The study, published in the journal Lancet Global Health, estimates that 1.7 billion people, or 22 percent of the world population, have at least one underlying condition that poses a higher risk of serious complications of covid-19.

However, it varies very much in terms of age. For people younger than 20 years, less than 5 percent have a higher risk, while 66 percent of those 70 years and older have it.

4 percent may need hospital care

349 million people, which corresponds to 4 percent of the world's population, are at risk of becoming so ill that hospital care is required. 

Among them, age is also important. Less than one percent of those younger than 20 years run this risk while 20 percent of those older than 70 years run the same risk.

The underlying diseases that affect the risk most are chronic kidney disease, diabetes, cardiovascular disease and chronic respiratory disease.

"Meaningless number exercise"

Agnes Wold, professor of clinical bacteriology at the University of Gothenburg, is critical. She believes that the information from the study becomes "fairly meaningless". The large group of people, who are not older, run such a low risk of becoming seriously ill in covid-19 that an increase in the risk due to underlying disease does not mean much.

- It's the age that matters. There is no other risk factor that comes close to it, says Wold.

- It's pointless number exercise. I'm not saying the numbers are wrong but the context is completely wrong. It's so trite. We have known since China that it is the age that is by far the biggest risk factor.

"Don't want to cure the disease"

The Lancet study included UN data on underlying diseases in 188 different countries. Agnes Wold believes that there is a lot of difference between different countries, which makes the study's conclusions uninteresting to interpret.