A new Swedish study found that just 7% of people in Stockholm had caught the novel coronavirus COVID-19 by the end of April.
According to Business Insider, Swedish forecasters had previously predicted up to half the population would catch the virus by May.
However, epidemiologists say at least 60% of people need to catch the virus before any protective immunity can be achieved.
Sweden has not implemented strict, wholesale lockdown measures in response to the coronavirus pandemic.
Instead, the country has largely allowed businesses to remain open and students to attend school.
Sweden this week overtook the UK, Italy, and others to become the country with the highest number of coronavirus deaths per capita.
Professor Tom Britton helped devise the model Sweden's public health agency is using.
It's surprising the forecasts are so wrong.
Professor Tom Britton