Author: Mike Staub
AP Medical Writer
New York (Associated Press)-A new analysis of the blood samples of 24,000 Americans collected early last year is the latest and largest study showing that this new type of coronavirus emerged in the United States in December 2019- -A few weeks before health officials first detected the case.
The analysis is uncertain, and some experts remain skeptical, but federal health officials are increasingly accepting a timetable that a small number of COVID-19 infections may have occurred in the United States before the world became aware of the outbreak of a dangerous new virus in China.
“These studies are very consistent,” said Natalie Thornberg of the Centers for Disease Control and Prevention.
“Very rare and sporadic cases may have occurred earlier than we realized. But it is not common, and it didn’t become common until late February,” said Thornburg, the lead researcher of the CDC Respiratory Virus Immunology Group.
She added that these results emphasize the need for countries to work together and identify emerging viruses as quickly and collaboratively as possible.
The pandemic coronavirus emerged in Wuhan, China at the end of 2019. The first officially confirmed infected person in the United States was a traveler-a Washington State man who returned from Wuhan on January 15 and sought help in a clinic on January 19.
CDC officials initially stated that the spark that triggered the outbreak in the United States arrived in the three-week period from mid-January to early February. But research since then-including some by the CDC-has shown that a small number of infections occur earlier.
A CDC-led study was published in December 2020 and analyzed 7,000 samples from blood donations from the American Red Cross, showing that the virus infected some Americans as early as mid-December 2019.
The latest study was published online in the journal Clinical Infectious Diseases on June 15 and was completed by a team including researchers from the National Institutes of Health. They analyzed blood samples from more than 24,000 people across the country. These samples were collected in the first three months of 2020 as part of a long-term study called “All of Us”, which aims to track 1 million Americans over the years People to study health conditions.
Like the CDC study, these researchers look for antibodies in the blood as evidence of coronavirus infection, which can be detected as early as two weeks after a person’s first infection.
The researchers said that seven of the nine study participants — three from Illinois and one from Massachusetts, Mississippi, Pennsylvania, and Wisconsin — were earlier than any COVID-19 cases initially reported in these states. be infected.
Keri Althoff, an associate professor at the Bloomberg School of Public Health at Johns Hopkins University and lead author of the study, said a case in Illinois was infected as early as Christmas Eve.
It may be difficult to distinguish antibodies that neutralize SARS-CoV-2 (the virus that causes COVID-19) from antibodies against other coronaviruses, including some that cause the common cold. Researchers in NIH and CDC studies use multiple types of tests to minimize false positive results, but some experts say that their positive results in 2019 may still be infected by other coronaviruses rather than pandemic strains.
William Hanage of Harvard University said: “Although the virus was introduced to the United States much earlier than usual imagined, this is entirely possible, but it does not mean that it must be enough to change our situation. Strong evidence of opinion.” University disease dynamics expert.
NIH researchers have not followed up with study participants to see if anyone left the United States before becoming infected. But they found that it is worth noting that these seven people did not live in or near New York City, Seattle, or Seattle, where the first wave of cases in the United States was concentrated.
“The question is how and where the virus is sown,” Alsoff said. She added that this new study shows that “it may be sown in multiple places in our country”.