A laboratory worker in a plague research institute in Siberia died last week after developing pneumonia. Since then, local reports suggesting that she broke a test tube containing plague bacteria have fueled speculation about how she became ill. Russian authorities disputed that account and told the World Health Organization (WHO) that plague had not been detected in her tests nor in those of her close contacts. 

At the same time, Russian authorities have reportedly quarantined as many as 200 people, which public-health experts say would be an unusual response to an isolated case of pneumonia. On Tuesday evening, the WHO asked Russia for more information following media reports of a second case of pneumonia of unknown cause.

Researchers who work in public-health policy and infectious diseases have been watching this rapidly evolving and opaque situation with concern. Here’s what worries them. 

This doesn’t look like the average lab accident

The pattern of events doesn’t fit neatly with the explanation that a lab accident with a known bacterium sickened the worker, says Jennifer Nuzzo, director of the Pandemic Center at the Brown University School of Public Health. In labs that study Yersinia pestis, the bacterium that causes plague, protocols are in place to deal with accidental exposure. Wearing personal protective equipment and working under a fume hood provides some protection. But if someone finds they’ve been exposed, they would take antibiotics, which is an effective treatment for naturally occurring plaque bacteria. “You’d be fine. You don’t die, typically,” says Nuzzo. A lab exposure “would be a regrettable accident that sometimes occurs.” 

That seems out of sync with the substantial response on the part of Russian authorities. “The magnitude and severity of that response is also worth looking at,” she says, referring to reports that up to 200 people are under observation and that local hospitals have been closed. “Now, that could just be bureaucratic reflexes. But I would feel more confident in what was going on if I knew specifically what she was tested for and what came back negative.” By this time, Nuzzo continues, “they should have a full sequence”—meaning the pathogen that killed the lab worker should be identified. 

Much is unknown about the situation, and some experts have said it’s worth considering the possibility that an engineered pathogen, rather than a naturally occurring one, could be involved. Dr. Ashish K. Jha, who coordinated the White House’s COVID response under President Joe Biden, wrote on X on Oct. 4 that “an accidental release from a deliberate program” was a scenario he had long worried about. Russia has a long history of bioengineering pathogens. After the fall of the Soviet Union, that nation’s programs were officially shuttered, but the current situation is unclear. 

“You can’t help but worry that there is something more here than meets the eye,” Jha tells TIME. “What I will say from my conversations with friends in the [Trump] Administration is that they’ve been very worried about this…[But] they’re not getting a lot of information and data.”

”I’m going to say something that’s going to sound incredibly naive, but I’ll say it: What I hope is that the Russians will be very forthcoming and transparent about what was going on in this lab, but one can imagine that they may not be,” Jha says. 

“If it’s plague, breathe a sigh of relief, because we know what to do about plague,” says Nuzzo. “We have a clear solution…The worry is it’s not that, it is something different, something for which we don’t have easy solutions.”

Are we prepared for an outbreak of a new pathogen?

No, Nuzzo and Jha agree. We are in a worse situation now compared to pre-COVID times, Nuzzo says. “The protections we had in 2019, early 2020–there are now fewer of them, and we are more vulnerable now than we were then,” Nuzzo says, pointing to reduced monitoring and less information flow between countries. “This is why countries need to fund and maintain overseas scientific engagements, because then they know the actors, they know their motivations, they know what’s normal. It’s also why you want to have a strong, capable, and relied-upon WHO, because sometimes they’re the best entity to have the conversations to surface the information.” 

Jha also flags the lack of monitoring: “The biggest weakness we have is we have almost no biodetection system in our own country.” If someone in Siberia was infected, got on a plane, and flew to New York City, “we would not know. We just need a much better global monitoring system on this.” 

Jha and a colleague from the Biden White House, Nikki Romanik, have started a public benefit corporation to build a monitoring system that draws on search and social media information, clinical information from hospitals, and wastewater sequencing. Wastewater monitoring typically looks for hand-picked pathogens, such as RSV or COVID-19. “Our strategy is you flip it, you sequence everything in the wastewater and you look for anything that doesn’t belong. That’s how we would detect it,” he says. The system, called BioRadar, is currently being tested in Dallas. 

It’s unlikely that the pathogen that caused the lab worker’s death—if it does turn out to be something new—would spread as effectively as COVID did, says Jha. Still, “a lot of the capabilities that I spearheaded building when I was at the White House for preparation for future outbreaks have been dismantled by U.S. Health and Human Services Secretary Robert F. Kennedy. A lot of stuff has been pulled back and taken away. We had put together a whole respiratory virus vaccine program called Project Next Gen that was taken down. We don’t have mRNA vaccine platform funding anymore because of Secretary Kennedy. We are not nearly as ready as we need to be.”

What if it turns out to be nothing? 

There is still the possibility that in the end, “this whole thing could be just a lot of coincidence and overreaction,” says Nuzzo. “And then people are going to be like, ‘You got us all whipped up about this thing.’ I am here to say, we have no idea. This could be nothing. But when your fire alarm goes off, you don’t get mad at it for going off when nothing happened. You’re glad nothing happened.” Ultimately, there could be real threats in our future, and the key is to be prepared, she says.

Jha views the situation as a wake-up call to Americans. “Continue to pay attention, because that is important. Secondly, push our political leaders to get much more proactive. Because the truth is, you don’t want to get concerned after the outbreak has happened. You want to be concerned before, and build the systems you need to make sure that we are ready for the next one,” he says.

“Without sounding like an alarmist, look at what has happened in the last six months alone. There was the hantavirus outbreak on the cruise ship, and we’re hearing from [AI company] Anthropic about all these people who are starting to use AI models to build biological weapons,” Jha says. “There’s been this massive proliferation of high-risk labs around the world in the last five years, and so even if this one incident turns out to be not that big a deal, I am very worried we’re going to see more and more things like this—and one of them will be a big deal.”