- Daily cases of American coronavirus have dropped by an average of 74% over the past six weeks.
- Experts are hopeful that the US outbreak has taken a turn.
- Economist Ian Shepherdson predicted the “effective end to the US COVID crisis” before May.
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As coronavirus vaccinations increased in the US at the beginning of this year, the hopeful progress is overshadowed by the fear of variants. Scientists were concerned that B.1.1.7, the more contagious variant discovered in the UK, would keep coronavirus cases high during the winter, although more people got shots.
“The restrictions currently being applied in the US are, on average, not strict enough to control B.1.1.7,” Panamon Macroeconomics chief economist Ian Shepherdson wrote on February 12. He added that the US was “in a race” between B.1.1.7 and the rate of vaccinations. “
But this week, Shepherdson changed his tune: “If B.1.1.7 cases do not accelerate significantly next month, it would be realistic to call the effective end to the US COVID crisis – at least in terms of the case and hospitalization numbers – by the end of April, “Shepherdson wrote Monday.
Daily U.S. cases have dropped by an average of about 74% over the past six weeks. The country recorded less than 53,000 cases on Monday – its lowest daily score since October. On Tuesday, however, daily affairs rose to nearly 68,000.
Daily deaths have also decreased by 38% over the past six weeks, while daily hospitalizations have decreased by 55%.
“The balance is more optimistic and less cautious than four weeks ago,” Andrew Noymer, associate professor of public health at the University of California, Irvine, told Insider.
Such a sharp decline in infections and diseases “was not necessarily predicted by people like me,” he added.
Many experts are now hopeful that the US outbreak has taken a turn – at least for the next few months.
Why did things drop so suddenly?
Diners sit outdoors on May 29, 2020 in a restaurant in Alexandria, Virginia.
REUTERS / Kevin Lamarque
Scientists do not fully understand why cases have fallen so dramatically in the past six weeks.
Shepherdson suggested that B.1.1.7 could not spread as fast as some epidemiologists feared.
“We do not yet see any signs that the spread of the more contagious B.1.1.7 variant is slowing down, even in Florida, where it is most prevalent,” he wrote.
Leana Wen, a visiting professor of health policy and management at George Washington University, told Insider that the biggest reason is probably that the holidays are over.
The US was “previously at a peak with the boom of Thanksgiving and Christmas, that we will eventually descend from there,” she said.
Another contributing factor may be that the reduced testing means fewer cases are recorded: the average daily tests have decreased by 30% over the past six weeks. But that does not explain the significant decline in hospitalizations and deaths.
Weather can also affect the dynamics of coronavirus outbreaks, as some studies have shown that warmer conditions can slow down the transmission of the coronavirus. But overall, the US did not see dramatic temperature changes from January to February.
“It’s probably a combination of things – a combination that there are enough people who are already infected and that people are being vaccinated, so there is some protection,” Wen said.
Some experts believe that the combination of natural immunity and freedom of immunity could push the US even closer to a herd immunity threshold.
Is herd immunity closer than we realize?
Alameda County workers stand up for coronavirus vaccines outside the St. Louis area on Jan. 8, 2021. Rose Hospital in Hayward, California.
Jessica Christian / The San Francisco Chronicle / Getty Images
Most scientists do not believe that the US has achieved herd immunity – the threshold within which the virus can no longer spread easily from person to person. But some experts think we may be close.
Dr. Martin Makary, a professor of surgery at the Johns Hopkins School of Medicine, wrote in The Wall Street Journal last week that “the consistent and rapid decline in daily cases since January 8 can only be explained by natural immunity.”
Based on that, he predicted that COVID-19 would be mostly by April.
Shepherdson also suggested on Monday that the immunity of the herd by April ‘will not be far off’.
Scientists calculate herd immunity based on a virus’ reproductive value: the number of people infecting one sick person on average. Researchers generally estimate the reproductive value of the coronavirus – the original virus, not a variant – between 2 and 3 without interventions such as vaccines or public health measures.
This means that approximately 50% to 67% of the US population will need to have some degree of immunity – whether through vaccination or natural infection – to bring about herd immunity.
But studies suggest that B.1.1.7 may increase the reproductive value of the virus by 0.4 to 0.9. In that case, the threshold for herd immunity would be higher: up to 75% of the US population would probably have to develop immunity.
“I do not think there is a chance that we can vaccinate 80% of Americans by July, so at that point we will not achieve herd immunity,” Wen said.
However, she added that the US is likely to see a “significant decrease” in infections by May, and a similar decrease in hospitalizations in deaths that follow.
This period of lower infection rates, Wen said, “is our opportunity to gain as much immunity in the community as possible” through vaccinations.
Shepherdson expects that as the U.S. draws closer to herd immunity, more businesses will reopen.
“The gradual reopening of the service sector that is currently underway will accelerate over the next two months,” he said, “with most of the economy open for more than enough time for Memorial Day.”
Andrew Dunn reported.