The new analysis of blood samples taken from 24,000 Americans early last year is the latest and largest study to suggest that the novel coronavirus may have emerged in the United States in December 2019.
Although the analysis is not conclusive amid the skepticism of some experts, federal health officials are increasingly accepting a timeline in which small numbers of “Covid-19″ infections may have occurred in the United States before the world became aware of the emergence of a dangerous new virus in China.
“The studies are pretty consistent,” said Natalie Thornberg, principal investigator on the US Centers for Disease Control and Prevention’s Respiratory Virology Immunology team. “There may have been very rare and sporadic cases here earlier than we were aware of. It was not widespread and did not spread until late February.”
She added that these findings underscore the need for countries to work together and identify newly emerging viruses as quickly and collaboratively as possible.
The coronavirus epidemic emerged in Wuhan, China in late 2019. The first officially identified US infection was a traveler from Washington state who returned from Wuhan on January 15 and sought medical help on January 19.
CDC officials initially said that the spark for the outbreak in the United States arrived over a three-week period from mid-January to early February. But research since then — including some by the CDC — has suggested a small number of infections occurred earlier.
A study led by the Centers for Disease Control and Prevention (CDC) published in December 2020, which analyzed 7,000 samples of American Red Cross blood donations, indicated that the virus infected some Americans as early as mid-December 2019.
The latest study, published online Tuesday in the journal Clinical Infectious Diseases, was conducted by a team that includes researchers at the National Institutes of Health. They analyzed blood samples from more than 24,000 people across the country, collected in the first three months of 2020 as part of a long-term study called “All Of Us”, which seeks to track a million Americans over a period of years to study health.
Like the CDC study, these researchers looked for antibodies in the blood that are taken as evidence of infection with the Corona virus, and can be detected as early as two weeks after a person is first infected.
The researchers say that seven study participants – three from Illinois and one each from Massachusetts, Mississippi, Pennsylvania and Wisconsin – were infected earlier than any case of “Covid-19” originally reported in those states.
One of the Illinois cases became infected on Christmas Eve, said Keri Altoff, an assistant professor at the Johns Hopkins Bloomberg School of Public Health and lead author of the study.
It can be difficult to distinguish between antibodies that neutralize SARS-CoV-2, the virus that causes COVID-19, and antibodies that fight other coronaviruses, including those that cause the common cold. Researchers in both the NIH and CDC studies used multiple types of tests to reduce false positives, but some experts say it’s still possible that infection with other coronaviruses rather than the pandemic strain caused their 2019 positive results.
William Hanage, an expert in disease dynamics from Harvard University, said: “While it is entirely plausible that the virus entered the United States much earlier than is usually estimated, this does not mean that it is necessarily strong enough evidence to change the way we think about this. matter.”
The National Institutes of Health researchers have not yet followed up with the study participants, to see if any of them had traveled outside the United States before the infection. But they found it worth noting that the seven did not live in or near New York City or Seattle, where the first wave of cases was concentrated in the United States.
“The question is how and where the virus took its seeds,” Altov said. She added that the new study indicates that “it is likely that it has been published in multiple places in our country.”
Source: The New York Post