It will take months before COVID-19 vaccines are widely available in the U.S. But massively scaling up testing, and quarantining people who test positive, could slow the spread of the virus now. A new study looks at the best ways that could happen.
“If we were to deploy this on a very large scale, we could dramatically slow the spread of the virus and save thousands of lives,” says Lauren Ancel Meyers, the director of the University of Texas COVID-19 Modeling Consortium and one of the authors of the study, published in Lancet Public Health.
In parts of the country where COVID-19 is spreading rapidly, the study suggests that it makes sense for every single person in the region—not just those who have symptoms—to get tested every week. People who are infected would then isolate for two weeks. In areas where transmission is lower, widespread testing could happen monthly, and people who were infected could stay home for one week. Even with the costs of all of the tests and lost wages, the societal costs would be far lower than letting the virus continue to spread.
The study modeled various scenarios, under the assumption that people would use $5 rapid antigen tests. While there’s still some uncertainty about exactly how accurate the tests are, they’re most accurate when people have the highest levels of virus—which is also when people are most likely to infect someone else, and the most crucial time to know whether someone has COVID-19.
Right now, most COVID-19 testing is happening in people who have symptoms, but to slow the spread of the virus, it’s critical to test everyone else. “When we wait for someone to have symptoms to test them and there’s a delay in getting results, and only at that point are we isolating them, we’re at a point where they’re almost done being infectious,” she says. “We’ve missed that early period prior to symptoms and during early symptoms when they’re probably most likely to be infecting other people. In addition, there’s a significant fraction of people who never develop symptoms at all. So if we are relying on symptoms to identify and isolate those people to protect their household members or their community members, then we’re letting those infections slip through.”
If a large percentage of Americans are vaccinated, it’s possible that we could reach herd immunity late in 2021. But it’s still unclear how quickly the shaky rollout of vaccine distribution will ramp up, how many people will choose to be vaccinated, and how well the vaccines protect against infections without symptoms. (Right now, it’s clear that the vaccines are very good at preventing symptomatic COVID-19, but it’s possible that some vaccinated people may be infected and still be able to infect others, which is one reason why anyone who gets the vaccine still needs to wear a mask for the moment.) It’s also not clear yet exactly how well the vaccines will protect against new variants of the virus, or if those new variants can infect people who’ve already had the original COVID-19. New lockdowns may slow the spread, or states may reopen too quickly.
“All of these things mean that we could approach herd immunity and see the virus start to subside within months, or we could be battling the virus for years,” says Meyers. “It’s just really uncertain. . . . We’ve made great strides in vaccination, and yet this virus continues to be elusive. So this is why ramping up testing is a really critical mitigation strategy for safeguarding the return to school, the return to workplaces, providing additional levels of protection if these variants turn out to be really challenging.”
The study found that it would be more cost-effective to test all Americans every month—with 12 million tests a day—than to continue with the status quo of only testing people with symptoms and their close contacts. The scientists estimated that testing in this low-transmission scenario would create more than $250 billion in net monetary benefits. Other experts, such as Michael Mina, an epidemiology professor at Harvard University, have been advocating massive testing for months. Some governments, such as that of Slovakia, have successfully run tests across their populations to help curb a surge in cases. While mass testing would be challenging to scale up in the U.S., Meyers says that it would also be helpful in smaller groups.
“Even if we can’t deploy it on this massive scale immediately where we’re truly testing everybody on a weekly or monthly basis, even deploying this in key places, like for children and teachers returning to schools, or in health settings, or our essential workforce—in places where we know there’s been a lot of transmission and there’s an ongoing risk—we could make a dramatic dent in the transmission of the virus and the numbers of hospitalizations and deaths in weeks and months to come,” she says.