Case report: Up to 80% of COVID-19 infections are asymptomatic

The ship was not allowed to re-dock in Argentina after the country closed its borders, so it continued on to Uruguay, where eight people were evacuated to a hospital. Uruguayan officials eventually arranged for everyone remaining on board to get tested before the boat docked.

Out of 217 people on board, 128 tested positive for COVID-19—but only 24 of those people showed symptoms prior to testing. The remaining 104 people—81% of those who tested positive—had not experienced any symptoms, the researchers report…

It’s difficult to extrapolate the results to larger populations, since the people on board the ship were living in close quarters while entirely isolated from outside life for about a month. Even still, the results are a stark reminder of how likely COVID-19 is to spread within communities, and how difficult it can be to tell when it does.