The death of a lab worker in Irkutsk has prompted fresh questions over Russia's handling of outbreak information. The episode echoes a long record of delayed disclosures during epidemics, accidents and national emergencies.

The Kremlin has long faced criticism for secrecy in the way it handles public information, especially on accidents, outbreaks and other emergencies. The suspicious death last week of a worker at a research lab in Siberia has again raised questions about how Moscow controls the official narrative, with unconfirmed reports in Russia linking the case to suspected pneumonic plague.

Russia's public health watchdog, Rospotrebnadzor, told the World Health Organisation that no case of plague has beened in the Irkutsk region of southeastern Siberia. In brief statements, the agency said the lab worker had pneumonia of an "unknown" origin and that tests found no evidence that her illness was caused by any of the pathogens she handled at the Irkutsk Anti-Plague Research Institute of Siberia and the Far East. The WHO has asked Russia to share more information on the cause of the severe pneumonia, the pathogen that led to public health measures, and media reports that a second employee also had pneumonia of undetermined cause.

The limited official information around the worker's death follows a pattern seen in earlier Soviet and Russian responses to infectious disease outbreaks, accidents and emergencies, where key details were often withheld for years.

One of the earliest examples came in the winter of 1959-60, when Soviet graphic artist Alexei Kokorekin fell ill and died soon after returning from India. Doctors at first struggled to identify the cause as smallpox, a disease thought to have been eradicated decades earlier. Once they confirmed it, the authorities mounted a huge containment effort. The KGB traced Kokorekin's contacts, thousands of people were isolated, and an Aeroflot flight carrying one of his contacts was told to turn back to Moscow before landing in Paris.

Travel to and from Moscow was halted, and thousands of vaccination teams gave shots to millions of people in the capital and nearby areas. International media reported the campaign, but Soviet state media did not. The outbreak caused 46 confirmed cases and three deaths in Moscow before it was brought under control in 44 days. Its full details did not become public until the final years of the Soviet Union.

Another smallpox outbreak followed in August 1971 during tests of a smallpox bioweapon on Vozrozhdeniya Island in the Aral Sea. A research ship sailed too close to an aerosolised plume of microbes, and a marine biologist on board contracted smallpox. She then spread it to several others in the town of Aralsk, in what is now Kazakhstan, leading to 10 infections and three deaths. The town was quarantined and more than 40,000 people were vaccinated within days, but the public was not told what had happened. The incident only became widely known in 2002, when US researchers publicised old Soviet archives.

On April 2, 1979, anthrax spores were accidentally released from a secret biological weapons laboratory in Sverdlovsk, now Yekaterinburg, in the Ural Mountains. The leak happened after a worker failed to replace a faulty ventilation filter. At least 68 people died in the outbreak that followed. Soviet authorities blamed the deaths on contaminated meat sold at a street market, while the KGB confiscated medical records and kept details of the accident hidden. The truth emerged only after the Soviet Union collapsed in 1991, under Russian President Boris Yeltsin, who had earlier been the Communist Party chief in Sverdlovsk.

The 1986 Chernobyl nuclear disaster became another defining case. When reactor No. 4 exploded at the Chernobyl nuclear power plant in Soviet Ukraine on April 26, it sent a radioactive cloud across Europe. The authorities were slow to report the accident or warn the public. After Sweden detected the radiation, Moscow at first denied that any accident had taken place. Officials waited 36 hours before evacuating the town of Pripyat near the plant. Five days later, tens of thousands of people marched in Kyiv's May Day parade despite exposure to radioactive fallout.

Even under Soviet leader Mikhail Gorbachev's policy of "glasnost", or greater openness, the authorities heavily censored medical data and casualty figures. Thirty plant workers and firefighters died soon after the accident from acute radiation sickness, and thousands more later died from radiation-related illnesses.

Questions over official transparency also resurfaced during the COVID-19 pandemic. Independent Russian outlets and international media reported that the death toll could be far higher than official figures suggested, pointing to a sharp rise in overall mortality. Russian authorities rejected those reports as part of a Western disinformation campaign. Officials said the relatively low death toll reflected an early travel ban on China, quick restrictions and wide testing that helped detect infections and stop cases from becoming life-threatening.

The authorities also denied reports of widespread shortages of personal protective equipment and poor infection control practices in dozens of hospitals. Some medical workers said they were threatened with dismissal or even prosecution for speaking out. In 2020, Russia criminalised "false information" about threats to public safety, and human rights groups said dozens of people were prosecuted for allegedly making fake claims. By the end of that year, however, officials effectively conceded that the death toll was several times higher than previously reported.

In early 2022, Russian authorities said the country had recorded more than 13.5 million confirmed COVID-19 cases and 338,091 deaths, the highest death toll in Europe at the time. Russia's state statistics agency Rosstat, which uses broader counting criteria, said there were 681,100 virus-linked deaths between April 2020 and December 2021. "The system can silence, but it's not competent enough to coordinate, so it produces contradiction instead of a unified false account," Judy Twigg, a professor of political science at Virginia Commonwealth University, said in written comments this week.

From the latest lab death in Siberia to earlier outbreaks, industrial disasters and the pandemic, the record shows repeated instances in which official information in Russia was delayed, restricted or contradicted by later disclosures.