Around 1 in 5 people across the world have underlying conditions that put them at risk of developing severe COVID-19 if infected with the coronavirus, according to a new study. That adds up to around 1.7 billion people worldwide.
The novel coronavirus has infected more than 8 million people globally and killed more than 437,900, according to the latest numbers from the Johns Hopkins dashboard. The virus has severely impacted some people, while causing only mild or no symptoms in others, according to a previous Live Science report.
Studies are finding that underlying conditions, age and poverty are all factors that could cause more severe disease. For example, researchers reported yesterday (June 15) in the journal Morbidity and Mortality Weekly Report that rates of hospitalizations are six times higher and rates of death were 12 times higher in COVID-19 patients in the U.S. with underlying conditions, the most common of which were heart disease, diabetes and chronic lung disease.
Now, a group of researchers has focused specifically on how underlying conditions will impact the outcome of the virus on the world's population.
To estimate the risk of severe disease, researchers analyzed several datasets including data from 188 countries reported in a 2017 study that analyzed the global burden of diseases, injuries and risk factors and data from a United Nations population estimate for 2020, according to the report.
Using guidelines from the World Health Organization and agencies in the U.K. and U.S., the authors grouped the underlying conditions that most affected the risk of severe COVID-19 into 11 categories: cardiovascular disease, chronic kidney disease, chronic respiratory disease, chronic liver disease, diabetes, cancers with direct immunosuppression (suppression of the body's immune response due to the cancer), cancers without direct immunosuppression but with possible immunosuppression from treatment, HIV/AIDS, tuberculosis, chronic neurological disorders and sickle cell disorders.
They found that around 22% of the world's population had at least one underlying condition that put them at risk of developing severe COVID-19. Less than 5% of people younger than 20 reported these underlying conditions; that number jumped to more than 66% of those over 70 years of age, the authors found.
What's more, an estimated 1 in 25 people, or 349 million people worldwide, are at risk of severe COVID-19 and would require hospitalization if infected, according to the findings. Again, the risk increased with age: less than 1% of people younger than 20 and around 20% of those 70 and older would require hospitalization, the authors found.
The authors found that the risk of a severe infection was highest in countries with older populations, African countries with high rates of HIV/AIDS and small islands that have high diabetes rates, according to the report.
A "strength" of their model is that it can be modified as new data emerges and "allows for the much needed further stratification of risk to inform a precision public health approach," researchers who were not involved in the study wrote in an accompanying commentary. However, the authors have identified some limitations to their approach, including the fact that they didn't consider age as an independent risk factor in predicting disease severity. In other words, they didn't include healthy older individuals without underlying health conditions in their tallies, according to The New York Times.
What's more, their estimates don't include other prominent risk factors such as ethnicity, poverty and obesity, according to the report. So, "our estimates are uncertain and focus on underlying conditions rather than other risk factors ... but provide a starting point for considering the number of individuals that might need to be shielded or vaccinated as the global pandemic unfolds," the authors wrote in the study.
The findings were published yesterday (June 16) in the journal The Lancet Global Health.
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Originally published on Live Science.