The proportion of those testing positive for SARS-CoV-2 who are symptom-free is 40 percent. That’s the conclusion of a meta-analysis of international studies involving nearly 30 million people.
Origin of corona transmission
Qiuyue Ma and co-authors from the Department of Epidemiology and Biostatistics at Peking University recently published their findings in JAMA Open, an online publication of the American Medical Association. “Asymptomatic infections are potential sources of covid-19 transmission, and the aim was to determine the percentage of asymptomatic infections among those tested and those with confirmed covid-19 disease,” the researchers wrote.
Experts analyzed numerous studies
The experts reanalyzed 95 studies conducted and published worldwide, involving 29.8 million people. Around the globe, after all, studies on the spread of SARS-CoV-2 have been conducted in virtually every country with even a somewhat functioning healthcare system since the start of the Covid-19 pandemic.
“Asymptomatic individuals with a positive SARS-CoV-2 test (asymptomatic infection) were defined as those who had no signs of disease at the time of testing or diagnosis,” the scientists wrote. Only positive PCR testing from swabs, etc., was scored for a confirmed diagnosis.
Presence of asymptomatic infections
Overall, asymptomatic infections were present at a frequency of 0.25 percent in all those tested. The frequency was 4.52 percent among nursing home residents and 2.02 percent among air or sea travelers. Pregnant women without signs of illness had a positive test at 2.34 percent. This demonstrated the prevalence of infections at the time of testing in each group of people.
More importantly, however, the percentage of symptom-free individuals despite already clearly confirmed Covid-19 infection was strikingly high: 40.5 percent. Among pregnant women affected by Covid-19, 54.11 percent showed no signs of illness, as did 52.91 percent of SARS-CoV-2-infected air or sea travelers and 47.53 percent of nursing home residents with positive findings. “The high proportion of asymptomatic infections underscores the extent of transmission risk from symptomless people in the community,” the Chinese scientists noted.
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