Scientists are debating whether it makes sense to hold back the second doses of vaccines that are required for

Author : greensameblue

Publish Date : 2021-01-09 16:14:57

The challenge is immense. If the U.S. hits President-elect Joe Biden’s goal of 100 million shots in 100 days (starting with his inauguration January 20) and sustains that pace, and people get the necessary two shots each, then by the end of July, only about a third of the population will have been vaccinated.

All this math suggests it could be fall, at least, before the pandemic is apt to substantially subside.

Debate brews over one shot vs. two
Scientists are debating whether it makes sense to hold back the second doses of vaccines that are required for optimal immunity, in order to more quickly give a larger number of people some level of immunity via a first shot (the exact levels of immunity conferred won’t be accurately known until some retrospective studies can be done).

Britain has decided to delay second doses.

“I would not be in favor of that,” says Dr. Anthony Fauci, America’s top infectious-disease expert. But other experts are warming to the idea.

“If the virus is spreading slowly, we want to do the right thing and give the most vulnerable [people] two doses and [require] others to wait,” tweets Akiko Iwasaki, PhD, a professor of immunobiology at Yale University. “I am still a proponent of a two-dose vaccine but given the urgency, we can delay the second dose until more vaccines become available,” Iwasaki says.

However, the Food and Drug Administration on January 4 urged staying the course with the plans for two doses of the vaccines, which “have now shown remarkable effectiveness of about 95% in preventing COVID-19 disease in adults,” the agency said in a statement. “At this time, suggesting changes to the FDA-authorized dosing or schedules of these vaccines is premature and not rooted solidly in the available evidence.” Expect more scientific discussion and debate on this in the coming weeks.

The threshold for herd immunity just went up
The ultimate goal of vaccinations is to achieve herd immunity, whereby enough people are immune to the coronavirus that it fades away because it finds so few fresh hosts to infect. For months, scientists have estimated that the threshold could be anywhere from an optimistically low 40% to around 70%, depending on a host of factors ranging from the rigor of prevention efforts to how infectious the virus is.

“If you’ve been thinking of vaccines as the light at the end of the tunnel: Yes, that light is there, as bright as ever. But the tunnel just got a bit darker and a little bit longer.”

But already in November, Fauci was putting the threshold at 75% to 85%. Given that new strains are proving more infectious, immunity (through vaccinations and by people who’ve contracted the disease) will almost surely be on the higher end of that spectrum, many experts are now saying.

“It’s not what anyone wants to hear, but the coming months may well be the hardest of this pandemic,” tweets science writer Kai Kupferschmidt, who has written in detail about the new strains. “If you’ve been thinking of vaccines as the light at the end of the tunnel: Yes, that light is there, as bright as ever. But the tunnel just got a bit darker and a little bit longer.”

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Scientists are debating whether it makes sense to hold back the second doses of vaccines that are required for

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