Medscape

Becvky McCall

Gerry Gajadharsingh writes:

“What I would have written was that 80% of people are at minimal risk of severe COVID 19! Talk about making people stressed, I think we now need to focus on the need to get back to a functioning society and economy.

 As lockdown begins to slowly unwind, it’s important to remember that the majority of the population will continue to be at low risk of developing severe symptoms of COVID 19 if they catch SARS-CoV-2 the novel coronavirus. However, there is still a group of people, the research below suggests 20% with underlying health conditions, that still need to be very careful regarding their social distancing and infection.

 Using data from 188 countries, the team from the London School of Hygiene & Tropical Medicine (LSHTM) led by Andrew Clark, PhD, developed models to determine the most at risk groups and analysed the number of people with an underlying condition by age group, sex and country.

Dr Clark and colleagues find that there is wide variation in risk, ranging from less than 1% of people under 20 years to nearly 20% of those aged 70 plus (25% in men over 70).”

Around 1 in 5 people worldwide (1.7 billion) have an underlying health condition that makes them more prone to severe COVID-19, according to results of a global modelling study. The researchers also determine age-based thresholds for risk.

Knowing which groups are most vulnerable could inform policymakers in prioritising where to employ measures to protect vulnerable people, and reduce pressure on health systems, note the authors in the work published in the June 15thedition of The Lancet Global Health.

Risk Modelling

Using data from 188 countries, the team from the London School of Hygiene & Tropical Medicine (LSHTM) led by Andrew Clark, PhD, developed models to determine the most at risk groups and analysed the number of people with an underlying condition by age group, sex and country.

The analysis estimates that 349 million people worldwide are at high risk of severe COVID-19 which would require hospitalisation. Dr Clark and colleagues find that there is wide variation in risk, ranging from less than 1% of people under 20 years to nearly 20% of those aged 70 plus (25% in men over 70).

“Our estimates are uncertain and focus on underlying conditions rather than other risk factors such as ethnicity, socioeconomic deprivation, and obesity, but provide a starting point for considering the number of individuals that might need to be shielded or vaccinated as the global pandemic unfolds,” write the authors.

They add that while the analysis provides numbers of people who could benefit from shielding due to underlying conditions, in practice, because of low diagnosis of chronic conditions in low-income settings, “age-based thresholds could play a key role”. However, they add that the choice of age threshold needs to be carefully balanced against the proportion of the working age population affected and the adverse mental health consequences that might be associated with long periods of isolation.

Loosening Lockdowns

The work is particularly important given the discussions by national governments worldwide around how to lift lockdown with respect to protecting members of society who are most vulnerable to severe COVID-19 infection, whilst also lifting lockdown measures to get economies moving again.

The work is particularly important given the discussions by national governments worldwide around how to lift lockdown with respect to protecting the members of society who are most vulnerable to severe COVID-19 infection, whilst also lifting lockdown measures to get economies moving again.

Essentially, the groups at highest risk, ie, with at least one underlying health condition relevant to COVID-19, include people in countries with ageing populations, African countries with high HIV/AIDS prevalence, and small island nations with high diabetes prevalence.

Dr Clark and colleagues allow for the fact that not all individuals with underlying conditions would develop severe symptoms if infected with COVID-19, and they estimate that only 4% of the world’s population would require hospitalisation, suggesting a degree of increased risk that is modest for many people with an underlying health condition.

“Estimates of the number of individuals at increased risk were most sensitive to the prevalence of chronic kidney disease, diabetes, cardiovascular disease, and chronic respiratory disease,” they wrote.

Disease prevalence data were drawn from the Global Burden of Diseases, Injuries and Risk Factors Study (GBD) 2017, UN population estimates for 2020 and the list of underlying health conditions relevant to COVID-19, as defined by current guidelines. The study provides global, regional and national estimates for the number of people with underlying health conditions, but the authors note that the work focused on underlying chronic conditions and did not include other possible risk factors for COVID-19 that are not yet included in all guidelines, such as ethnicity and socioeconomic deprivation. They also assumed that in all age groups under 65, around twice the number of men as women would require hospitalisation.

Risk Groups by Country, Region, and Age

Unsurprisingly, the younger the population of a country or region, the fewer the proportion with one or more underlying health conditions. In Africa, for example, this proportion is around 16% (283 million people out of 1.3 billion), while in Europe it is 31% (231 million out of 747 million). However, Dr Clark points out that even though the proportion of people with at least one underlying health condition is lower in Africa, there is a higher chance of fatality in severe cases compared to many other parts of the world.

Fiji and Mauritius, and other small island nations, have among the highest proportion of people with an underlying condition. In Africa, countries with the highest HIV/AIDS prevalence, such as Eswatini (formerly Swaziland) and Lesotho, qualify as those with a greater proportion of people with an underlying condition than countries with lower prevalence, such as Niger.

From a global perspective, the proportion of people with at least one underlying health condition that places them at greater risk of a poor COVID outcome shows wide variation by age. Fewer than 5% of those under 20 years have an underlying health condition while this figure leaps to more than 66% in those over 70 years. The analysis estimates that 23% of working age people have at least one underlying condition.

COI: Dr Clark and Dr Eggo declare no competing interests.

Published in the June 15 edition of The Lancet Global Health.