A two-dose Pfizer / BioNTech vaccination provides only 33% protection against infection with the omicron variant of coronavirus, but 70% protection against hospitalization, according to a large-scale analysis in South Africa published on Tuesday.
The first large-scale analysis of the vaccine’s effectiveness in the region where the new variant was discovered seems to support early indications that omicron is more easily transmissible and that the Pfizer shot is not as effective at protecting against infection as it was. against the delta variant. .
The analysis was based on more than 211,000 positive COVID-19 test results, 41% from adults who had received two doses of the Pfizer vaccine. About 78,000 of these positive COVID-19 test results between November 15 and December 7 were attributed to omicron infections. The study was conducted by Discovery Health, South Africa’s largest private health insurance company, and the South African Medical Research Council.
The study has been conducted in the weeks since omicron was first announced in November by scientists in South Africa and Botswana. The researchers stressed that its results are preliminary and not peer reviewed.
The data is collected from the first three weeks of South Africa’s omicron-driven wave and may change as time goes on. South Africa is the first country to experience an increase in COVID-19 driven by the omicron variant.
South Africa has experienced rapid societal proliferation – concentrated in its most populous province, Gauteng – dominated by the omicron variant.
The rolling seven-day average of daily new cases in South Africa has risen over the last two weeks from 8.07 new cases per year. 100,000 people on November 29 to 34.37 new cases per. 100,000 people on Dec. 13, according to Johns Hopkins University. The death rate has not increased in the same period.
“Excellent genetic monitoring by the Network for Genomic Surveillance in South Africa identified that omicron infection accounts for over 90% of new infections in South Africa, and has displaced the former dominant delta variant,” said Discovery Health CEO Dr. Ryan Noach.
“The omicron-driven fourth wave has a significantly steeper trajectory for new infections compared to previous 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 the rapid spread of infections in the community, ”said Noach.
The results show that vaccinated individuals who received two doses of the Pfizer vaccine have 33% protection against infection from omicron, compared to those who were unvaccinated in the first weeks of South Africa’s current omicron-driven wave. This represents a significant decrease over the 80% protection against infection given in the earlier period, probably on the basis of lower antibody sensitivity, following the extensive peak protein mutations in the omicron variant.
Encouragingly, however, the results show that the same vaccinated individuals who received two doses of the Pfizer vaccine have 70% protection against hospitalization during the same period. This hospitalization protection has been reduced from the 93% highs in South Africa’s delta-driven variant.
The study shows that protection against hospitalization is maintained across all ages, in people aged 18 to 79, with slightly lower levels of protection for the elderly, with 67% in people aged 60 to 69 and 60% in people aged 70 years. to 79. Protection against hospitalization is also consistent across a range of chronic diseases, including diabetes, hypertension, hypercholesterolemia, and other cardiovascular diseases.
The study also found:
Omicron poses a higher risk of re-infection. For individuals who have previously had COVID-19, the risk of reinfection with omicron is significantly higher than for previous variants.
2. The risk of admission from omicron is lower. Hospital admissions among adults diagnosed with COVID-19 attributed to omicron are 29% lower compared to the COVID-19 wave that South Africa experienced in mid-2020, after adjusting for vaccination status.
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