Anecdotal evidence and a strong track record argue for the value of contact tracing in fighting COVID-19's spread.

Now, a global statistical study in the journal Nature Science Reports backs up that assertion with hard numbers.

Of the 138 countries and territories studied, those that employed ample contact tracing showed significantly lower death rates from COVID-19.

The authors said finding, testing and isolating patient contacts early is especially vital with the coronavirus, which is most infectious before symptoms appear.

They added that early detection lets people receive treatment sooner and, together, these factors reduce stress on the health care system.

The study also found countries with higher proportions of people over 70 years old have higher case fatality rates from COVID-19.

The researchers controlled for a variety of economic, population and healthcare variables, including total tests per million, stringency of non-pharmaceutical measures, numbers of physicians and hospital beds, populations, percentages of smokers and diabetics, per capita gross domestic products and the size of fiscal stimulus packages.

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