The study, which analyzed data of those with underlying medical condition by sex, age and group in 188 countries, was published in the peer-reviewed, Lancet Global Health journal.
The authors, Medical Xpress reports, based their estimates on the 2017 disease prevalence data from the Global Burden of Diseases, Injuries and Risk Factors Study, United Nation population estimates for 2020, and the list of underlying health conditions relevant to COVID-19, as defined by current guidelines.
It notes that the study provides global, regional and national estimates for the number of people with underlying health conditions.
Based on guidelines by the World Health Organization and public health agencies, risk factors for severe COVID-19 include; cardiovascular disease, chronic kidney disease, diabetes and chronic respiratory disease.
The authors explained that they focused on underlying chronic conditions and did not include other possible risk factors not yet included in all guidelines, such as ethnicity and socioeconomic deprivation.
They concluded that their estimates are, therefore, unlikely to be exhaustive, but serves as a starting point for policy-makers.
The researchers also said the GBD prevalence estimates are likely to be higher than those from national databases because they are designed to capture cases that might be undiagnosed or not severe enough to be included in electronic health records.
“As countries move out of lock-down, governments are looking for ways to protect the most vulnerable from a virus that is still circulating.
“We hope our estimates will provide useful starting points for designing measures to protect those at increased risk of severe disease.
“This might involve advising people with underlying conditions to adopt social distancing measures appropriate to their level of risk, or prioritizing them for vaccination in the future,” says one of the authors, Andrew Clark, an associate professor, from the London School of Hygiene & Tropical Medicine, UK.
The study notes that although the estimates provide an idea of the number of people governments should prioritize for protective measures, not all individuals with these conditions would go on to develop severe symptoms if infected.
It further estimates that 4 per cent of the world’s population, about 349 million of 7.8 billion people, would require hospitalization if infected, suggesting that the increased risk of severe COVID-19 could be quite modest for many with underlying conditions.
To help determine the degree of increased risk, Medical Xpress notes that the researchers provided separate estimates of the proportion of those with and underlying ailments, who would require hospitalization if infected.
This, they did by calculating those at high risk, using infection hospitalization ratios for COVID-19 and made adjustments for differences between countries.
“Countries and regions with younger populations have fewer people with at least one underlying health condition, while those with older populations have more people with at least one condition.
“For example, the proportion of the population with one or more health condition ranges from 16% in Africa (283 million people out of 1.3 billion) to 31% in Europe (231 million out of 747 million),” the study states.
However, Associate Professor Clark cautions that the evidence needs to be carefully communicated to avoid complacency about risk in Africa.
“The share of the population at increased risk of severe COVID-19 is generally lower in Africa than elsewhere due to much younger country populations, but a much higher proportion of severe cases could be fatal in Africa than elsewhere,” he said.
Medical Xpress notes that globally, it is estimated that less than 5 per cent of those under 20 and 66 per cent of those above 70, have at least one underlying condition that could escalate their COVID-19 infection.
While among the working-age population, 15 to 64 years – 23 per cent, are estimated to have at least one underlying condition, with males assumed to be more likely to require hospitalization if infected.
The authors also estimate that 349 million people worldwide are at high risk of severe COVID-19, meaning they would require hospital if infected.
“This risk varies from less than 1% of people under 20 to nearly 20% of those aged 70 or older, rising to more than 25% in males over 70.
“In all age groups under 65, around twice the number of men as women would require hospitalization.
“Above 65 years, the ratio becomes less marked because women are over-represented in older age groups due to longer life expectancy.
“Our estimates suggest that age-based thresholds for shielding could play a role in reducing deaths and reducing the number of people who require hospital treatment, but the choice of threshold needs to be balanced against the proportion of people of working age affected, as well as the health and economic consequences that might be associated with long periods of isolation,” says an author, Dr. Rosalind Eggo.
Commenting, Professor Nina Schwalbe, from Columbia University Mailman School of Public Health, USA, says:
“An increased understanding of risk factors, including the effects of social determinants and their interplay, provides an opportunity to target mitigation strategies and helps to allay the popular misconception that everyone is at equal risk of severe illness.
“As the authors note, it is time to evolve from a one-size-fits-all approach to one that centers on those most at risk.
“This will need to happen at both the individual and community level. Considering the relevance of social determinants.
“Such an approach requires urgently improving communication about COVID-19; increasing access to health services, including palliative care, for those already socially vulnerable; and providing economic support to cope with the mitigation,” said Prof. Schwalbe.
By Sally Ahmed