Russian health authorities say tests on a laboratory worker who died at a Siberian anti-plague institute found no trace of microorganisms connected to her professional activities, while media reports have described a possible accident involving the plague bacterium. Around 189 people remain under observation for three weeks, and officials say the epidemiological situation is stable.

The 28-year-old laboratory assistant at the Irkutsk Anti-Plague Research Institute in Shelekhov died early on October 2 in intensive care at a local district hospital. Euronews identified her as Darya Shipilova. Officials recorded the cause of death as pneumonia of unknown origin.

According to Euronews, Shipilova broke a test tube containing Yersinia pestis, the bacterium that causes plague, while working with live biological material on September 25. Her condition worsened two days later. She was initially suspected of having Covid-19 before deteriorating rapidly and being placed on a ventilator. Plague is now rare in humans and treatable with antibiotics when identified early, though the bacterium continues to circulate in wild rodent populations in parts of the world.

Other reports, cited by Outbreak News Today, suggested that she may instead have been infected during a work trip to neighbouring Buryatia. Authorities have said it remains unclear how she became ill. The head of Buryatia had earlier said she possibly died of plague, while a former head of Rospotrebnadzor said the infection was most likely not plague.

Rospotrebnadzor, Russia’s consumer health watchdog, said further testing did not detect microorganisms related to Shipilova’s professional work. The agency has described the regional epidemiological situation as stable and has insisted that there is no outbreak.

Precautionary measures have nevertheless been extensive. Around 189 people have been placed under observation, according to Russian media reports, with the quarantine expected to last three weeks. Such contact monitoring is standard in suspected plague exposures because the pneumonic, lung-affecting form of the disease can spread from person to person. Several hospitals in the region have been closed. The nearby Irkutsk Aluminum Plant instructed staff to wear masks, and protective equipment was distributed in kindergartens. The plant’s director said identified close contacts had shown no symptoms and had tested negative.

The episode has caused public anxiety in Russia, where authorities initially avoided mentioning plague. It has also revived comparisons with the early days of Covid-19, when speculation about a possible laboratory leak in Wuhan became part of an unresolved debate over the pandemic’s origins.

The absence of symptoms and negative test results among close contacts is the main reassuring development so far. The three-week observation period, expected to end in late October, will be the key milestone in determining whether the incident subsides or leads to further cases.

Markets are unlikely to respond unless the situation escalates. The principal potential concern would be confirmation of plague accompanied by secondary cases among people under observation, which could generate broader health-related headlines and limited safe-haven demand. The nearby aluminium smelter is the most exposed local industry channel, as precautionary measures could attract attention while aluminium supply is already tight because of disruption in the Middle East.

White House briefings on the incident have been underway.

Earlier report: “Uh-oh, ‘lab leak’ news again ... Russian plague lab worker, 28, dies of unknown pneumonia”