Current News



Unraveling the mysterious mutations that make delta the most transmissible COVID virus yet

Liz Szabo, Kaiser Health News on

Published in News & Features

Mutations in this region make monoclonal antibodies less effective in treating COVID and increases the delta variant’s ability to escape vaccine-generated antibodies, Akselrod said. That may explain why vaccinated people are slightly more likely to become infected with delta, causing mostly mild illness but allowing them to transmit the virus.

Scientists say it’s impossible to predict exactly how delta will behave in the future, although Topol said, “It’s going to get worse.”

Topol noted that delta outbreaks tend to last 10 to 12 weeks, as the virus “burns through” susceptible populations.

If the United States continues to follow a pattern seen in the United Kingdom and the Netherlands, infections could rise from the current seven-day moving average of 42,000 cases to 250,000 a day. Yet Topol said the United States is unlikely to suffer the high death rates seen in India, Tunisia and Indonesia because nearly half the population here is fully vaccinated.

While some studies have concluded that the Johnson & Johnson vaccine stimulates strong and persistent antibodies against delta, a new report found that antibodies elicited by one shot may not be enough to neutralize delta. Authors of that study, from the New York University Grossman School of Medicine, suggested a second dose may be needed.

Two doses of the Pfizer-BioNTech vaccine protect 94% of people from any symptomatic infection by the alpha variant, compared with 88% against the delta variant, according to a new study in the New England Journal of Medicine. Two doses of the AstraZeneca vaccine protect 75% of people from alpha and 67% from delta.

Cooper said COVID-19 vaccines offer remarkably good protection. “I will always celebrate these vaccines as the scientific achievements of my lifetime,” he said.


The best way to slow down the evolution of variants is to share vaccines with the world, vaccinating as many people as possible, Bedford said. Because viruses undergo genetic changes only when they spread from one host to another, stopping transmission denies them a chance to mutate.

Whether the coronavirus evolves more deadly variants “is totally in our hands,” Cooper said. “If the number of infections remains high, it’s going to continue to evolve.”

By failing to contain the virus through vaccination, wearing masks and avoiding crowds, people are allowing the coronavirus to morph into increasingly dangerous forms, said Dr. William Haseltine, a former Harvard Medical School professor who helped design treatments for HIV/AIDS.

“It’s getting better, and we’re making it better,” he said. “Having half the population vaccinated and half unvaccinated and unprotected — that is the exact experiment I would design if I were a devil and trying to design a vaccine-busting virus.”

(This story was produced by KHN (Kaiser Health News), a national newsroom that produces in-depth journalism about health issues. Together with Policy Analysis and Polling, KHN is one of the three major operating programs at KFF (Kaiser Family Foundation). KFF is an endowed nonprofit organization providing information on health issues to the nation.)

©2021 Kaiser Health News. Visit Distributed by Tribune Content Agency, LLC.