Prof Piero Olliaro, Professor of Poverty-Related Infectious Diseases and Director of Science, ISARIC, Pandemic Sciences Institute, University of Oxford, said:
“Information about the reported incident in Siberia remains incomplete and, in some respects, contradictory, so it is too early to draw firm conclusions about what has happened or the level of risk.
“What we know in general from the science and history of this bacterium, is that Pneumonic plague is rare compared with the more common bubonic form of plague. It can be transmitted through inhalation of respiratory droplets from a person with pneumonic plague, or through exposure to infected materials such as bodily fluids or tissues, etc., which may include exposure in a lab. Symptoms generally appear very quickly, within one or two days, and if untreated or inadequately treated it is very often fatal.
“Importantly, plague is treatable with commonly available antibiotics, particularly when it is recognised and treated early. Through ISARIC, we have worked with colleagues in Madagascar since 2018 on the first conclusive clinical trial of treatments for bubonic plague, which demonstrated that effective antibiotic regimens are available. During this work, we have also encountered and treated cases of pneumonic plague.
“Plague itself has not disappeared: the bacterium that causes it, Yersinia pestis, persists in animal reservoirs across many parts of the world. Around 200 rodent species can harbour the bacterium, with reservoirs found across the Americas, Eurasia and Africa. Sporadic human cases therefore continue to occur, but established surveillance, infection-control measures and effective antibiotic treatment are important tools for limiting their impact.”
Dr Malick Gibani, Clinical Associate Professor in Bacterial Vaccinology, Imperial College London, said:
What is the wider risk, how common/uncommon this is, precautionary measures, etc.
“Based on the information we know, it seems as though this is a precautionary measure albeit one with high consequences. If a researcher has come into is working in the laboratory that handles plague, and has developed an illness that could be compatible with plague, then it appears that measures are being implemented to quarantine any potential contacts and prevent any onward transmission.
“Firstly, I haven't seen any information that this is a microbiologically confirmed case, but given the potential exposure risk, then the screening and/or quarantining potential contacts appears proportionate. At the time of writing, I'm not aware of any suspected secondary cases, but clearly this will (hopefully) emerge with time.
“On the wider risk, plague is something we all know about, but it isn't just of historical interest. There are a few hundred cases of plague reported each year globally usually in geographically restricted areas, particularly in Madagascar and the Democratic Republic of Congo - although there are a small number of cases in the Western United States, Central Asia, Mongolia, etc. Whilst the crude overall number of cases is low, there is a large zoonotic animal reservoir and there is therefore always a theoretical risk of zoonotic spillover.”
Should we be concerned? What are the proper protocols when a lab worker like this dies of “pneumonia of unknown aetiology”?
“It is difficult to comment with confidence given the relatively limited information currently available. Based on reports, there appears to be a suspected index case and contacts have been quarantined. If there is an exposure in a laboratory to a potentially dangerous pathogen, the usual procedure would be to undertake a risk assessment of who may have been exposed and the nature of their contact. People considered at risk can then be monitored and, where appropriate, screening, quarantine, or post-exposure prophylaxis with antibiotics may be offered.”
Should we be concerned?
“I think it's important that we see how this pans out, and ideally, there'd be good communication between the public health authorities and the wider global health community.
“I think this emphasises the need to be aware of ongoing outbreaks of serious bacterial pathogens and highlights the need for investment in biosecurity, particularly for preventing biological risks. This could include developing medical countermeasures like better diagnostics or vaccines.”
There are reports of 200 lab workers being monitored -- would that be normal?
“Whether this is a hight number is difficult to judge without more detail. In the event of a potential laboratory exposure, it would be normal to identify individuals who might have been exposed and to monitor them according to the assessed level of risk. The scale of any monitoring programme would depend on the circumstances of the exposure and the number of people potentially affected. If the reports are to be believed, there may be a lab worker who's been exposed to the Yersinia pestis bacteria. If that's the case, it would be reasonable to take precautions for anyone they've been in contact with.”
How rare and how dangerous is pneumonic plague? Can it be treated?
“Pneumonic plague is a very severe manifestation of plague disease. Some textbooks will say it has 100% mortality if left untreated historical data, and it's difficult to have accurate figures in the modern age. It is treatable with antibiotics, particularly if started early. That's why anyone with high-risk potential exposure might be offered post-exposure prophylaxis with antibiotics and/or quarantine.
“Classically, plague is said to present in different forms - i) bubonic plague, which most of us learned about in school, usually presents with fever and swollen necrotic lymph nodes and is typically associated with flea bites; ii) septicaemic plague, when the infection enters the bloodstream and patients develop a severe systemic illness and iii) pneumonic plague, when the infection affects the lungs, often following spread through the blood. Pneumonic plague is of particular concern because it can be transmitted from person to person unlike bubonic plague. I’ve read different estimates of transmissibility vary considerably depending on the setting (Ro something like 1.3 - 3, depending on where you read), but it is recognised as a potentially serious public health threat if not rapidly identified and controlled.”
Why would a laboratory be working with it?
“There are entirely legitimate scientific and public health reasons. As you can imagine, there is a lot of investment in biosecurity at the moment. Several labs around the world work on plague to understand more about how it causes disease and to develop new vaccines, treatments, etc. I wouldn't really like to speculate about this case based on the information we currently have available.”
Prof Brendan Wren, Professor of Microbial Pathogenesis, London School of Hygiene & Tropical Medicine (LSHTM), said:
What is the wider risk, how common/uncommon this is, precautionary measures, etc.
“Potentially this lab acquired case of pneumonic plague could be transmitted by the respiratory route. Yersinia pestis, the causative bacterium of plague, is fairly transmissible, but not as transmissible as SARS2/COVID.”
Should we be concerned? What are the proper protocols when a lab worker like this dies of “pneumonia of unknown aetiology”?
“Plague is still endemic in many parts the world, including western parts of the US, so there shouldn’t be too much concern as the transmission of Yersinia pestis between humans is generally poor.”
There are reports of 200 lab workers being monitored -- would that be normal?
“Isolation and monitoring are sensible strategies.”
How rare and how dangerous is pneumonic plague? Can it be treated?
“There are still around 2000 cases of plague each year that are treatable with standard antibiotics. But there are multi-antibiotic-resistant strains emerging, and if the laboratory is working on such a strain, then treatment options may be limited.”
Why would a laboratory be working with it?
“Generally, to make improved vaccines that could be used in regions of the world where plague is endemic. If Yersinia pestis was weaponised, a vaccine for military personnel may be desirable.”
Prof Alice Hughes, Professor Conservation Science, University of Melbourne, said:
“It's important to note that bubonic plague breaks out regularly in Northern Asia (almost annually). Whilst bubonic plague is easy to treat, it can become pneumonic if left untreated. Pneumonic plague has higher mortality and is more contagious, however the incubation is typically only 1-3 days, and as yet no one has shown symptoms.
“As people are unlikely to catch it from wildlife, the contagion was in a lab (and has presumably well disinfected) and people were rapidly quarantined, it is highly unlikely that it will spread further- and thus, whilst it is contagious, it is unlikely to have the opportunity to spread.”
Dr Zania Stamataki, Associate Professor of Viral Immunology, Academic Lead for Containment Level 3 Laboratories, University of Birmingham, said:
“The death of a fellow laboratory scientist in Irkutsk is a terrible loss, and my thoughts are with her family and her colleagues.
“On the cause, it is so far described as a pneumonia of unknown origin, and Yersinia pestis has not been confirmed as the cause of pneumonic plague.
“I understand why people find the idea of plague in a laboratory alarming, so it is worth saying why that work exists. Plague is not a historical disease. It remains endemic in rodent populations across Africa, Asia and the Americas, and human cases occur every year, including outbreaks of the pneumonic form. Diagnostics, vaccine development and surveillance for antibiotic resistance all require laboratories that hold and study the live organism. This work is vital to prepare against outbreaks.
“In the UK Yersinia pestis work is governed by two separate systems. The first is safety. Y. pestis is a Hazard Group 3 agent, so handling the viable organism is done at Containment Level 3: negative-pressure airflow, HEPA-filtered extract, a room that can be sealed and fumigated, and all open manipulation inside a microbiological safety cabinet. The Health and Safety Executive must be notified before such a facility is used and inspects it thereafter.
“The second is security. Y. pestis is a Schedule 5 agent under the Anti-terrorism, Crime and Security Act 2001. We must notify the authorities of what we hold, store it under lock, maintain a named list of everyone with access, and satisfy Counter Terrorism Security Advisers from the police.
“Those controls work, which is why laboratory-acquired infections with this organism are rare. They are not impossible, and this is why an incident warrants a full account of what happened. That account matters beyond Russia. Around 200 contacts are reportedly under observation, and plague responds well to antibiotics if treatment starts early. Early notification allows effective treatment and outbreak containment.”
Prof Ian Jones, Professor of Virology, University of Reading, said:
“This case here seems like a rare lab accident and is unlikely to go much further. Although it is true that pneumonic plague is directly transmissible, the contacts of the primary case are known and can be treated if they show any sign of infection. Plague carries a huge history and is still present in many parts of the world including Russia, but the living conditions associated with previously spread are no longer generally true, antibiotics are available and its potential is therefore limited.”
Dr Simon Clarke, Associate Professor in Cellular Microbiology & Public Engagement in Science, University of Reading, said:
“Reports from Russia have inevitably drawn comparisons with Covid-19, but it is important to remember that pneumonic plague is a very different disease. It is caused by bacteria, Yersinia pestis, famous for causing the Black Death, that remains with us today mostly in animals across parts of Asia, Africa, and the Americas.
"Pneumonic plague is particularly serious because it means the infection has reached the lungs and is nearly always fatal if not treated promptly. Unlike the bubonic plague which enters the body via infected flea bites, pneumonic plague can spread between people through respiratory droplets during close contact.
"Unlike many viral respiratory diseases, plague is caused by bacteria and antibiotics such as fluoroquinolones and aminoglycosides work well against this pathogen if administered early enough and are often given prophylactically, post-exposure.
"One claim attracting attention is that a laboratory worker may have been infected after breaking a test tube in the lab. It is not unheard of for pathogens to escape from labs, but an awful lot must have gone wrong for a lab worker to be infected by a broken test tube.
"Having worked in high-containment laboratories, I know that handling dangerous pathogens involves multiple layers of protection, strict procedures, safety cabinets, airflow systems and careful procedures carried out by well-trained staff. Lab-acquired infections are rare events, and a broken tube would not automatically lead to exposure or infection. We also don't tend to use test tubes very much.
"Until more details emerge, it is difficult to assess whether this represents an isolated case, an occupational exposure, or evidence of wider transmission. Exactly why this lab was working with this pathogen remains to be understood, but it is present in wild animals, and it could have come from a surveillance study.
"Any outbreak of plague is worrying, but this can be controlled and stopped with appropriate surveillance and control measures. Transparency, rapid diagnosis, and effective contact tracing will be the most important factors in managing this outbreak.”
Declared interests
Prof Piero Olliaro: “I can confirm there’s no conflict of interest.”
Dr Malick Gibani: “No declarations of interest relevant to this. I have had previous paid non-promotional speaking engagements for GSK related to vaccines for antimicrobial resistance.”
Prof Brendan Wren: “I have no conflicts of interest in making my statements below.”
Prof Alice Hughes: “No DOI”
Dr Zania Stamataki: “I have no conflict to declare as I don’t work on this pathogen.”
Prof Ian Jones: “I declare no conflicts of interest”
Dr Simon Clarke: “I have no declarations to make.” | 
