The news that the coronavirus vaccine may stop transmission of the virus is leading to greater optimism among experts that the United States may return to normal sooner.
Two new studies from Israel are the first to show that the vaccines may actually stop the virus from traveling from one person to another. The first study, from Chaim Sheba Medical Centre, found that the Pfizer vaccine was 75% effective at preventing both symptomatic and asymptomatic cases of COVID-19 at 15 to 28 days after the first dose. The second study, by Pfizer and the Israeli Health Ministry, showed that the vaccine had 89% efficacy at preventing infections.
If vaccines actually stop infection then there will be less need for mitigation measures such as masks and social distancing as the vaccination program proceeds.
“I think those studies support what we thought would happen,” said Nicole Baumgarth, a professor at the Center for Immunology and Infectious Diseases at the University of California Davis. “It’s great news.”
Baumgarth said that the U.S. might return to normal around Thanksgiving, with people able to gather at home to enjoy the holiday season. But, like most experts, Baumgarth is cautiously optimistic, warning that getting to normalcy will depend on a sufficient number of people getting vaccinated.
Mark Slifka, a professor of microbiology and immunology at Oregon Health and Science University, wouldn’t say specifically when the U.S. would return to normal but did say that the U.S. will get there quickly if the vaccines do prevent infection.
“I guess you could use the phrase ‘compound interest,’” Slifka said. “If we can prevent the disease in a person who’s been vaccinated, that’s a plus. But if we can also reduce their transmission of the disease to others, that’s compound interest. It adds up really quickly because the cases will go down really quickly under those circumstances.”
The seven-day average of new cases in the U.S. is currently just under 66,000. That is a 78% drop since the peak in cases in early January.
“I think there will be spectrums of normal,” said Susan Hassig, an epidemiology professor at Tulane University School of Public Health and Tropical Medicine.
Hassig said that if more vaccines like the one from Johnson & Johnson become available, restrictions such as restaurant capacity would be eased. However, mask-wearing may continue for a while.
“I suspect a blanket ‘no need to wear masks’ will be one of the last things to happen,” she said.
Most experts say that we need more research before we can be more confident that the vaccines do prevent infection.
“We have to be very careful with the [two Israeli studies],” said Susanne Straif-Bourgeois, a professor of epidemiology at the LSU Health Sciences Center. “There are a lot of other factors that could have an impact on their results that they can’t control in those studies.”
She noted that other factors such as mask-wearing and lockdowns and seasonal factors such as warmer weather might also have an affect on the low levels of infection in the Israeli studies.