Russian authorities have sought to calm international concern after the death of a young technician employed at a Siberian laboratory that studies plague and other infectious diseases. Yet contact isolation, hospital restrictions and limited official disclosures have fueled fears that the full story remains hidden.

The technician worked at the Irkutsk Research Anti-Plague Institute of Siberia in southeastern Russia. Independent regional news outlet Lyudi Baikala identified her as Darya Shipilova, 28, and reported that she was hospitalized on September 29.

Shipilova is believed to have died at a hospital in Shelekhov, about 12 miles southwest of Irkutsk. One of her friends told CNN that she died on October 2 but did not confirm further details about her illness or death.

Rospotrebnadzor, Russia’s health and consumer watchdog, said Shipilova died from pneumonia of “unknown” origin. The agency played down suggestions that the illness was connected to her laboratory work, while unverified reports suggested either a possible laboratory leak or infection during travel to another region.

On Wednesday, Rospotrebnadzor said there was no epidemic risk and that authorities were winding down their response. It reported that medical monitoring had been completed for “over 90%” of the deceased worker’s contacts and that no “dangerous” pathogens had been detected.

The first public indication of concern came on October 2, when Irkutsk Governor Igor Kobzev wrote on Telegram that Rospotrebnadzor head Anna Popova had convened an “extraordinary meeting.” He said officials were discussing a suspected “particularly dangerous infection” involving a regional resident.

Kobzev did not identify plague, but neighboring Buryatia’s leader, Alexey Tsydenov, initially said the woman “died of plague in the Irkutsk region.” Russian media reported that the statement was later changed to say she had “possibly died from plague.”

The uncertainty translated into visible precautions at hospitals. Ulyana Gavryunina, a blogger from Angarsk who was 40 weeks pregnant, told CNN she had to change maternity hospitals because quarantine restrictions prevented her husband from accompanying her during labor.

At the Irkutsk City Perinatal Center, Gavryunina said her mother was denied entry. Staff checked Gavryunina’s temperature, examined her tongue, required a mask and hand sanitizer, and asked her to complete two questionnaires.

One questionnaire was titled “Checklist for Suspected Highly Dangerous Infectious Disease Plague” and listed symptoms including chest pain and high fever. Gavryunina said staff did not mention plague, instead describing an unidentified “new virus” and saying precautions were necessary to protect babies.

Despite those measures, she described a calm hospital environment. “Everything was as usual,” she told CNN. “Everyone was wearing masks, that’s all.”

Other residents questioned whether officials were being transparent, while a woman identified only as Ekaterina said daily life appeared unchanged. She said some acquaintances were “slightly panicking,” but added, “Everything is as usual, no visible changes.”

Local media reported that 60 employees at the Irkutsk Research Anti-Plague Institute were quarantined and that several hospitals faced restrictions. The Kremlin urged the public to trust Rospotrebnadzor rather than “various rumors and speculation,” although the watchdog released limited information.

US Secretary of State Marco Rubio called on Russia to provide more details. “I think it’s incumbent upon Russia to obviously share more information with the world,” he said. “Maybe it’s bigger than we thought. We don’t know, but I think it would be reckless at this moment, given the limited information we still have, to speculate.”

The United States formally requested information, while President Donald Trump said he expected to speak with Russian President Vladimir Putin. Kremlin spokesman Dmitry Peskov said no call had been arranged but that one could be organized if requested.

The World Health Organization said it was communicating with Russian authorities to “verify the event, its circumstances, the laboratory tests underway, and their results.” It assessed the public health risk to the general population as low based on unofficial information.

WHO chief Tedros Adhanom Ghebreyesus said Russian authorities reported that no plague case had recently been registered in the Irkutsk region. He said contacts had been identified, tested and medically observed, with no high threat pathogens detected, while WHO continued seeking clarification about reports of a second employee with pneumonia of undetermined cause.

Kazakhstan, Kyrgyzstan, Uzbekistan and Tajikistan introduced quarantine controls at border crossings, and Uzbekistan increased official readiness for highly infectious diseases. No additional Chinese border measures were apparent, and flight tracking data reviewed by CNN showed no recent cancellations between Irkutsk and China.