Covid vaccine: Protection starts fading within six months
Protection against Covid-19 offered by two doses of the Pfizer/BioNTech and the Oxford/AstraZeneca vaccines begins to fade within six months, underscoring the need for booster shots, according to researchers in Britain.
After five to six months, the effectiveness of the Pfizer jab at preventing Covid-19 infection in the month after the second dose fell from 88% to 74%, an analysis of data collected in Britain's ZOE Covid study showed.
For the AstraZeneca vaccine, effectiveness fell from 77% to 67% after four to five months.
The study was based on data from more than a million app users, comparing self-reported infections in vaccinated participants with cases in an unvaccinated control group.
More data is needed in younger people because participants who had their shots up to six months ago tended to be elderly as that age group was prioritised when the shots were first approved, the study authors said.
ZOE Ltd was founded three years ago to offer customised nutritional advice based on test kits. The company's ZOE Covid Symptom Study app is a not-for-profit initiative in collaboration with King's College London and funded by the Department of Health and Social Care.
Under a worst-case future scenario, protection could fall below 50% for older people and healthcare workers by the winter, Tim Spector, ZOE Ltd co-founder and principal investigator for the study, said.
"It's bringing into focus this need for some action. We can't just sit by and see the protectiveness slowly waning whilst cases are still high and the chance of infection still high as well," Spector told BBC television.
Britain and other European nations are planning for a Covid-19 vaccine booster campaign later this year after top vaccine advisers said it might be necessary to give third shots to the elderly and most vulnerable from September.
"This is a reminder that we cannot rely on vaccines alone to prevent the spread of Covid," said Simon Clarke, Associate Professor in Cellular Microbiology at the University of Reading, who was not involved in the study.
'SHOCKING DISPARITY'
A separate British public health study found last week that protection from either the Pfizer-BioNTech or the AstraZeneca vaccine against the now prevalent Delta variant of the coronavirus weakens within three months.
The Oxford University study found at the time that 90 days after a second shot of the Pfizer or AstraZeneca vaccine, their efficacy in preventing infections had slipped to 75% and 61% respectively. That was down from 85% and 68%, respectively, seen two weeks after a second dose.
The US government is preparing to provide third booster doses starting in mid-September to Americans who had their initial course more than eight months ago.
The World Health Organization hit out on Tuesday at the "shocking disparity" in access to coronavirus vaccines, with only four countries in Africa able to meet their inoculation targets so far.
"Globally, 140 countries have vaccinated at least 10 percent of their populations," WHO chief Tedros Adhanom Ghebreyesus told the opening of an online meeting of African health ministers.
"But in our continent, only four countries have been able to reach that target, owing to the shocking disparity in access to vaccines."
The WHO secretary-general said that "the vaccine crisis illustrates the fundamental weakness at the root of the pandemic: the lack of global solidarity and sharing".
The Economist Intelligence Unit's study, released yesterday, found that the slow rollout of coronavirus vaccines will cost the global economy $2.3 trillion in lost output.
The study also said that emerging and developing economies, whose vaccine rollouts are far behind those of wealthier countries, will bear the brunt of those losses.
HOSPITALS BATTLE COVID
The coronavirus has killed at least 4,451,888 people since the outbreak emerged in China in December 2019, according to an AFP compilation of official data yesterday.
Sydney's Covid-19 infections hit a daily record yesterday, putting parts of the health system under pressure, officials said, calling for vaccinations to be stepped up to stem the tide of hospital admissions.
Despite two months of lockdowns in Sydney, New South Wales (NSW) state reported 919 new cases amid a growing Delta variant outbreak, taking Australia's daily case numbers to a new pandemic high just below 1,000, reports Reuters.
New Zealand recorded 62 new cases yesterday, taking the total number of infections in the latest outbreak to 210 as the government scrambled to scale up vaccinations amid growing criticism.
Indonesia is taking its vaccination drive to the sea as the world's biggest archipelago nation ramps up a bid to innoculate its huge population.
The navy has deployed 60 boats and warships to scour thousands of kilometres of coastline in the hunt for unvaccinated fishermen, from westernmost Sumatra to holiday island Bali and remote Papua.
China reopened a key terminal at the world's third-busiest cargo port yesterday, after a shutdown to control the coronavirus caused backlogs through supply chains -- but disruptions at a major airport are now sending transport costs soaring.
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