Part 2: Pfizer-BioNTech Vaccine Trial in Qatar
The best way to determine the efficacy of vaccines against the SARS-CoV-2 variants is to see how protected vaccinated people are in a real world setting. Qatar has a National Federal Covid-19 data collection system and on Dec 21st they launched a mass vaccination program. Data was collected from Feb 1-Mar 31, at a time when the UK variant (B.1.1.7) and the South African variant (B.1.351 each accounted for almost 50% of the coronavirus samples that were genome sequenced in their population. There were 265,410 people who received 2 doses of the vaccine during that time period. They matched PCR positive cases and PCR negative cases by age, sex, and nationality and then calculated the number of cases of Covid-19 in each group more than 2 weeks after their 2nd vaccine dose.
The effectiveness of the vaccine against documented infections, more than 14 days after the 2nd dose, was 89.5% with the B.1.1.7 variant and 75.0% with the B.1.351 variant. In addition the vaccine effectiveness against severe, critical, or fatal disease with these variants was 100% with each variant. However effectiveness after only one dose was much, much lower. Out of the vaccinated group here have been only 1,616 breakthrough cases in patients who received two doses, but 6,689 cases in people who only received one dose. See Below
If you did not get your second dose of Pfizer or Moderna vaccine, please get it now.
Both Pfizer and Moderna are developing an updated mRNA vaccine that targets B.1.351 - which is a mutation of concern. We may not need it, but this mutation from South Africa is one of the most worrisome of the current variants. Next time Part 3: The recent studies of variants in the Israel Vaccine Groups.