LONDON – The effectiveness of the Pfizer vaccine against Covid-19 declines faster than that of the AstraZeneca jab, according to a new study published today.
“Two doses of Pfizer-BioNTech have greater initial effectiveness against new Covid-19 infections, but this declines faster compared with two doses of Oxford-AstraZeneca,” said researchers at Oxford University.
The study, which has not been peer-reviewed, is based on the results of a survey by Britain’s National Statistics Office that carried out PCR tests from last December to this month on randomly selected households.
It found that “the dynamics of immunity following second doses differ significantly” between Pfizer and AstraZeneca, according to the varsity’s Nuffield Department of Medicine.
Pfizer has “greater initial effectiveness”, but sees “faster declines in protection against high viral burden and symptomatic infection” when looking at a period of several months after full vaccination, although the rates remain low for both jabs.
“The results suggest that after four to five months, (the) effectiveness of these two vaccines would be similar,” said the scientists, while stressing that long-term effects need to be studied.
The findings come as Israel administers booster shots after giving 58% of the population two doses of the Pfizer jab.
The United States is also set to offer booster shoots to increase antibody levels following concerns about declining effectiveness of both the Pfizer and Moderna vaccines.
The Oxford research found that protection is higher among those already infected with the virus.
The study examined two groups of more than 300,000 people aged over 18, first during the period dominated by the Alpha variant, which emerged in Kent, southeast England, and secondly from May, when the Delta variant has been dominant.
It confirmed that vaccines are less effective against Delta, which was first detected in India.
The AstraZeneca jab is the most widely offered in the United Kingdom, while those under 40 are offered Pfizer or Moderna due to concerns over blood clots. – AFP, August 19, 2021
