Topline
Despite the emergence of delta as the dominant variant of Covid-19 in the U.S., nearly all of the antibodies produced by the Pfizer vaccine are able to neutralize it, according to a study published Monday, underscoring the protection offered by vaccinations in a pandemic where nearly all cases—and virtually all serious cases—are among the unvaccinated.
Pharmacist Tiffany Aljets fills a syringe for a Covid-19 vaccination at the Iowa State Fair on ... [+]
Key Facts
In a lab, researchers exposed cells with antibodies from the Pfizer vaccine to the original strain of Covid-19 and four variants.
The delta and alpha variants were neutralized by all but one of 13 antibodies that are developed in someone who’s received the Pfizer vaccine, researchers from Washington University School of Medicine in St. Louis wrote in the peer-reviewed journal Immunity.
While beta and gamma eluded some antibodies, eight of the 13 still found and stopped both variants.
Of the five antibodies that were effective against the original strain, all five neutralized the delta variant—making it less robust than the original, despite its superior ease of spreading.
Crucial Quote
“In face of vaccination, delta is relatively a wimpy virus,” said Ali Ellebedy, a senior co-author of the study and a professor of pathology and immunology at Washington University School of Medicine in St. Louis, in a press release announcing the study. “If we had a variant that was more resistant like beta but spread as easily as delta, we’d be in more trouble.”
Key Background
The delta variant is more than twice as contagious as the original strain of the coronavirus, which is why it so quickly became the dominant version in the U.S. and many other countries. But there is a difference between the ability of a virus to spread easily and its ability to sneak by antibodies. “The fact that delta has outcompeted other variants does not mean that it’s more resistant to our antibodies compared to other variants,” said Jacco Boon, Ellebedy’s co-author and colleague at the medical school. That’s why people who have been vaccinated have been shown to have such strong protection against the delta variant despite its rapid spread among the unvaccinated. With 49% of U.S. residents still not fully vaccinated, however, the delta variant has more chances to break through and infect people who have received their shots. If someone who is vaccinated does catch the delta variant, they can still spread it, although they seem to be contagious for a shorter period of time.
Contra
Different vaccine studies have found a range of effectiveness against the delta variant: from nearly 90%, in a Pfizer study, to 64% in an Israeli study. Even in the Israeli study, though, the vaccine was shown to be 93% effective at preventing severe cases of the virus.
Big Number
0.29%. That’s how many Covid-19 cases in Alaska were in fully vaccinated people, according to data from 25 states analyzed by the Kaiser Family Foundation. Of the states, Alaska had the highest percentage of Covid-19 breakthrough cases. In Connecticut, the state with the lowest share, 0.01% of total cases were among those fully vaccinated.
Further Reading
County Hit Early By Delta Had More Breakthrough Cases, CDC Study Finds (Forbes)
Infectious Delta Variant Is Now The Dominant Covid Strain In US, CDC Says (Forbes)
