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A patient receives a vaccine dose

A woman receives a vaccine shot at a temporary Covid-19 vaccination site at a shopping mall in Moscow. (Photo: Vyacheslav Prokofyev\TASS via Getty Images)

New Study Shows Delta Variant's Threat to the Unvaccinated—And Partially Vaccinated

"If we continue to let the virus run loose," warned one virologist, "I'm certain we'll run out of letters and future variants will likely be worse than the current crop."

Jake Johnson

A study published in the journal Nature on Thursday found that the Delta variant of the coronavirus has the ability to dodge antibodies produced by vaccines or natural infection, an alarming discovery that comes as the ultra-contagious strain is spreading rapidly across the U.S. and throughout the world.

"We need to vaccinate the world NOW with an all-out effort led by the United States."
—Kristian Andersen, Scripps Research Institute

The new laboratory research, conducted by scientists in France, showed that just one dose of Pfizer or AstraZeneca's two-shot vaccines "barely inhibited" the Delta mutation, which has spread to more than 90 countries and is now the dominant variant in the United States.

However, the study also showed that "administration of two doses generated a neutralizing response in 95% of individuals," further spotlighting the crucial importance of the second shot. According to data from the Centers for Disease Control and Prevention (CDC), 58% of people in the U.S. above the age of 18 are fully vaccinated.

Eric Topol, director and founder of the Scripps Research Translational Institute, told STAT that the new study is important "for confirming the immune evasiveness property of Delta, which is a feature that adds to its enhanced transmissibility, making it the most formidable version of the virus to date."

The new study came in the wake of research out of Israel indicating that Pfizer's vaccine is just 64% effective in preventing Delta infection—but still 93% effective in preventing hospitalization.

During a press briefing on Thursday, Biden administration officials voiced alarm at the spread of the Delta variant across the U.S., particularly in undervaccinated clusters that could become "factories" for new mutations unless action is taken to mitigate the surge of infections.

"This rapid rise is troubling," said Dr. Rochelle Walensky, director of the CDC. "We know that the Delta variant has increased transmissibility and it is currently surging in pockets of the country with low vaccination rates."

Dr. Anthony Fauci, head of the U.S. National Institute of Allergy and Infectious Diseases, pleaded with unvaccinated Americans to get the shots, stressing that they will "protect you against the surging of the Delta variant."

The new study examining the Delta variant's ability to evade the body's immune responses came after the world reached the grim milestone of four million deaths from Covid-19, a staggering figure that experts and public health campaigners fear will continue to grow exponentially as much of the developing world remains without access to vaccines.

According to Our World in Data, just 1% of people in low-income countries—where infections are currently spiking—have received at least one vaccine dose.

"This is a horrific milestone and each one of these lives lost is a tragedy," Anna Marriott, health policy manager at Oxfam International, said in a statement Thursday. "Many of these deaths could have been prevented had the successful vaccine science been shared and production of doses ramped up by more manufacturers across the world."

Epidemiologists have long warned that highly dangerous—and potentially vaccine-resistant—coronavirus mutations could emerge unless the international community accelerates vaccine production and distribution to ensure equitable access to shots worldwide.

Kristian Andersen, a virologist at Scripps Research Institute, reiterated that message in an email to the Washington Post on Thursday.

"If we continue to let the virus run loose, then yes, I'm certain we'll run out of letters and future variants will likely be worse than the current crop—and yes, we'll likely have several circulating at the same time," Andersen wrote. "We need to vaccinate the world NOW with an all-out effort led by the United States."


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