How to combat delta, according to Harvard epidemiologist

Officials at the Centers for Disease Control and Prevention (CDC) are warning that “the war has changed” with the surge of the highly contagious delta variant. The New York Times reports that new cases in the U.S. have soared 139 percent in the past two weeks, and the CDC estimates that more than 82 percent of those are delta variant. Public health officials believe the strain — which appears to cause more serious illness than earlier variants — is now the predominant one in the nation.

William Hanage, associate professor of epidemiology at the Harvard T.H. Chan School for Public Health, offered a few pieces of advice on prevention during a Q&A on the variant hosted jointly by the Chan School and GBH’s “The World” on Tuesday.

Get vaccinated

The delta variant moves swiftly, so it is vital to be vaccinated against exposure, Hanage said.

“It’s reasonable to suggest that before terribly long, everyone in the country will either have been infected with delta or vaccinated,” he said.

The greater the proportion of the population vaccinated, the better, he said. The vaccines’ efficacy against severe or lethal infection will likely prevent the overload on the health care system that the Alpha variant caused last spring.

Redoubling efforts to get people vaccinated as soon as possible can prevent the worst of the surge, Hanage said, but in areas with low rates of vaccination, delta can be “nothing short of catastrophic.”

“We’re here with delta because the pandemic is a very long-term event, and it’s going to be with us for some time. But we’re in a much better position because we have vaccines,” he added. “The vaccine is the single best thing anyone can do to protect themselves and others.”

Mask up

The CDC has resumed its guidance for masking indoors, especially in areas with low vaccination and higher transmission. Even for people who are already vaccinated, masking offers another layer of protection, Hanage said.

Outdoor transmission remains relatively low, but wearing masks in large crowds — or avoiding them altogether — can provide more protection, especially for the unvaccinated.

“Even though we have vaccines, all these other weapons in our arsenal have not become useless,” Hanage said. “Masks are a pretty light lift.”

Socialize responsibly

We might not need to return to our insular social bubbles, but taking appropriate precautions is still beneficial. Vaccinated people interacting with other vaccinated people are likely relatively safe from infection, but activities such as eating indoors at restaurants or attending large events like sports games or concerts could still put people at risk of the delta variant.

“Because you’re vaccinated, you could be feeling overly confident and making contacts you wouldn’t have otherwise,” Hanage said. “Think about contacts who are unvaccinated, or immunocompromised people. Those are the ones for whom the delta surge will be a risk.”