Effectiveness of Pfizer-BioNTech Covid-19 vaccine wanes after six months: Report

PfizerInc-BioNTech vaccine’s effectiveness in preventing infection from Covid-19, declined from 88% to 47%, six months after the second dose, according to data published on Monday, Reuters reported. This comes on the back of health agencies in the US who were considering the necessity for booster shots. For at least six months the vaccine’s effectiveness in preventing hospitalization and death, including the deadly delta variant, remained high at 90%. The data suggested that the fall was due to waning efficacy, rather than more contagious variants, as per researchers.

According to Pfizer vaccines, the variant-specific analysis showed that the vaccine is effective against all variants, including the delta variant.

Delta is not an escape variant

In the first month, the vaccine’s effectiveness against delta variant was 93%, and four months later it declined to 53%. For other Covid variants, the efficacy declined from 97% to 67%.

At the same time researchers argue that this does not suggest that the delta is not an escape variant, which is evading vaccine protection. And, if that was the case then there would not have been such a high protection after vaccination, as vaccination would not be working, they added. It would start low and stay low.

Meanwhile, the authors of the study cautioned that testing for variants is more likely to fail in individuals who are vaccinated, which could lead to an overestimation of variant-effectiveness in the study.

For older adults and some Americans who are at a higher risk of getting infected the U.S. Food and Drug Administration has authorized the use of a booster dose of Pfizer-BioNTech vaccine.