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CDC director Rochelle Walensky says Provincetown outbreak proves vaccines are working

Dr. Rochelle WalenskySusan Walsh/Associated Press

US Centers for Disease Control and Prevention director Dr. Rochelle Walensky said Monday that the COVID-19 outbreak on Cape Cod shows that vaccines and other public health measures work.

Walensky spoke during a White House briefing about the state of the COVID-19 pandemic several days after the CDC changed its mask guidelines to recommend people wear masks in indoor public places in certain areas of the country — partially in response to an outbreak in Provincetown in which hundreds of people tested positive.

Officials have put the total number of cases associated with the cluster at around 900, including 231 Provincetown residents.


Most of the infections are from the Delta variant. Authorities have said about three-quarters of the infected people had been vaccinated.

Though she acknowledged that the high rate of cases among vaccinated people in the Provincetown outbreak prompted questions about whether the Delta variant can be spread by vaccinated people, Walensky said some of the data were encouraging: There were just seven hospitalizations as a result of the outbreak, and zero deaths.

“Our vaccines did exactly what they were supposed to do: prevent severe disease, hospitalization, and death. Furthermore as cases increased, local public health officials implemented a package of public health prevention strategies, including increased testing, contract tracing, and indoor mask wearing, and within two weeks test positivity fell from a peak of 15.1 percent to 4.6 percent,” Walensky said.

“Public health prevention strategies work,” she added.

Provincetown Town Manager Alex Morse said Monday the town is making strong progress in fighting the COVID-19 cluster.

“We are well on our way to containment,” Morse wrote in a Facebook post, adding that as of Monday, the total number of active cases among Provincetown residents had decreased to 59.

He said the number of people recovering from the virus each day “far exceeds” the number of new cases being reported.


According to Morse, the test positivity rate has plummeted from a high of 15 percent on July 15 to a “new low” of 3.3 percent Saturday and 4 percent Sunday.

The CDC report looked at 469 COVID-19 cases identified among Massachusetts residents who had traveled to Provincetown between July 3 and July 17, including 346 fully vaccinated people. About 274 of the vaccinated people with so-called breakthrough infections showed symptoms, most commonly cough, headache, sore throat, muscle pain, and fever.

Dr. Anthony Fauci echoed Walensky’s comments, and said even when breakthrough infections occur among vaccinated people, the symptoms are typically mild.

“We’ve already seen that from the experience in Massachusetts, in Provincetown, and we see it in all other situations,” Fauci said.

Public health authorities have continually emphasized that breakthrough infections are rare, and that vaccinated people who contract the virus are unlikely to become severely ill.

“What’s abundantly clear is that the vaccines are working. There were only a few hospitalizations and there were no deaths. In addition, the outbreak came under control quickly,” Sam Scarpino, the managing director of pathogen surveillance at the Rockefeller Foundation, said in an e-mail.

“Given the high case rates across the US, we need to focus on NPIs [non-pharmaceutical interventions], e.g., masking and testing, to ensure that unvaccinated children and individuals with health conditions that prevent vaccination and/or the development of full immunity are protected. However, even against Delta, the vaccines are protecting individuals from severe disease and interrupting transmission,” said Scarpino, who is an affiliate professor at Northeastern University.


The United States is grappling with rapidly rising coronavirus cases as a result of the highly contagious Delta variant of the coronavirus, particularly in areas of the country with relatively low vaccination rates.

“While we desperately want to be done with this pandemic. COVID-19 is clearly not done with us,” Walensky said as she urged people to get vaccinated.

Christina Prignano can be reached at christina.prignano@globe.com. Follow her @cprignano. Travis Andersen can be reached at travis.andersen@globe.com.