Two days ago, in MMWR: COVID-19 Case Surveillance — U.S., Jan 22–May 30, 2020, I quoted the National Health Council's estimate that 40% of Americans (157 million) have chronic health problems, and 81 million have multiple conditions.
While not all of these comorbidities are significantly aggravating factors for COVID-19 infection, many of them are. With roughly only 5% of the nation's population thus far infected, we've only seen a sample of the harm the virus could do should it continue to spread.The situation world-wide isn't much better, although nations will much younger demographics might fare better than those with older populations. Those gains, however, could be offset by other factors, such as malnutrition, the incidence of other diseases (e.g., HIV/AIDS, Diabetes, etc.), and a lack of public and private healthcare.
In an attempt to quantify the number of people around the world who are at enhanced risk of severe disease from COVID-19, researchers from the London School of Hygiene and Tropical Medicine (LSHTM) have published a modeling study that finds about 1 in 5 people globally have an increased risk of severe disease from COVID-19, and 4% (349 million) are at high risk.
First a link and some excerpts from the study, then a link to a press release from LSHTM.
Global, regional, and national estimates of the population at increased risk of severe COVID-19 due to underlying health conditions in 2020: a modelling study
Andrew Clark, PhD Prof Mark Jit, PhD Charlotte Warren-Gash, PhD Prof Bruce Guthrie, PhD Harry H X Wang, PhD Prof Stewart W Mercer, PhD et al.
Open Access Published:June 15, 2020
DOI:https://doi.org/10.1016/S2214-109X(20)30264-3PDF FILE
Summary
Background
The risk of severe COVID-19 if an individual becomes infected is known to be higher in older individuals and those with underlying health conditions. Understanding the number of individuals at increased risk of severe COVID-19 and how this varies between countries should inform the design of possible strategies to shield or vaccinate those at highest risk.
Methods
We estimated the number of individuals at increased risk of severe disease (defined as those with at least one condition listed as “at increased risk of severe COVID-19” in current guidelines) by age (5-year age groups), sex, and country for 188 countries using prevalence data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017 and UN population estimates for 2020. The list of underlying conditions relevant to COVID-19 was determined by mapping the conditions listed in GBD 2017 to those listed in guidelines published by WHO and public health agencies in the UK and the USA.
We analysed data from two large multimorbidity studies to determine appropriate adjustment factors for clustering and multimorbidity. To help interpretation of the degree of risk among those at increased risk, we also estimated the number of individuals at high risk (defined as those that would require hospital admission if infected) using age-specific infection–hospitalisation ratios for COVID-19 estimated for mainland China and making adjustments to reflect country-specific differences in the prevalence of underlying conditions and frailty. We assumed males were twice at likely as females to be at high risk.
We also calculated the number of individuals without an underlying condition that could be considered at increased risk because of their age, using minimum ages from 50 to 70 years. We generated uncertainty intervals (UIs) for our estimates by running low and high scenarios using the lower and upper 95% confidence limits for country population size, disease prevalences, multimorbidity fractions, and infection–hospitalisation ratios, and plausible low and high estimates for the degree of clustering, informed by multimorbidity studies.
Findings
We estimated that 1·7 billion (UI 1·0–2·4) people, comprising 22% (UI 15–28) of the global population, have at least one underlying condition that puts them at increased risk of severe COVID-19 if infected (ranging from < 5% of those younger than 20 years to > 66% of those aged 70 years or older).
We estimated that 349 million (186–787) people (4% [3–9] of the global population) are at high risk of severe COVID-19 and would require hospital admission if infected (ranging from < 1% of those younger than 20 years to approximately 20% of those aged 70 years or older). We estimated 6% (3–12) of males to be at high risk compared with 3% (2–7) of females.
The share of the population at increased risk was highest in countries with older populations, African countries with high HIV/AIDS prevalence, and small island nations with high diabetes prevalence. 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.
Interpretation
About one in five individuals worldwide could be at increased risk of severe COVID-19, should they become infected, due to underlying health conditions, but this risk varies considerably by age. 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.
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Estimates suggest one in five people worldwide have an underlying health condition that could increase their risk of severe COVID-19 if infected
16 June 2020
An estimated 1.7 billion people, 22% of the world population, have at least one underlying health condition that could increase their risk of severe COVID-19 if infected, according to a modelling study that uses data from 188 countries, published in The Lancet Global Health.
Although the estimates provide an idea of the number of people governments should prioritise for protective measures, not all individuals with these conditions would go on to develop severe symptoms if infected. The authors estimate that 4% of the world’s population (349 million of 7.8 billion people) would require hospitalisation if infected, suggesting that the increased risk of severe COVID-19 could be quite modest for many with underlying conditions.
Dr Andrew Clark, Associate Professor at the London School of Hygiene & Tropical Medicine (LSHTM), said: “As countries move out of lockdown, 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 prioritising them for vaccination in the future.”
Guidelines published by the WHO and by public health agencies in the UK and USA identify risk factors for severe COVID-19, including cardiovascular disease, chronic kidney disease, diabetes and chronic respiratory disease.
The new study provides global, regional and national estimates for the number of people with underlying health conditions. The researchers caution that they focused on underlying chronic conditions and didn’t include other possible risk factors for COVID-19 that are not yet included in all guidelines, such as ethnicity and socioeconomic deprivation. Their estimates are therefore unlikely to be exhaustive, but serve as a starting point for policy-makers.
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While it remains true that most people who contract COVID-19 will experience a mild or moderate illness and then recover, for well over a billion people around the globe, the risks are much greater.
