China links COVID outbreak to man’s jog through a park; Scientists skeptical - Ars Technica

Enlarge / Runner successful Shanghai, China.

In the aboriginal greeting of August 16, a 41-year-old antheral successful China's southwest-central municipality of Chongqing got up and went for a jog on a water successful a section outdoor park—something that should person been a pleasant, if not unremarkable, outing. But what truly happened during that 35-minute jaunt has present sparked planetary alarm and debate, with immoderate scientists doubtful of China's startling account.

According to the Chinese Center for Disease Control and Prevention, the unmasked antheral infected 33 unmasked parkland visitors and 2 unmasked parkland workers with the coronavirus omicron subvariant BA.2.76 during his abbreviated run. The bureau claimed transmission occurred successful fleeting outdoor encounters arsenic helium trotted past radical connected a four-meter-wide ft path. Many others were infected without immoderate adjacent encounter. Twenty of the 33 infected parkland goers became infected by simply visiting outdoor areas of the parkland the jogger had antecedently passed through, including an entranceway gate. The 2 infected workers, meanwhile, rapidly passed the corruption connected to 4 different colleagues, bringing the jogger's parkland outbreak full to 39.

To enactment these antithetic conclusions, the CCDC cited lawsuit interviews, parkland surveillance footage, and SARS-CoV-2 familial data, which reportedly linked the cases but is notably absent from the report.

The report's claims, if accurate, would suggest a important update is successful bid for our existent knowing of SARS-CoV-2 transmission risks. Though transmission outdoors is known to beryllium possible, it's considered acold little apt than transmission indoors, wherever microorganism particles tin bent successful stagnant aerial and physique up successful enclosed spaces implicit time. Outdoor encounters that are transient are particularly not considered a important risk, arsenic immense volumes of moving aerial rapidly disperse infectious doses of viral particles. For the aforesaid reason, SARS-CoV-2 is not thought to linger successful menacing clouds outdoors successful an infected person's wake.

For now, experts extracurricular China are not revising their reasoning connected transmission risks, citing the report's missing familial information and different questionable conclusions.

Missing data

Given China's strict "zero COVID" strategy, the CCDC dismissed outright the anticipation that infections were portion of an undetected outbreak successful the greater community, calling vulnerability to the jogger (aka "patient zero") the "only imaginable exposure."

The CCDC claims that familial information links each the cases together, showing that diligent zero was the root of the 39 infections. Specifically, they study that 29 of the 39 cases had "the nonstop aforesaid cistron sequencing arsenic Patient Zero; 5 cases had a mutation tract added to Patient Zero’s cistron sequence; and the different 5 cases could not beryllium sequenced due to the fact that of unqualified specimens." But determination is nary sequencing information included with the report, and it's unclear what sequencing was really done to enactment their claims.

"If they had series information that showed 29 cases had identical genomes to 'patient zero,' that would suggest that each the cases came from a azygous source," virologist Angela Rasmussen told Ars. Rasmussen is simply a researcher astatine the Vaccine and Infectious Disease Organization astatine the University of Saskatchewan and an affiliate astatine Georgetown University Center for Global Health Science and Security.

"But," she said, "it’s unclear whether they did full genome sequencing of each the cases, what sequencing level they utilized (Illumina vs Nanopore) etc." The study lone mentions "gene sequencing," which whitethorn suggest lone partial genome sequencing, not "whole genome sequencing" that would decidedly bespeak a nonstop nexus betwixt the cases. Without knowing the sequencing information and methods, it's intolerable to corroborate if the jogger was the source.

The CCDC besides offers a puzzling mentation of however the jogging diligent zero came to beryllium infected successful the archetypal place.

Patient zero

According to the CCDC, the antheral became infected from a vague "exposure to contaminated hose environments." The antheral had taken a travel from Chongqing to the bluish metropolis of Hohhot connected August 11, and flew backmost to Chongqing connected August 13—three days earlier his jog. Neither formation had immoderate known SARS-CoV-2 cases connected committee that could explicate the man's infection. But, the level helium took for the returning travel had transported 4 SARS-CoV-2-positive passengers the time before, connected August 12.

On August 12, 4 passengers from Tibet took the level from Chongqing to Hohhot and aboriginal tested affirmative successful Hohhot. The plane, meanwhile, wasn't disinfected aft their flight, and the Chongqing antheral boarded the adjacent time and sat (in spot 33K) adjacent wherever 3 of the infected passengers had been sitting (seats 34A, 34C, 34H). It's unclear however the antheral could person go infected this way—SARS-CoV-2 is not known to linger successful the aerial for specified agelong periods, and transmission from contaminated surfaces is rare. Moreover, the study does not bespeak that immoderate different passengers connected the formation besides became infected, including radical who really sat successful the aforesaid seats arsenic the passengers from Tibet. But diligent zero was infected with BA.2.76, which was circulating successful Tibet, which led the CCDC to reason a connection.

"I deliberation it’s besides precise dubious that 'patient zero' was infected connected that plane," Rasmussen said. "I noticed that the anterior formation with the passengers that were supposedly the root of the corruption came from Chongqing—that could suggest cryptic dispersed of BA.2.76 successful Chongqing, not (just) Tibet arsenic the insubstantial claims. In this case, if a full clump of radical successful Chongqing person BA.2.76, the sequencing information mightiness conscionable constituent to a overmuch larger outbreak successful Chongqing, but you’d request the existent sequencing information to truly fig retired what’s going on.

"Bottom line: immoderate claims astir what the information really shows depends connected really including the information successful the paper," she said. "Otherwise it’s conscionable speculation."