According to the results of a large-scale study conducted in South Africa, two doses of the Pfizer/BioNTech vaccine are only 33 percent effective against infection caused by the Omicron variant; however, it prevents the risk of hospitalization by 70 percent.
Large-scale analysis of vaccine efficacy in South Africa, where the Omicron variant was first detected, confirms initial findings that Omicron is more contagious and not as effective as Pfizer’s vaccine against Omicron in Delta.
The analysis included 211,000 positive Covid-19 test results, seen in 41 percent of adults who received two doses of Pfizer vaccine. Among the positive Covid-19 tests detected between November 15 and December 7, 78 thousand Omicron variants were detected. The study was led by Discovery Health, South Africa’s largest private health insurance firm, and the South African Medical Research Council.
Scientists from South Africa and Botswana conducted the study in the weeks following the announcement that the Omicron variant had emerged. Experts noted that the results are preliminary and not evaluated by independent scientists.
It is stated that the data collected in the first three weeks of the infection wave caused by the Omicron variant in South Africa may change over time.
In Guateng, the most populated region of South Africa, the number of infections due to the Omicron variant had increased rapidly.
According to data from Johns Hopkins University, the seven-day average number of cases in South Africa has risen rapidly in the last two weeks. The number of new cases, which was 8.07 per 100 thousand on 29 November, increased to 34.37 per 100 thousand on 13 December. However, death rates did not increase during the same period.
“Omicron replaces Delta in South Africa”
Discovery Health’s CEO, Dr. “The remarkable process by the Genomic Observation Network in South Africa has revealed that over 90 percent of new infections in South Africa are caused by Omicron. Omicron has replaced the formerly dominant Delta variant,” said Ryan Noach.
Dr. “The fourth wave from Omicron shows a much faster rise in new infection cases compared to previous epidemic waves. National data reveals that during the first three weeks of this wave, there was a coefficient increase in both new infection cases and positive Covid test rates. “This shows that the new variant is very contagious and is spreading rapidly in the community.”
The results of the study reveal that in the first week of the current epidemic wave in South Africa, people who received two doses of the Pfizer vaccine had 33 percent protection against infections from Omicron compared to those who were not vaccinated. This data shows that the Pfizer vaccine is rapidly declining from the previous 80 percent protection rate. This is thought to be due to the reduced effectiveness of antibodies due to extensive spike protein mutations in the Omicron variant.
The results also indicate that the same people who received two doses of the Pfizer vaccine had a 70 percent reduced risk of hospitalization for the Omicron variant during the period covered by the study. In South Africa, when the Delta variant was dominant, the risk of hospitalization was reduced by 93 percent with two doses of Pfizer.
On the other hand, the research reveals that the protection against hospitalization is valid in all age groups from 18 to 79, while the level of protection decreases somewhat in the elderly. According to this, people aged 60-69 are protected from hospitalization by 67 percent with two doses of Pfizer vaccine, and those aged 70-79 are protected by 60 percent. Protection against the risk of hospitalization is also consistent in some chronic conditions such as diabetes, heart disease, high blood pressure and high cholesterol.
“High risk of reinfection”
The research also reveals that the Omicron variant increases the risk of being reinfected. People who have previously had Covid-19 have a higher risk of being reinfected with the Omicron variant compared to previous variants.
On the other hand, it is observed that the risk of hospitalization due to Omicron is lower. The hospitalization rate among adults infected with the Omicron variant is 29 percent lower than in South Africa’s wave of infections in mid-2020. This rate emerged by rearranging the data according to the vaccination status of the individuals.