays, colder weather, variants, and at least some immunity potentially dropping off — could combine to create a Covid-19 comeback this fall and winter. The experts I’ve talked to don’t believe this will be a huge, nationwide surge — too many will be vaccinated by the fall for that to happen. But particularly in parts of the country with low vaccination rates, there could be local or state-level spikes of the coronavirus.

“It could happen — if we really stall in our vaccination coverage,” Jen Kates, director of global health and HIV policy at the Kaiser Family Foundation, told me. “If we increase our vaccination coverage, I’m less worried about that.”

This isn’t a reason to despair. Especially if you’re vaccinated, you’re extremely safe from Covid-19. Rather, this is a call for more people to get vaccinated — it’s the one way the country can guarantee another fall or winter surge never comes.

We’re still not done with the pandemic

The news on Covid-19 in the US is genuinely incredible right now. Almost half the country has had at least one vaccine dose. Daily new coronavirus cases are less than a 10th of what they were during a January peak, and deaths are down more than 85 percent from January as well. The higher vaccination rates, decline in cases and deaths, and warmer weather will soon, if they haven’t already, let us safely engage in the kinds of social interactions that were dangerous just a year ago.

This is all genuinely fantastic, thrilling news. Personally, I’m planning trips and vacations that I would have been too scared to do a year ago. I no longer wear a mask unless it’s required by law or by the businesses I’m patronizing. I’ll very soon see friends and family that I haven’t seen in a long time. As someone who’s vaccinated, I just don’t worry about my own risk of Covid-19 at all anymore — and many experts share that view as well.

But this optimism can be taken a bit too far. As much as things have improved, they’re not completely back to normal yet. Covid-19 cases and deaths are still near or above levels that were considered fairly high last summer. More than 60 percent of the country still isn’t fully vaccinated, and more than half haven’t gotten at least one shot. In some states, rates of vaccination are even lower — with two-thirds of the population not getting one shot yet.

“It’s good to celebrate at this stage,” Mauricio Santillana, a researcher at Harvard Medical School and Boston Children’s Hospital, told me. “But we cannot be fully confident that this is the end of it.”

That large unvaccinated population means a lot of people remain vulnerable to the virus. We don’t know what level of vaccination is needed for herd immunity (the level of immunity that ensures infections won’t spread within a community), but experts believe it will require at least 60 percent of the population vaccinated and perhaps as high as 85 or 90 percent, depending in part on the variants we’re dealing with.

The remaining vulnerabilities could grow, too. Natural immunity could fade over time, or more infectious variants could pop up. As fall arrives and the weather cools, people will shift activities back to poorly ventilated indoor environments where airborne viruses can more easily spread. People could drop their guard too much, especially if Covid-19 cases continue to decline over the summer.

“I do think in the fall and winter, things will be much better,” Ashish Jha, dean of the Brown University School of Public Health, told me. “But we may very well see a bump, and we may need to put in some mild public health restrictions for short periods of time if we see surges in cases.” He added, “We have to be ready.”

Imagine a potential scenario: Cases and deaths continue to drop. The summer brings a renewal of social activities. Covid-19 starts to look like a thing of the past. Covid-related precautions, legal and voluntary, are widely discarded. In this environment, people who have yet to get the vaccine decide maybe they don’t need to — after all, the virus isn’t really a present threat anymore. So cases and deaths drop, but so do vaccination rates.

Then the fall comes. More people move indoors, travel, and gather for the holidays. Maybe a new variant becomes the dominant form of the virus in the US. At the same time, perhaps natural immunity is weakened. In a few parts of the country, such as the South and Midwest, a lot of the population remains unvaccinated. Suddenly, the virus starts to pick up locally, or maybe even beyond that, especially if vaccination rates are low statewide. Local and state governments may be slow to react, resistant to reinstituting restrictions they had only recently celebrated the end of.

This scenario isn’t guaranteed. Maybe the vaccines are so great that it turns out America’s current vaccination rates, along with natural immunity that perhaps turns out more durable than previously thought, is enough to keep the coronavirus at bay.

But it’s a risk. And it’s an unnecessary one given that there is a good way to avoid it.

There’s a solution: Vaccinate more people

The vaccines are great. Evidence from clinical trials and the real world has found that they nearly eliminate the risk of serious illness, hospitalization, and death from Covid-19. In Israel, which has the world’s most advanced vaccination campaign, a vaccination rate of 60 percent has let the country remain nearly fully open and see daily Covid-19 deaths fall to the single digits or zero — a big improvement for a country that experienced some of the worst coronavirus surges in the world.

But the vaccines can only do their thing if more people get vaccinated. America is not at Israel’s 60 percent rate. And there’s a good chance the US will have to go higher than that — given that Israel’s reopening still involves mask mandates and vaccine passports, both of which Americans are increasingly rejecting.

As long as there are “pockets of people who choose not to vaccinate, you leave the door open for Covid to come back,” Santillana said. “We need to stay vigilant.”

For lawmakers and other leaders, that means doing more work to get people vaccinated. Experts have called for a three-tiered approach: improving access, providing incentives, and imposing some mandates if necessary. That could mean, at the state level, partnering with entertainment and transportation venues to offer shots on-site, providing financial or other material rewards to the vaccinated, and pushing schools, including colleges, to require vaccinations. It could also mean, on the private side, employers offering vaccines on-site, handing out pay bonuses to the vaccinated, and making vaccination required to come back to the office.

For the public, that means more people choosing to get vaccinated. One thing that could help here is vaccinated people sharing their stories, given that almost one in five people is in wait-and-see mode with the vaccines, largely standing by until the people around them get the shot.

America just got through a pandemic year with so much uncertainty. It has a chance to stamp out one of the last bits of uncertainty — and the risk of another fall and winter surge — if as many people as possible get vaccinated. But it’s on everyone to make that happen.

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