The Delta variant now causes about a third of new Covid-19 cases in New England. Researchers estimate it is twice as transmissible as the original coronavirus, but are uncertain whether it makes people sicker than other Covid-19 strains.
To date, only five Delta variant cases have been identified in Vermont, which public health experts credit to the state’s high vaccination rate.
“The data shows that all three vaccines work against the variants circulating in the U.S., so if you want to protect yourself against Covid and its variants, the best way to do that is to get vaccinated,” Dr. Mark Levine, the state health commissioner, told Vermonters at a press conference Tuesday.
Unvaccinated people and people who have received only one dose of either the Moderna or Pfizer vaccines are at higher risk of infection from the Delta variant, according to Dr. Timothy Lahey, an infectious disease specialist at UVM Medical Center. The partial protection gained by the first dose in a two-part vaccine is less effective against Delta than the original Covid virus.
Levine said there is no evidence to suggest vaccinated people need booster shots, no matter which of the three vaccines they received. The CDC and the FDA said the same in a joint statement July 8.
The duration of vaccine protection “seems to be quite good,” Levine said. “But there’s still a lot of investigation going on regarding the immune response, which is a good thing.”
Israel began administering third doses of the Pfizer vaccine Monday to immunocompromised people. The same day, according to a New York Times report, Pfizer executives met with top U.S. government scientists to push for authorization of a booster vaccine.
“That’s probably driven by corporate interests much more than epidemiological ones,” said Anne Sosin, a policy fellow at the Nelson A. Rockefeller Center at Dartmouth College.
If someone came to a vaccine site in Vermont asking for a Covid-19 booster, they would probably be denied, Levine said, as there’s no evidence to show a booster is necessary.
Public health departments determine a variant’s prevalence by conducting genomic sequencing on a small sample of Covid tests. Genomic sequencing isn’t universal because the genetic makeup of any particular Covid infection doesn’t change the recommended treatment.
“That’s not done every time because that’s a very laborious study,” said Lahey at UVM. “It’s kind of like how you could just recognize with your eyes like that is a tiger, or that is a cheetah. But if you wanted to know, ‘Is that a tiger from a particular family?’ it would take a lot more work to figure out.”
Levine said a higher percentage of Vermont’s positive Covid-19 tests are sequenced because there are few new infections in the state.
This week, an additional 2,400 Vermonters received their first vaccine dose, bringing the state’s vaccination rate up to 82.8%.
There were 47 new cases reported in Vermont this week, an uptick from the previous week, but still very low compared to the pandemic’s peak. In the same period, infections across the Northeast increased by 38%. The state projects the infection rate among unvaccinated people will continue to trend upward.
“Delta’s impact can be seen in even the most vaccinated region in the country,” said Michael S. Pieciak, commissioner of the Vermont Department of Financial Regulation.
Sosin is concerned how the Delta variant might affect students this fall, as vaccines remain unapproved for children under 12.
Kids have generally been pretty safe from infections at school “because we have a lot of controls in place to prevent that from happening,” Sosin said. “Remove those controls, and then introduce a more transmissible virus, and we can expect lots of kids to get impacted.”
Vermont Secretary of Education Dan French said health guidelines for schools are forthcoming in August.
“We're still thinking that if any mitigation steps are necessary in schools, they'll be fairly nominal and easy to follow,” French said.
Correction: Tim Lahey's name was misspelled in an earlier version of this story.