May cause milder disease…but may not

COVID-19 cases in South Africa that are likely caused by the omicron are milder than those caused by the delta variant. “They are able to manage the disease at home,” Unben Pillay, a South African physician, told the Associated Press in story published Saturday (Dec. 11).

But Natalie Dean, Ph.D., an assistant professor at Emory’s School of Public Health, argued persuasively on a Twitter thread that omicron may seem to be causing fewer severe cases because it is resulting a greater number of milder cases through reinfection. Put another way, the ratio of severe-to-mild cases is smaller than other variants because of the people reinfected with omicron experience mild cases of COVID-19.

Booster makes a big difference

British researchers reported in preprint last week that the effectiveness of the Pfizer vaccine at preventing symptomatic disease caused by the omicron variant wanes after two shots, dipping below 40%, but jumps back up to over 70% with a third dose. Their research also shows waning effectiveness against the delta variant, but the fall off isn’t a steep. A third jab boosts effectiveness back up to about 90%.

Osterholm: 3 doses should be the norm

Michael Osterholm, Ph.D., is director of the Center for Infectious Disease Research and Policy at the University of Minnesota and was a member of the Biden COVID task force during the transition. In interview with CNN last week, he said three doses should be the norm.

“The whole world should have access to three doses of a mRNA Covid vaccine,” Osterholm told Anderson Cooper, “and there would be nothing more tragic to me than having someone protected by a two-dose regimen for six to eight months, and then to get seriously ill and die because they didn’t get a booster. I think that one day this won’t even be a question. It will be a minimum three-dose vaccine.”

South African Research: Pfizer vax may not be protective. But against severe disease, definitely may be.

In a study of 14 plasma sample from 12 individuals, South African researchers tested whether the omicron variant would be recognized and defeated by antibodies. They reported results in a preprint posted on Friday that the omicron “escapes”the antibodies generated by the Pfizer vaccine and, according to their calculations, the vaccine would have only 22% efficacy against symptomatic infection.

But that doesn’t address the issue of protection against severe disease. Sandile Cele and his colleagues noted that the omicron’s “escape” from the antibodies is incomplete. The vaccine may be effective against severe disease, they noted, partly because T cells would come into play and, they said, T cell immunity is unlikely to be strongly decreased with omicron infection.

Interestingly, Cele and his colleagues found that the combination of a history of coronavirus infection and Pfizer vaccination produced antibody levels that would fend off infection.

Topol’s good news–bad news chart

Eric Topol, M.D., is founder and director of the Scripps Research Translational Institute in La Jolla, California, and the author of several books. But more recently he has become an influential voice on COVID-19 through this frequent posts on Twitter. Here is a chart of good news and bad news about the omicron that Topol tweeted on Friday:

How to pronounce omicron?

Egbert Bakker, a professor of ancient Greek at Yale told the Wall Street Journal that the letter is pronounced “AWE-mee-kron” in both modern and ancient Greek. Bakker said “oh-Mike-ron” is an acceptable if Americanized pronunciation.

Merriam-Webster gives “AH-muh-kraan” as the first pronunciation, “OH-muh-kraan” as the second and “OH-my-kran” as the British.