Study: Corona virus became faster and faster

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SARS-CoV-2 got “faster and faster” at triggering Covid-19 as its variants evolved. Chinese biostatisticians have now analyzed 142 studies on the incubation period issue.

The result they published in their paper online in the Journal of the American Medical Association (JAMA): Between the alpha variants and omicron, incubation time dropped from an average of five days to 3.42 days.

“Incubating” a covid infection.
Four to five, later five to six days – these were the expert statements at the beginning of the Covid 19 pandemic regarding the “incubation” of a SARS-CoV-2 infection until the first appearance of symptoms. This is important because infectiousness is already present in those affected during this time and necessary quarantine times can also be calculated after this. That is why numerous scientific studies have been conducted worldwide since 2020.

Yu Wu of the Department of Epidemiology and Biostatistics at Peking University and his co-authors systematically searched through 142 studies up to March 21022 on the incubation period of SARS-CoV-2. They classified them according to the predominant viral variants in each case. The data came from 8,112 Covid-19 patients. The results are now published in JAMA Network Open.

The trend is clear; the researchers say: “The results suggest that SARS-CoV-2 has continuously evolved and mutated across the Covid-19 pandemic. Variants emerged with varying ease of transmission and severity of disease initiation.”

For example, the mean incubation time for SARS-CoV-2 of the alpha variant (2020) was still five days. The beta variants triggered the first symptoms after a mean of four and a half days. A mean incubation time of 4.41 days was recorded for SARS-CoV-2/delta in the fall and winter of 2021, respectively. Omicron works the “fastest.” It takes a mean of only 3.42 days from infection to symptoms.

Across all variants of the covid-19 pathogens, the incubation time was 6.57 days. The range was enormously wide, from 1.80 to 18.87 days. Older adults (over 60) became ill on average as early as 7.42 days after infection, whereas, in people under 18, the incubation period averaged 8.82 days.