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The US’s daily coronavirus cases have declined 65% in the last month — a record drop in the course of the nation’s outbreak. New cases reached an all-time high of 312,000 on January 8. Since then, they’ve fallen to a weekly average of around 73,000 per day.
Dr. Martin Makary, a professor of surgery at the Johns Hopkins School of Medicine, suggested in The Wall Street Journal that the most likely explanation for the decline is that the US could be close to reaching herd immunity.
In a Thursday op-ed, Makary predicted that COVID-19 would be “mostly gone” by April.
He wrote that infections have likely been far more widespread than data suggests — so much so, in fact, that the US will soon hit a threshold beyond which the virus won’t be able to pass easily from person to person.
“The consistent and rapid decline in daily cases since January 8 can be explained only by natural immunity,” Makary wrote. “Behavior didn’t suddenly improve over the holidays; Americans traveled more over Christmas than they had since March.”
He added that vaccines “don’t explain the steep decline” since early January, because “vaccination rates were low and they take weeks to kick in.”
But many other doctors and public-health experts continue to caution that herd immunity is still a long way off in the US — particularly as more contagious variants spread.
“We’re nowhere near community immunity or population immunity or whatever people want to call it at this point,” Dr. Cindy Prins, an epidemiologist at University of Florida, told Insider. “We’re nowhere near that yet.”
Could 55% of Americans have natural immunity already?
Researchers generally estimate the coronavirus’ reproductive value — that of the original strain, at least — to be between 2 and 3 in the absence of vaccines or public-health measures. That means that to achieve herd immunity, around 50% to 67% of a population would need to have some immunity to the virus — whether through vaccination or natural infection.
“In theory, the numbers are around 70% — some say 65%, some say 75%, 80% — but it’s generally around those numbers. So it takes a while before you can get there,” Dr. Eyal Zimlichman, deputy director general at Sheba Medical Center, Israel’s largest hospital, told Insider in January.
But Makary’s op-ed suggested that “observational data” indicates the US is close to the herd immunity threshold.
Assuming testing only captures 10% to 25% of infections, he said, about 55% of Americans would have natural immunity already, based on the number of tests reported. Add to that 15% of Americans who have been vaccinated so far, he wrote, “and the figure is rising fast.”
Makary didn’t respond to Insider’s request for comment on this story.
Other factors could explain the drop in US cases
Experts say herd immunity isn’t the only possible explanation for the US’s falling case count.
California’s second lockdown, which started in December, may have partially contributed to the decline. At the peak of its outbreak, California accounted for around 40,000 of the US’s daily coronavirus cases, on …read more
Source:: Business Insider