Big drop in antibodies
A study of 614 fully vaccinated health workers in India found a "significant" drop in their Covid-fighting antibodies within four months of the first shot.
The findings could help the Indian government decide whether to provide booster doses as some Western countries have done.
Waning antibodies do not necessarily mean that immunised people lose their ability to counter the disease, as the body's memory cells may still kick in to offer substantial protection, said the director of a state-run institute that did the study.
"After six months, we should be able to tell you more clearly whether and when a booster would be needed," Sanghamitra Pati of the Regional Medical Research Centre, based in the eastern city of Bhubaneswar, told Reuters yesterday.
"And we would urge similar studies in different areas for pan-India data."
British researchers said last month that protection offered by two doses of the Pfizer/BioNTech and the AstraZeneca vaccines begins to fade within six months.
The Indian study, published in the Research Square pre-print platform but yet to be peer reviewed, is one of the first such done in the country involving its main two vaccines - Covishield, a licensed version of the AstraZeneca shot, and domestically developed Covaxin.
Health officials say though they are studying the evolving science on booster doses, the priority is to fully immunise India's 944 million adults. More than 60% of them have received at least one dose and 19% the required two doses.
Covid cases and deaths in India have come down sharply since a peak of more than 400,000 infections in early May. India has reported 33.29 million cases in total and 443,213 deaths.
The coronavirus has killed at least 4,636,530 people since the outbreak emerged in China in December 2019, according to an AFP compilation of official data yesterday.
NEW CLUSTER IN CHINA
Southern Chinese cities closed schools and ordered testing for millions yesterday in a race to curb a new Covid-19 outbreak which has sparked concerns over infections among unvaccinated schoolchildren.
Putian, a city of 3.2 million in coastal Fujian province, ordered testing of all residents after Delta variant cases linked to a returnee from Singapore ballooned into a province-wide outbreak of more than 100 people.
China reported 59 new domestically transmitted cases yesterday, up from 22 the day before, all in Fujian province.
British health officials yesterday recommended all vulnerable people, frontline health staff and those aged over 50 be offered a booster shot.
The Joint Committee on Vaccination and Immunisation's recommendation of a third dose six months after a second shot, paves the way for a broad revaccination programme in Britain, which has one of the world's highest death tolls from Covid-19.
It comes ahead of an announcement by the government on its strategy for taming infections this winter, with Prime Minister Boris Johnson and other officials warning that the battle against the virus was not over.
Covid-19 cases in the Australian city Sydney rose at the slowest pace in nearly two weeks yesterday, but officials said they needed to see a steady drop in daily cases before deciding whether infections had peaked after 12 weeks in lockdown.
New South Wales (NSW) state reported 1,127 new local cases, the majority in state capital Sydney, down from 1,257 on Monday. Two deaths were reported.
The Philippines will ease coronavirus restrictions in the capital Manila to spur economic activity, officials said yesterday, despite record infection numbers and a warning from the WHO against the move.
Restaurants, churches and beauty salons in the national capital region will open at lower capacities from Thursday to get tens of thousands more people back to work.
"We should strive for total health and this can only be realised by carefully balancing our Covid-19 response by considering both the health of our people and the economic health of the nation," President Rodrigo Duterte's spokesman Harry Roque said.