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       A sign indicates the way to a drive-thru COVID-19 vaccination centre outside an IKEA store in Berlin on July 29, 2021.

       STEFANIE LOOS/AFP

       As concerns grow over the more contagious delta variant of the coronavirus, Germany will offer vaccine booster shots to older people and people with underlying health conditions starting in September, according to a draft plan that is expected to be announced Monday.

       The move, amid increasing case numbers in the country, came after a top European Union official criticized the bloc as falling far short of its promises to donate vaccine doses to Africa and Latin America. And with a limited global vaccine supply, health experts say the priority should be inoculating high-risk people around the world.

       Scientists also still disagree on the need for booster shots.

       Under the German initiative, vaccination teams will be sent to care homes and other facilities for vulnerable people to administer Pfizer-BioNTech and Moderna shots, according to the draft plan. Doctors and vaccination centers will be called on to provide the extra shots for eligible people outside care homes.

       The guidelines cite studies that indicate “a reduced or quickly subsiding immune response after a full COVID-19 vaccination in certain groups of people,” notably those who because of age or preexisting conditions have weakened immune systems. The boosters will also be offered to people who received AstraZeneca or Johnson & Johnson shots initially.

       The issue of booster shots has been hotly debated in richer countries at a time when their rates of initial vaccinations have been slowing. But as the Delta variant has become dominant in much of the United States and Europe, more governments appear to be moving toward endorsing them.

       In the United States, Biden administration health officials increasingly think that vulnerable populations may need additional shots even as research continues into how long the vaccines remain effective. Israel, an early leader in administering vaccines, began administering boosters to people 60 and older last week.

       Opinion: Booster shots for Canadians are unlikely — for now

       The need for COVID-19 booster shots remains unclear. Studies have indicated that immunity resulting from the Pfizer-BioNTech and Moderna vaccines is long lasting, and researchers are still working to interpret recent Israeli data suggesting a decline in efficacy of the Pfizer-BioNTech vaccine months after inoculation.

       Pfizer, which has begun making a case for booster shots in the United States, offered its own study last week showing a marginal decline in efficacy against symptomatic infection months after immunization, although the vaccine remains powerfully effective against severe disease and death.

       Britain, which remains ahead of the European Union on vaccinations, has not yet formally announced plans for a booster shot program. But officials there have been planning for them ever since a committee of government advisers in late June outlined recommendations on how the shots could be administered.

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       Under those plans, health workers would begin administering booster shots in September, and people age 50 and older would be eligible. The committee said the priority would be getting the shots to people older than 70, health workers, nursing-home residents, and younger adults with immune problems or other serious vulnerabilities.

       It said that the plan would “maximize protection in those who are most vulnerable to serious COVID-19 ahead of the winter months,” when health officials fear that a coronavirus resurgence alongside other seasonal illnesses could put the health system under strain.

       Even as wealthier nations prepare to give booster shots, though, health experts say the focus should be on giving first doses to people in countries that remain largely unprotected, especially as the delta variant spreads.

       Doctors Without Borders said recently that it would be “unconscionable” to give booster doses in richer nations before people in poorer ones are protected.

       “Wealthy governments shouldn’t be prioritizing giving third doses when much of the developing world hasn’t even yet had the chance to get their first COVID-19 shots,” Kate Elder, the senior vaccines policy adviser at Doctors Without Borders’ Access Campaign, said in a statement.

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