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Incubation period dropped with each new variant; what this means as COVID-19 still spreads

INDIANAPOLIS (WISH) – At the start of the pandemic the coronavirus brewed inside an infected person’s body for up to one week with patients showing no signs or symptoms for as many as 12 days. This was a major reason why COVID-19 was such a threat in the beginning. Patients were spreading the deadly disease without even knowing it.

New research shows the incubation period has dropped with each new mutation first going from five days for the Alpha variant to 4.5 days for the Beta variant. It then fell to an average of 4.4 days when Delta emerged. Now the number sits at an incubation period of 3.4 days for Omicron. 

Could this explain why COVID-19 is spreading more quickly with each new mutation?

“I think that’s a possible explanation of the increased contagiousness,” Christopher Doehring, vice president of medical affairs at Franciscan Health, told News 8. “Just how efficiently these viruses are spreading and so the newer sub variants of omicron do seem to be spreading a lot more efficiently and rapidly. The shorter incubation time is certainly part of that.”

Might this also explain why current COVID-19 strains cause less severe illness?

“How much the virus changes and how it evolves with subsequent sub variants and each successive generation could certainly be impacted by this process,” said Doehring. “Does that lead to a risk of a higher virulence or a lower virulence? It seems to be at least at this point. The BA.4 and BA.5 are less severe. But the jury is still somewhat out on that.” 

This news comes as the World Health Organization announced the number of coronavirus deaths reported worldwide has fallen by 15% in the last week while new infections dropped by 9%.