FILE — Melva Mlambo, right, and Puseletso Lesofi, both medical scientists prepare to sequence COVID-19 omicron samples at the Ndlovu Research Center in Elandsdoorn, South Africa, Dec. 8, 2021. Health experts still don't know if omicron is causing milder COVID-19 but some more hints are emerging with doctors in South Africa saying their patients aren't getting as sick with omicron, compared to the delta variant. (AP Photo/Jerome Delay, File)