Hantavirus: the disease you wish you’d never heard of, as visions of the Covid pandemic flash through your head. I’ve seen lots of breathless coverage and some bizarre takes on social media, so I imagine many people are confused as to what’s going on.

Let me start by saying that this isn’t the Covid pandemic – only Covid was Covid. Previous hantavirus outbreaks have been contained (although none were on a cruise ship). So, for now, the risk to the general public is low – colleagues and I are still carrying on as normal and watching to see whether new infections arise outside the original cruise ship group. Those new infections would be the key step-change determining whether we see further spread and higher-risk public health alerts – or whether we’re at the end of this outbreak.

The first thing to know is that hantavirus outbreaks happen all the time across the world. You just don’t hear about them. In fact, you probably didn’t hear about the Andes strain hantavirus outbreak in 2018 in Argentina, with 34 confirmed cases and 11 deaths.

Part of what makes the current outbreak unique – and newsworthy – is it being on a cruise ship with about 150 people of 23 nationalities. Cruise ships are notorious for making outbreak control difficult, given the close living conditions, the frequent stops in various ports, the globetrotting nature of passengers and the difficulty in managing a public health response on the ship once a virus is detected.

Do you keep everyone on the ship, with the risk that further people become infected and unwell? Or do you take people off the ship and risk spread in each of their home nations? In this instance, quite a few passengers disembarked before the outbreak was detected and took commercial flights back home, meaning there is already wider potential exposure to the virus. We’ll only know for sure in the weeks to come.

When hantavirus was first mentioned, public health experts were hoping it was any strain beside the Andes strain, which can transmit from human to human and has previously caused super-spreading events. Add to that the fact that it has an incubation period of one to eight weeks, which means that just because someone tests negative today, it doesn’t mean they’re not infected. They could still become symptomatic and infectious later.