Omicron to become dominant variant in Denmark this week

A new study from South Africa indicates that Pfizer/BioNTech’s vaccine is only about 33% effective against the Omicron variant of coronavirus, but people infected with the Omicron variant are less likely to end up in the hospital than those infected with the original strain of the virus.

The data comes from Discovery Health, a large health insurance company that covers 3.7 million people in South Africa. The team there, along with researchers at the South African Medical Research Council, looked at claims data coming from the time when Omicron became predominant across South Africa, and compared it to data from earlier periods.

They examined 211,000 positive coronavirus test results, 41% of them taken from adult members who had been given two doses of Pfizer’s vaccine. The company estimated 78,000 of these cases involved Omicron between November 15 and the first week of December.

They estimate the risk of ending up in the hospital from Covid-19 was 29% lower for Omicron infections in adults, compared to the original virus, but said children were 20% more likely to be hospitalized. The comparison was to one of the first strains of the virus, not to the Alpha or Beta variants that were prevalent in South Africa this year.

Two doses of the Pfizer vaccine was 33% protective against infection overall, but 70% effective in preventing severe complications including hospitalization, they said. 

“The Omicron-driven fourth has a significantly steeper trajectory of new infections relative to prior waves. National data show an exponential increase in both new infections and test positivity rates during the first three weeks of this wave, indicating a highly transmissible variant with rapid community spread of infection,” Dr. Ryan Noach, CEO of Discovery Health, said in a statement.

“Overall, the risk of re-infection following prior infection has increased over time, with Omicron resulting in significantly higher rates of reinfection compared to prior variants,” Shirley Collie, chief health analytics actuary at Discovery Health, said in a statement. Collie said people in South Africa’s Delta wave had a 40% relative higher risk of reinfection with Omicron and those infected when Beta predominated had a 60% higher relative risk of reinfection with Omicron.

“Notwithstanding the fact that children continue to show a very low incidence of severe complications following Covid-19, Discovery Health’s data indicate that children under age 18 have 20% higher risk of admission for complications of Covid-19, when infected with Omicron,” Collie added.

“This is early data and requires careful follow up. However, this trend aligns with the South Africa’s National Institute for Communicable Diseases (NICD) warning in recent days that during South Africa’s third wave of infection (June to September 2021) they had seen an increase in pediatric admissions and now, in the fourth wave, they are seeing a similar increase in admissions for children under five. Anecdotal reports from hospitals in South Africa indicate that most Covid-19 diagnoses in children admitted to hospital are co-incidental — many children that are admitted for non-COVID related conditions, and are not experiencing Covid-19 complications, test positive for Covid-19 on routine screening tests.”