Close confines help the virus to spread, but closed environments are also an ideal place to study how the new coronavirus behaves.
When COVID-19 was detected among passengers on the cruise ship Diamond Princess, the vessel offered a rare opportunity to understand features of the new coronavirus that are hard to investigate in the wider population. Some of the first studies from the ship — where some 700 people were infected — have revealed how easily the virus spreads, provided estimates of the disease’s severity and allowed researchers to investigate the share of infections with no symptoms.
Information gleaned from such outbreaks is crucial for people making decisions on how to manage the epidemic, say researchers.
“Cruise ships are like an ideal experiment of a closed population. You know exactly who is there and at risk and you can measure everyone,” says John Ioannidis, an epidemiologist at Stanford University in California. This is very different from trying to study the spread in a wider population, where only some people, typically those with severe symptoms, are tested and monitored.