COVID-19 model consensus: Quiet summer, uncertain fall

Ongoing project looks at effects of vax hesitancy, controls on pandemic

FOXBOROUGH, Mass. — In Massachusetts, the pandemic is winding down whether COVID-19 likes it or not.

One small sign: at Trader Joe’s in Patriot Place there is no longer an employee offering hand sanitizer as customers come in the door. Over at Gillette Stadium, the mass vaccination clinic is still operating. But there’s plenty of parking as Memorial Day Weekend draws near and the number either needing or wanting to get vaccinated has dwindled.

And at Johns Hopkins University, researchers are predicting quiet months ahead on the COVID-19 front.

“Most of the models agree and certainly the consensus estimate is that summer looks pretty good,” said Dr. Justin Lessler, an associate professor at the Bloomberg School of Public Health at Johns Hopkins. “We have the combination of immunity, the seasonality that we seem to be seeing in the transmission, plus a bit of remaining control all coming together to make things look good in the summer.”

Dr. Lessler is one of the many academics working these days on the COVID-19 Scenario Modeling Hub, which tracks the course of the pandemic using a number of different disease models synced into an ensemble for, hopefully, higher accuracy. Updated regularly, the latest edition of the Hub explores the effect of vaccine hesitancy and the relaxation of non-pharmaceutical interventions, such as crowd-size limits, on the pandemic.

But while summer may look good, fall is a bit more uncertain.

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“We have a larger number of models in this analysis and there really is a strong indication that if we aren’t careful there will be a resurgence in the fall,” said Dr. Katriona Shea, a professor of Biology at Penn State University who also works on the Modeling Hub.

“And this is without taking into account the idea there may well be new variants coming into the country with higher transmissibility, which we’re already seeing with variants that originated in India, have moved to the UK and have now spread here.”

The worst scenario for fall, according to the Hub, would occur with an 80% reduction in the use of control measures between now and October coupled with a vaccine acceptance rate of 68%, considered ‘high hesitancy.’

‘Low hesitancy’ is considered a vaccine uptake of 83% by October, Lessler said.

“If we assume everybody who says they might get the vaccine gets it, in surveys we get around 83% of the age-eligible population,” Lessler said. “So, 12-and-over getting vaccinated. If you assume those people who are on the fence don’t get it, you get around 68% of the people ultimately getting vaccinated. So, we’re basing it on what people are telling us they’re likely to do.”

“The prognosis is reasonable, if we are careful and if we can get high vaccination. But if not, given the current relaxation of masking rules that the CDC has just implemented, I do think it’s possible that we might see some resurgence in the fall and that we might need to go back to using masks again,” Shea said.

Her biggest worry?

“The most incredible worry is a variant will come in that totally escapes all our vaccines,” Shea said. “That would put us back to square one. We’d be starting from scratch because nothing we have in place would be efficacious against it.”

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