Prevalence of asymptomatic disease: An estimated 40–45% of people who test positive for SARS-CoV-2 do not have symptoms at the time of testing, according to a narrative review of 16 cohorts in the Annals of Internal Medicine. In four cohorts with longitudinal data, few of the asymptomatic patients (0–10%) went on to develop symptoms. But in one skilled nursing facility, 89% of initially asymptomatic patients became sick. The researchers say, “It is imperative that testing programs include those without symptoms.” They add, “The early data that we have assembled on the prevalence of asymptomatic SARS-CoV-2 infection suggest that this is a significant factor in the rapid progression of the COVID-19 pandemic.”
Smoking cigarettes — even one or less per day — is associated with increased mortality risk, a JAMA Network Open study shows. Researchers combined data from several federal smoking surveys performed between 1992 and 2011. In those surveys, some 500,000 adults reported their smoking histories. National mortality data showed that, compared with never-smokers, daily smokers (averaging 600 cigarettes per month) bore a 2.3-fold higher all-cause mortality risk, with non-daily smokers (averaging 40 per month) sustaining a 1.8-fold higher risk. Heightened mortality risks became apparent even at levels of 6 to 10 cigarettes per month. The researchers conclude: “Thus, all smokers should quit, regardless of how infrequently they smoke.”
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