Two-thirds of COVID-19 cases may be undiagnosed

Up to 80% of COVID-19 cases are mild or asymptomatic and therefore unlikely to be diagnosed. Determining what percentage of the population is asymptomatic will allow us to know how close we are to achieving herd immunity for COVID-19 and when it is safe to loosen isolation and quarantine restrictions, says GlobalData, a leading data and analytics company.

As the pandemic has crossed over two million cases worldwide with over 187 countries affected, this need has become crucial.

Bishal Bhundari, Senior Epidemiologist at GlobalData, comments: “GlobalData epidemiologists forecast that of the total number of diagnosed and undiagnosed cases in the US last week, two-thirds were undiagnosed. Approximately 250,000 cases in China were still undiagnosed.”


Bhandari concludes: “If we extrapolate the total infection rate for undiagnosed and diagnosed cases from these countries to the rest of the world, no country is close to herd immunity – where at least 60% of the population needs to be exposed to the virus to build up a combined immunity.

“This data implies that herd immunity has yet to be established, and that countries can expect to see second and third waves of infection once lockdown restrictions are relaxed. Lockdown measures may also need to be slowly released to allow better governmental monitoring of secondary outbreaks.”

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