The second dose of Pfizer Inc.’s COVID-19 vaccine could be delayed in order to cover all priority groups as the first one if highly protective, two Canada based researchers have said in a letter published in New England Journal of Medicine. While Pfizer had previously said that its vaccine had an overall efficacy of 94.8 per cent, the researcher duo highlighted that the efficacy of its first dose alone was 92.6 per cent. The conclusion by Danuta Skowronski and Gaston De Serres was based on an analysis of the documents submitted by the drugmaker to the US Food and Drug Administration (FDA).
The mRNA based vaccine BNT162b2 developed jointly by Pfizer and BioNTech was the first vaccine to gain approval by health regulators. As of now, it is being used in the majority of nations including the UK, the US, Israel, EU, Mexico amongst others. However, due to a dearth of jabs, many states were now mulling to change their dosing patterns or volumes.
However, Skowronski and De Serres cautioned that there may be uncertainty about the duration of protection with a single dose, but said the administration of the second dose a month after the first provided "little added benefit in the short term". Meanwhile, Pfizer Inc. has left it to the governments to decide on the dosing patterns. While EU and US remain firm on the interval tested on trials, the UK is mulling to change the dozing pattern to 12 weeks.
Meanwhile, a new study conducted by Pfizer shows that its COVID-19 vaccine is less effective against the South African variant B.1.351. The study, published in the New England Journal of Medicine, was conducted to determine the capability of blood serum from individuals vaccinated with the Pfizer/BioNTech vaccine. The study analysed three genetically engineered recombinant viruses with mutations found in the South African variant. The results show that Pfizer's vaccine protection significantly reduces against the South African variant.