Ashish Jha is ‘concerned’ about the delta variant in the U.S. Here’s why.

“Help an unvaccinated friend get the shot.”

Photo by Joseph Prezioso / AFP

Dr. Ashish Jha said Monday he is worried about the potential impact of the delta variant could have in the United States. 

The highly transmissible coronavirus variant, which was first detected in India and is also known as B.1.617.2, has sparked an uptick in cases in the United Kingdom that may delay officials lifting coronavirus restrictions in that country. The strain is also driving new infections in southeastern China, where doctors report patients are becoming sicker more quickly, The New York Times reports. 

At the end of last week, the delta variant accounted for 6 percent of all coronavirus infections in the U.S. 


“I’m concerned about the Delta variant,” Jha wrote on Twitter. “Why? Most contagious variant yet. Wreaked havoc in India. Spiking cases in UK. Growing rapidly in the US.” 

The dean of the Brown University School of Public Health said getting vaccinated is key to protecting against the strain.

“Help an unvaccinated friend get the shot,” he said.

Jha is not the only public health leader concerned about the delta strain.

Dr. Bob Wachter, chair of the University of California San Francisco, laid out in a lengthy Twitter thread why the variant is making him “nervous” and the argument for why more people should be taking the threat it poses seriously. 

“If you’re not vaccinated: I’d be afraid,” he wrote. “Maybe even very afraid.”

The doctor pointed out that while some places have vaccination rates topping 70 percent, about 50 percent of the country over the age of 12 remains unvaccinated. In some states, the percentage of eligible, unvaccinated individuals is higher, at about two-thirds. 

While vaccinated individuals don’t have to worry about the delta variant, particularly if they live in a community with high levels of vaccinations, unvaccinated individuals are at high risk of contracting COVID-19 if they are exposed, the doctor said. 


While the chance of unvaccinated individuals being exposed is lower in communities where more people are vaccinated, Wachter said he is scared about what could happen this fall and winter. 

“Reason: Delta,” he wrote. 

According to Wachter, the delta variant appears more infectious than the alpha variant or B.1.1.7 strain, which was first detected in the U.K. 

“This means the same exposure that a person might have had last year is now about twice as likely to result in Covid,” Wachter said. “Second, it’s looking like it is more serious, though we need more data to be sure. Third — and this is the big one — it does appear to be somewhat immune resistant. Before getting too freaked out about this, it’s worth noting that the data are reassuring, in a way: the efficacy of 2-doses of Pfizer is 88 percent, only a smidge lower than the 95 percent we’re used to, and still great.”

What is concerning, according to the doctor, is that data indicate that the first dose of Pfizer, normally about 80 percent protective, is only about 33 percent protective against the delta variant.

“What to do? For a vaccinated person, watch the Delta % in your region (currently ~6% in the U.S. & rising) & Covid cases in your community,” Wachter wrote. “If you’re seeing more cases & more Delta, I’d restore some precautions (esp. if you’re high risk) – at least indoor mask wearing (if you’ve stopped; BTW, I haven’t) in places w/ unvaxxed/unmasked folks. If you’re unvaxxed, get your shots! You may be reassured by a low, local case rate, but don’t be: it may be due to summer plus the still-low Delta fraction. Both will change.”


The US has been “lulled by the amazing efficacy of the vaccines” and because previous variants haven’t been “that nasty,” Wachter said. 

As it is, the doctor said he is now expecting to see “significant” surges in the fall in populations that have low vaccination rates because of the strain. 

COVID-19 is not yesterday’s news, Wachter stressed.

“Delta should ring the alarm & spur action,” he said. “We need FDA to fully authorize our vaccines, to step up research on boosters & faster approvals for kids. We also need > outreach to unvaxxed (incl. info on Delta) & vaccine mandates in risky settings (healthcare, nursing homes).”

Read his full thread below:


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