A new study has found that effectiveness of the Pfizer vaccine declines faster than AstraZeneca.
A new study shows that the effectiveness of Pfizer wears off faster than AstraZeneca.
The effectiveness of the Pfizer-BioNTech vaccine against Covid-19 declines faster than that of the AstraZeneca jab, according to a new study published on Thursday.
“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,” researchers at Oxford University said.
The study, which has not been peer reviewed, is based on the results of a survey by Britain’s Office for National Statistics that carried out PCR tests from December last year to this month on randomly selected households.
It found that “the dynamics of immunity following second doses differed significantly” between Pfizer and AstraZeneca, according to the university’s Nuffield Department of Medicine.
Pfizer had “greater initial effectiveness” but saw “faster declines in protection against high viral burden and symptomatic infection”, when looking at a period of several months after full vaccination, although rates remained low for both jabs.
“Results suggest that after four to five months effectiveness of these two vaccines would be similar,” the scientists added, while stressing that long-term effects need to be studied.
A medic holds up a vial of the Pfizer vaccine in Taibeh, Israel.
The study’s findings come as Israel is administering booster shots, after giving 58 per cent of the population two shots of the Pfizer jab.
The United States is also set to offer booster vaccines to boost antibody levels following concerns over declining effectiveness of the Pfizer and Moderna vaccines.
The Oxford research also found that protection was higher among those who had already been infected with the virus.
The study examined two groups of more than 300,000 people over 18, first during the period dominated by the Alpha variant, which emerged in Kent, southeast England, and secondly from May 2021 onwards, when the Delta variant has been dominant.
It confirmed that vaccines are less effective against Delta, which was first seen in India.
The AstraZeneca vaccine is the most widely offered in the UK, while those under 40 are offered Pfizer or Moderna due to blood clotting concerns.
An Israeli health worker prepares to administer a third dose of Pfizer.
Booster shots in Israel
Israelis aged 40 and over will be able to receive coronavirus vaccine booster shots starting this weekend, Health Minister Nitzan Horowitz said on Thursday, as the country battles a spike in infections.
Israel was one of the first countries to launch a vaccination drive in mid-December via an agreement with Pfizer to obtain millions of paid vaccine doses in exchange for sharing data on their effectiveness.
The inoculation campaign was hailed as a success story that helped drastically reduce infections in the country of nine million.
But cases have been rising due to the spread of the Delta variant among the unvaccinated and waning immunity in others.
Israelis aged 40 and over will be able to receive booster shots starting this weekend.
To try and contain the spread, authorities last week began administrating a booster shot to those aged 50 and older, after starting a campaign for over-60s late last month.
Horowitz, who is among those who have received a third dose, tweeted Thursday that people aged 40 and over will be able to get a booster shot from Sunday.
“We have vaccines for everyone and now those 40 and older can receive a third dose,” he wrote. “The vaccine is effective. Let’s stop this Delta.” Israel has recorded more than 970,000 coronavirus infections since the pandemic started early last year, and over 6,700 deaths.
More than 5.4 million people have received two doses of the vaccine, while 1.2 million have had a third jab.
Earlier this month, the World Health Organisation called for a moratorium on Covid-19 vaccine booster shots to help ease the drastic inequity in dose distribution between rich and poor nations.