Earlier this month, doctors at the Steve Biko/Tshwane District Hospital Complex, a major medical center in Pretoria, released a report describing the clinical condition of covid patients admitted during the current surge. On December 2nd, there were forty-two patients, of whom just fourteen required supportive oxygen (and not all necessarily because of the virus), and only one was admitted to the I.C.U. In recent weeks, the average length of hospitalization was three days, compared with about nine in the past; the mortality rate has been roughly a third of what it was. “I’ve never seen this picture before,” Fareed Abdullah, the report’s lead author, said. “At this stage of the beginning of the fourth wave, the main presentation is incidental covid”—patients who came in for other reasons and happened to be carrying the virus.

Although these findings are encouraging, it’s important not to place too much stock in them. Most recent patients at the Tshwane District Hospital have been under the age of fifty—a group with a relatively low risk for severe illness, and, in South Africa, a very low immunization rate. It’s also possible that some of Omicron’s perceived “mildness” is a reflection of its immune-evasiveness: early evidence suggests that it may be nearly three times as likely as other variants to cause repeat infections. If Omicron leads to milder symptoms in people who haven’t previously been infected or vaccinated, that would be reason for comfort; if, instead, it produces illness requiring hospitalization in those who’ve survived a prior infection, that’s cause for concern.