Data from Discovery Health, South Africa’s largest private health insurer. Based on 211,00 COVID-19 test results from November 15- December 7th, 2021. Includes 78,000 Omicron samples out of 211,000 (133,000 Delta Variant cases).
- Vaccine effectiveness:
- o The two-dose Pfizer-BioNTech vaccination provides 70% protection against severe complications of COVID-19 requiring hospitalization, and 33% protection against COVID-19 infection, during the current Omicron wave.
- Reinfection risk: For individuals who have had COVID-19 previously, the risk of reinfection with Omicron is significantly higher, relative to prior variants.
- Severity: The risk of hospital admission among adults diagnosed with COVID-19 is 29% lower for the Omicron variant infection compared to infections involving the D614G mutation in South Africa’s first wave in mid-2020, after adjusting for vaccination status
- Children: Despite very low absolute incidence, preliminary data suggests that children have a 20% higher risk of hospital admission in Omicron-led fourth wave in South Africa, relative to the D614G-led first wave
Insights and Takeaways: With an only 29% reduction in hospitalizations for a disease that is 4 X more transmissible and with immune escape does not portend to a walk in the park. The projections are that this next wave will be considerably costly and marked by overrun hospitals and clinics. Furthermore, the 29% reduction in severe disease could be more a reflection of community immunity from a population that has a high level of immunity from previous infection. (SA is on its fourth wave of CV-19) This data does suggest that the early reports of decreased virulence could be more wishful thinking than reality. The true test will be how Omicron affects the unvaccinated, never infected cohort.
It also does appear that vaccines do provide significant protection albeit much less than with previous waves. A 70% reduction in hospitalizations in patients that received 2 doses of Pfizer without a booster is very encouraging. After a booster the protection rises to about 90%, meaning that the mutations have not rendered the vaccines ineffective.
Some good news is that after 3 weeks of activity in SA, Omicron seems to have peeked, suggesting that it will rise fast and drop fast, thus limiting the length of time for social disruption.
The hallmark of Omicron will be its rapid spread throughout the community due to immune escape from multiple spike protein mutations. The mutations however are not fatal as vaccines and prior infection appear to be providing relatively strong protection from severe disease albeit to a lesser degree than previous variants.
Limitations of the study. This is a study of insured patients. 41% of vaccinated persons in this cohort do not represent the 26% vaccination rate in all of SA. Insured individuals are likely to have more means and access to better nutrition and medical care which may artificially skew the outcome in a positive manner. This is a press release and not a peer reviewed data set that may be subject to bias and error. This is only one non controlled study. Things may change in the near future as the data changes. We will know more in two weeks with regard to the risk of hospitalization and death as the disease in SA appears to have hit its peak. We are also two weeks from a significant surge thus I do expect to see an increase in hospitalizations and deaths so we will learn more in the coming days.
We still have multiple questions. However, with these results it would be extremely wise for the unvaccinated to get vaccinated and the elderly and the at risk to boost. There is good rationale for everyone over the age of 40 to receive a booster (and 18-40 with comorbid conditions). Moreover, if Omicron proves to be more contagious than we thought, vaccinating and boosting the entire eligible population is the right strategy simply because, the world is about to be overrun with Coronavirus cases that will surely overwhelm our healthcare system. Since we might see more disease in children, although with still very low risk of serious illness, it would not be wrong to vaccinate our children down to age 5 and also provide additional mitigation strategies for our children under the age of 5.