Nearly a quarter of travelers who flew from China to Italy in late December tested positive for COVID, according to a new study — one that offers a glimpse of transmission occurring from the eastern superpower. to the rest of the world.
Almost 23% of the 565 passengers on four flights at the airports of Rome and Milan from December 26-29 carried the highly contagious disease, according to a study published last week on the infectious disease that journal Eurosurveillance. About 42% of the passengers on a flight were infected.
The study probably provides a better understanding of the number of infected people on the trips, Fortune experts said. Some passengers may be too early in their infection to test positive. That number, however, is likely offset by others who test positive but are too late in the course of their infection to be contagious.
About 11% of the travelers in the study were “likely to infect others, but the rest may not be,” Dr. Jay Varma, chief medical adviser at the New York-based think tank Kroll Institute, told Fortune, citing the study. Varma’s two-decade career at the US Centers for Disease Control and Prevention included postings in China.
And that’s the number that matters most to travelers, he says: “What percentage of people who get on a plane are likely to get off me?”
Countries such as the US, Britain, France, Australia, Canada, Japan, and others require travelers from China to provide proof of a recent negative COVID test result prior to entry. It comes as the country’s COVID infections have exploded—an increase that began before the lifting of “zero COVID” restrictions in early December. The level of COVID began to rise in the country during the widespread policy protests, and probably served as super-spreader events, Dr. Ali Mokdad, professor at IHME and a former senior epidemiologist at the US Centers for Disease Control and Prevention, said before luck.
Such restrictions on incoming travelers from China are “understandable,” given the inability of countries to conduct a thorough risk assessment of the situation in China, the director of emergencies of the World Health Organization, Michael Ryan said at a news conference last week, stressing that such measures are not travel restrictions.
COVID data coming from the country has long been uncertain, and the country stopped releasing daily updates last month. In a major update, Chinese health officials said this weekend that the country has seen nearly 60,000 COVID-19 deaths since Dec. 8 — more than an 11-fold increase over all time of previously reported COVID deaths.
But the number is “almost certainly a remarkable underestimation,” Dr. Stuart Ray,
vice chairman of medicine for data integrity and analysis at the Johns Hopkins Department of Medicine, told Fortune: “The number could be 10 times that reported, due to a lack of transparency.”
Almost all of the sequenced samples obtained by the authors of the study were Omicron subvariants, mostly off-shots of BA.5, BF.7, and BQ.1.1, which line up with the data released in China.
Nearly a quarter of travelers who participated in the CDC’s voluntary COVID testing and sequencing program tested positive for COVID during the week of Christmas, the most recent period for which data is available on the agency’s website. The CDC did not respond to Fortune’s request for what percentage of travelers from China tested positive.
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