Two studies have confirmed that the protection against coronavirus infection provided by the COVID-19 vaccine developed by Pfizer Inc (NYSE:PFE) and BioNTech falls after a few months, although the vaccine’s protection against hospitalisation and death remains strong.
The studies, from Israel and from Qatar, were published in the New England Journal of Medicine.
The Qatar study of peope with actual infections showed that the protection against infection provided by the Pfizer-BioNTech vaccine, known as BNT162b2, peaked in the first month and then waned gradually, with the decline accelerating after the fourth month to reach approximately 20% after between five and seven months following the second dose.
However, protection against hospitalisation and death stayed above 90% for six months after the second dose.
“These findings suggest that a large proportion of the vaccinated population could lose its protection against infection in the coming months, perhaps increasing the potential for new epidemic waves,” the researchers wrote.
In Israel, a study of more than 4,800 health care workers showed that protection after two doses of vaccine decreased substantially after six months, "especially among men, among persons 65 years of age or older, and among persons with immunosuppression".
Pfizer has said that immunity from the first two doses of its vaccine begins to drop after a few months.
A recent peer-review analysis, published in the Lancet medical journal, found that two doses of the vaccine were 90% effective against COVID-19 hospitalisation for at least six months, but only 47% effective against infection after that period.
READ: COVID-19: Pfizer vaccine protection drops to 47% after six months