If Delta foretells what Omicron will bring and the latest Delta booster data from Israel remains applicable, here is what we might expect from Omicron:
1. More infections among the unvaccinated; unvaccinated individuals are likely to experience approximately the same rates of severe illness that we’ve seen throughout the pandemic.
2. More infections among recovered Covid-19 patients; more infections among the vaccinated than were caused by earlier variants, and likely even more infections among boosted individuals than we’ve seen before.
3. Somewhat higher rates of severe disease among unboosted people starting around age 50 among those who get infected compared to previous variants (both the boosted and unboosted rates of severe disease get markedly worse by decade, especially those over ages 70 and 80); no major change in the rates severe disease for unboosted people under 40 who get infected compared to previous variants. For people ages 40-49, the data are murkier. In the latest study, researchers in Israel lumped severe disease outcomes for those ages 40-49 and 50-59 together; but when I analyzed just the data for those ages 40-49, I found no compelling signal suggesting that boosting prevented severe illness among the infected in that younger subset.