Do high-vaccination towns need mask mandates?

Aimee Krauss, the director of the West Hartford-Bloomfield Health District, is responsible for two towns with some of the highest vaccination rates in the state. But when cases started climbing in July and August, both towns decided to implement mask mandates.

“Both West Hartford and Bloomfield do have a good vaccination rate. We are pushing to make it a better rate,” Krauss said. Nevertheless, masking is “the best mitigation measure we have regarding this virus.”

The Centers for Disease Control and Prevention updated guidance regarding indoor masking on July 28, recommending that vaccinated individuals wear masks in specific settings. Currently, all counties in Connecticut meet the CDC’s transmission criteria for indoor masking.

Earlier this month, Gov. Ned Lamont decided not to enact a statewide mask mandate. Instead, he allowed each of Connecticut’s 169 towns and cities to enact their own mask mandates, citing differential vaccination coverage across the state as a key reason why more localized rules were necessary.

But a CT Mirror analysis of the most recent state data from last week showed that higher vaccination rates do not necessarily correspond with lower rates of new cases on the town level, suggesting that the two are somewhat independent. The weak correlation raises the question of how strongly vaccination rates should be factored into decisions regarding other disease mitigation strategies like masking.

The governor’s policy has also received some pushback from local leaders who argue that the approach is less effective and confusing, but it’s one that Connecticut is committed to for the time being.

“The governor’s current approach, from a policy perspective, is what we’re trying to stick with for now, given that we have seen a flattening of the key metrics,” said Josh Geballe, the state’s chief operating officer.

Twenty-five towns have imposed some form of mask mandate so far, according to The Hartford Courant.

The Connecticut Department of Public Health did not respond to written questions.

Vaccination rates are “a reasonable starting point” in thinking through that decision, said Saad Omer, epidemiologist at the Yale School of Public Health. “But at a mayor level, I would be looking at your case trajectory.”

Two things can be true at once: COVID vaccines are effective at reducing the risk of symptomatic disease, severe illness and death, even against the highly contagious delta variant that is currently dominant in the United States; and a high town-wide vaccination rate is no guarantee of low case rates.

Connecticut updated its tracking of vaccine breakthrough cases in August and is now matching positive cases with immunization records. Numbers have jumped in recent weeks, but the risk of contracting COVID after full vaccination is five times lower than before vaccination.