Omicron: Less Virulent But Still Dangerous

The rapid rise of Omicron variant infections around the world has led the virological community to take a closer look at the extremely infectious strain. Early data clearly indicates that Omicron is far more transmissible than strains that came before. One study estimates that Omicron is 2.7 to 3.7 times more transmissible than the Delta variant among vaccinated individuals. However, it seems Omicron may not be as virulent, or intense in terms of symptoms, as earlier strains like Alpha and Delta, particularly in vaccinated individuals. The Moderna, Pfizer, Johnson & Johnson, and AstraZeneca vaccines appear to protect against severe disease consequences. However, it is likely that in the unvaccinated, Omicron will still cause severe illness, and as such should not be taken lightly. Director-General of the World Health Organization Tedros Adhanom Ghebreyesus notes that “While Omicron does appear to be less severe compared to Delta, especially in those vaccinated, it does not mean it should be categorized as mild.”

Omicron’s infectivity stems from a couple of factors. Firstly, it appears to overcome full vaccination and booster shot protection against infection, meaning the virus has more hosts at its disposal. Secondly, Omicron replicates extremely rapidly in the nasopharynx, more so than the strains that came before. Thirdly, Omicron transmits from asymptomatic individuals at a much higher rate than previous strains. For the Delta variant, asymptomatic transmission rates were between 1% and 2.6%. The rate for Omicron is over 30%, according to a study by Garrett et al.

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© William A. Haseltine, PhD. All Rights Reserved.