However, it did remain 90% effective against hospitalisation.
The effectiveness of the Pfizer-BioNTech goes down to 47% after six months, according to a new study.
Two doses of the Pfizer-BioNTech vaccine are 90% effective against hospitalisation regardless of variant for at least six months but only 47% effective against infection, the peer-reviewed analysis found.
The study published in
The Lancet Journal, also found that reductions in the vaccine's effectiveness against Covid-19 was due to waning over time as opposed to the Delta variant or other new strains of the virus.
Researchers looked at the health records of 3,426,957 people who had received the vaccine, revealing that 5.4% (184,041) had been infected with the virus and 6.6% of those people (12,130) were hospitalised.
All of the participants were aged over 12, with the median age being 45-years-old.
Among those infected with the virus, a higher proportion of those who were admitted to hospital for Covid-19 were also older, men and had underlying health conditions.
28% of positive tests were from people infected with the Delta strain of the virus, which may be due to the rapid increase in cases of the Delta variant over recent months.
The authors said that there are some limitations in the study such as the vaccination status of the group not being randomised as well as a lack of data on adherence to guidelines, social interactions and occupation for the participants.
