In the early morning hours of August 16, a 41-year-old man from Chongqing, central southwestern China, got up to go jogging along a lake in a local outdoor park. , going out. But what actually happened during his 35-minute excursion is now causing international alarm and debate, with some scientists questioning China’s astonishing explanation.
According to the Chinese Center for Disease Control and Prevention, The unmasked man infected 33 unmasked park visitors and 2 unmasked park workers with the Omcron subvariant BA.2.76 of the coronavirus during his short run. I was allowed to. The agency claimed the infection occurred in a fleeting encounter outdoors as he passed people on a four-meter-wide trail. Of his 33 infected park-goers, 20 of him became infected simply by visiting outdoor areas of the park (including entrance gates) that joggers had previously visited. Meanwhile, two of his infected workers quickly spread the infection to four of his other colleagues, bringing the Joggers outbreak at his park to 39 people.
To support these extraordinary conclusions, the CCDC cited case interviews, park surveillance footage, and SARS-CoV-2 genetic data.
If the report’s claims are accurate, they suggest that our current understanding of the risk of SARS-CoV-2 transmission needs an important update. It is known that it can be transmitted outdoors, but it is much more likely than indoors where viral particles can become lodged in stagnant air and accumulate over time in an enclosed space. considered to be of low quality. Temporary outdoor encounters are not considered a particularly significant risk. This is because large amounts of air movement disperse the infectious dose of virus particles rapidly. For the same reason, SARS-CoV-2 is not expected to linger outside in fearsome clouds at the wake of an infected person.
So far, experts outside China have not revised their views on infection risk, citing missing genetic data in the report and other questionable conclusions.
missing data
Given China’s stringent “No COVID” strategy, the CCDC called exposure to joggers (a.k.a. “zero patient”) the “only possible exposure” when the infection was detected in the larger community. completely dismissed the possibility that it was part of an unexplained outbreak.
The CCDC claims genetic data has linked all cases, indicating that patient 0 was the source of 39 infections. Specifically, in 29 of the 39 cases, “exactly the same gene sequencing as in patient 0 was performed, in 5 cases the mutation site was added to the gene sequence in patient 0, and in the remaining 5 cases the specimen was ineligible. It could not be sequenced.” However, the report did not include any sequencing data, and it is unclear what sequencing was actually done to support their claims.
“Having sequence data showing that 29 cases have the same genome as ‘patient 0’ would suggest that all cases came from a single source,” says virologist Angela Rasmussen. told Ars. Rasmussen is a researcher at the University of Saskatchewan’s Vaccines and Infectious Diseases Mechanism and an affiliate of Georgetown University’s Center for Global Health Science and Security.
“However, it is unclear whether they performed whole-genome sequencing of all cases, which sequencing platform they used (Illumina vs. Nanopore), etc.” Only “gene sequencing” was mentioned in the report. , which may imply only partial genome sequencing and not ‘whole genome sequencing’, which clearly indicates a direct link between cases. Without knowing the sequencing data and methods, it is impossible to confirm whether the jogger was the source of infection.
The CCDC also offers a cryptic explanation for how Patient 0, who was jogging, became infected in the first place.
patient zero
According to the CCDC, the man became infected from a vague “exposure to a contaminated airline environment.” The men traveled from Chongqing to the northern city of Hohhot on August 11 and flew back to Chongqing on August 13, three days before jogging. Neither flight had a known case of SARS-CoV-2 in him that could explain the man’s infection. However, the plane he took to return home had carried four SARS-CoV-2-positive passengers on the previous day, August 12.
On August 12, four passengers from Tibet boarded a flight from Chongqing to Hohhot, where they later tested positive. Meanwhile, the plane had not been disinfected after the flight, and the Chongqing man boarded the next day and sat near (seat 33K) where three of the infected passengers sat (seats 34A, 34C, and 34H). It is unknown how the man became infected in this way. SARS-CoV-2 is not known to remain in the air for such a long time, and transmission from contaminated surfaces is rare. Furthermore, reports do not show that other passengers on the flight were also infected, including those who actually sat in the same seat as the passengers from Tibet. BA.2.76, the CCDC concluded a link.
“I also think it’s highly doubtful that ‘Patient Zero’ got infected on that plane,” Rasmussen said. “We noticed that the previous flight carrying the suspected source of infection passengers came from Chongqing. Sequencing data may only point to a much larger outbreak in Chongqing, as many people in Chongqing have BA.2.76 in this case. But to understand what’s really going on, we need real sequencing data.
“In short, the claim about what the data really show depends on whether the paper actually contains the data,” she said. “Otherwise it’s just speculation.” .”
