Mass. vaccination goal not high enough to stop Delta variant

BOSTON — Massachusetts may have to readjust its set-point for herd immunity, thanks to the anticipated dominance of the Delta variant of COVID-19.

At least that’s the view of Samuel Scarpino, an assistant professor at Northeastern University and director of the school’s Emergent Epidemics Laboratory.

“The governor has targeted 60 percent of the entire state for vaccination, which was a good goal pre-Delta,” Scarpino said. “But with this new variant, that’s really not going to be enough to protect unvaccinated individuals like school children.”

Scarpino said you only have to look at Israel to know why that’s not enough. That country, much lauded in recent months for its vaccination efforts, is now feeling the effects of the Delta variant.

“They’re at about 60 percent of the population fully vaccinated and we’re hearing reports of outbreaks in schools in unvaccinated children and rising case numbers due to the Delta variant,” Scarpino said.

That raises the discomforting specter of what might happen come September here. At present, the Delta variant is the cause of around 10 percent of infections in the U.S. But its share is rising fast -- and with good reason.

“It’s probably 40 to 60 percent more transmissible than the B.1.1.7 variant,” according to preliminary data, Scarpino said. “There’s quite a bit of risk from this variant especially in undervaccinated populations.”

B.1.1.7, formerly known as the British variant (and now the Alpha variant) was, itself, 30-40 percent more transmissible than what many would consider ‘original’ COVID (though the original COVID had undergone some mutations).

Given that, Scarpino thinks another surge is very possible if vaccination numbers don’t pick up.

New data from the COVID-19 Scenario Modeling Hub suggests that even with high vaccination rates, an active variant situation could boost daily case numbers well into fall.

With low vaccination rates, the situation could deteriorate markedly by Thanksgiving, the models suggest, with the U.S. possibly racking up more than 200,000 cases per day.

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