We all run the risk of falling ill with Covid-19, but some are more at risk than others. From the beginning of the pandemic, in fact, it has been evident that people suffering from previous diseases are more likely to encounter serious forms of disease, so much so that the World Health Organisation (WHO) and also some national health agencies have formulated guidelines listing risk factors.

But how many are these people? Researchers from the London School of Hygiene & Tropical Medicine tried to answer this question, drawing on WHO, UN and national databases, they concluded that about 4% of the world population would require admission to hospital if they get the new coronavirus and identified the categories from which to design measures of prevention by region.

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The approach

Cardiovascular disease , chronic kidney disease, diabetes and chronic respiratory disease are some of the conditions that WHO and other public health agencies have identified as risk factors for the development of severe forms of Covid-19 .

Starting from the data on the prevalence of these conditions contained in the national databases and in the WHO Global Burden of Diseases, Injuries and Risk Factors Study 2017 , and from the UN estimates, in the new study published in Lancet Global Health , London researchers School of Hygiene & Tropical Medicine provide estimates global, regional and national of the number of people that would require an admission to hospital should get sick of Covid-19. The analysis includes 188 countries, highlighting their differences in relation to the composition of the population and the main public health issues of each, as well as distinguishing by age group and gender.

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World estimates

What emerged is that there would be 1.7 billion people in the world (22% of the world’s population) suffering from at least one chronic health condition indicated by WHO’s Covid-19 guidelines. In particular, less than 5% of people under the age of 20, but over 66% of people aged 70 and over , have at least one basic condition that could increase the risk of severe forms of Covid-19. Among the working-age population (15 to 64 years), it is estimated that 23% have at least one basic condition.

Not all, however, according to the researchers, would develop serious forms of the disease if they became infected, but estimate that to request hospitalisation would be roughly 349 million people, or 4% of the world population. The risk ranges from less than 1% in people under 20 years of age to almost 20% in those aged 70 and over, and rises to over 25% in males over 70 years of age. In all age groups under 65, about double the number of men compared to women would require hospitalisation. Over 65, the relationship becomes less pronounced because women are over represented in the older age groups due to higher life expectancy.

Country by country

It goes without saying that based on the composition of the population there are differences between countries. In Africa, for example, the average age of the population is much lower than in Europe, and in fact the percentage of the population with one or more health conditions varies from 16% in Africa (283 million people out of 1.3 billion) 31% in Europe (231 million out of 747 million). This does not mean, however, that Sars-Cov-2 is not a problem for the African continent, where, especially in certain states, AIDS is a real scourge.

Other countries where the average age of the population is lower also suffer from specific public health problems , such as in the case of Fiji and Mauritius where there is a high prevalence of diabetes.

The limits

The study certainly has limitations, the authors admit. The estimates, in fact, have been obtained by taking into consideration the chronic risk factors included in the international guidelines, but do not take into account other conditions that could influence such as ethnicity and socio-economic conditions. For this reason, the figures are indicative and serve as a starting point for the decisions of policy makers, who could activate consultancy services for the categories most at risk or draw up prevention plans appropriate to the level of risk, giving priority to vaccination campaigns in the future.

“As countries exit the lockdown, governments are looking for ways to protect the most vulnerable from a virus that is still around,” said Andrew Clark. ” We hope that our estimates provide useful starting points for designing measures to protect those who have an increased risk of becoming seriously ill .