COVID virus’ incubation time becomes shorter with each new variant

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In a study from Peking University, scientists found that if you get infected with COVID-19, the time from infection to possible onset of symptoms—the incubation period—is significantly shorter now than it was at the beginning of the pandemic.

In the study, the team looked at data from 142 different studies.

They examined data on incubation periods from a myriad of studies conducted throughout the pandemic. A total of more than 8,100 COVID-19 patients were included.

The researchers found that people who got infected with the Alpha variant—the one that emerged in Wuhan in late 2019—had an incubation period averaging 5 days.

When the Beta variant emerged in May 2020, that incubation rate had shortened to about 4.5 days.

The more highly transmissible Delta variant came on the scene in 2021. Its incubation period was even shorter, about 4.4 days, on average.

Incubation time became significantly shorter with the advent of the Omicron variant, however: Just 3.4 days, on average

The findings suggest that SARS-CoV-2 has evolved and mutated continuously throughout the COVID-19 pandemic.

The team says the virus has constantly changed in terms of its ability to transmit between people, its level of severity, and its incubation period.

When COVID-19 first emerged in its Alpha variant, its five-day incubation period was much longer than that seen with other common viral illnesses.

For example, common colds caused by coronavirus have an incubation of about 3.2 days; influenza’s incubation is just under two days, and rhinoviruses (the most common cause of colds) have an incubation of about a day and a half.

The team stressed that the numbers in their study are only averages, and incubation for any one COVID-19 patient could still vary widely.

A shortening of the average incubation period for COVID-19 over time could affect recommendations for self-isolation.

If you care about Covid, please read studies about why some people cannot resist COVID-19 like others, and how COVID-19 pandemic harms blood pressure health.

For more information about Covid, please see recent studies that shark stuff could fight COVID-19 virus, and results showing vitamin D3 could help people fight COVID-19, infections.

The study was conducted by Min Liu et al and published in JAMA Network Open.

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