The World Health Organization called on Wednesday for a moratorium on coronavirus vaccine booster shots until the end of September, so that vaccine supplies can be focused on helping all countries vaccinate at least 10 percent of their populations. The agency made its appeal to the world’s wealthiest nations to address the wide disparities in vaccination rates around the world.
“I understand the concern of all governments to protect their people from the Delta variant,” Tedros Adhanom Ghebreyesus, director general of the W.H.O., said in a briefing. “But we cannot — and we should not — accept countries that have already used most of the global supply of vaccines using even more of it, while the world’s most vulnerable people remain unprotected.”
With the debate over booster shots heating up, the call highlighted a moral and scientific case long pressed by humanitarian groups: With the staggering gaps in vaccination rates around the world and cases surging as the Delta variant spreads, vaccine doses should be given first to vulnerable people in poorer nations. Fully vaccinated people are protected against the worst outcomes of Covid-19 caused by the Delta variant.
W.H.O. officials went to pains to distinguish between booster shots used to shore up immunity in vaccinated populations, for which the science is not yet clear, and additional doses that may be needed by the immunocompromised to develop immunity in the first place. Officials said they objected to boosters, not to additional doses for some subgroups.
Of more than four billion vaccine doses in total that have been administered around the world, more than 80 percent have been used in high- and upper-middle-income countries, which account for less than half of the world’s population, Dr. Tedros said.
“We need an urgent reversal, from the majority of vaccines going to high-income countries to the majority going to low-income countries,” he said.
Scientists have not reached a consensus on whether booster shots are needed to boost immunity in fully vaccinated people. Still, with worries mounting about continuing pandemic waves and future lockdowns, an increasing number of countries, like Germany, Israel and France, are preparing to offer booster doses to segments of their populations, or have already started administering them. Russia has made additional shots available to anyone six months after inoculation, and Hungary is offering them four months post-vaccination.
Studies have indicated that the immunity generated by the Pfizer-BioNTech and Moderna vaccines is long-lasting, and researchers are still working to understand recent Israeli data suggesting that the Pfizer-BioNTech vaccine declined in effectiveness months after inoculation. Pfizer has begun making a case for booster shots in the United States as well, and if third shots are cleared for the general population, the boosters would potentially represent a multi-billion-dollar business for Pfizer.
Asked about the W.H.O.’s call on Wednesday afternoon, Jen Psaki, the White House press secretary, said at a news conference, “We feel that it’s a false choice, and that we can do both.”
“We will have enough supply to ensure, if the F.D.A. decides that boosters are recommended for a portion of the population, to provide those as well,” Ms. Psaki added, noting efforts by the administration to send vaccine doses to other countries.
Deaths from Covid-19 have surged in African nations in recent months, while many health workers and elderly or vulnerable people in the region have remained entirely unprotected. Doctors Without Borders said recently that it would be “unconscionable” to give booster doses in richer nations before people in poorer ones get their first doses.
Dr. Anthony S. Fauci, the top infectious disease expert in the United States and an adviser to Mr. Biden, said on Tuesday that in some cases, it takes more than the usual number of shots to completely vaccinate immunocompromised people.
“Giving them an additional shot is almost not considered a booster, it’s considered part of what their original regimen should have been,” Dr. Fauci said in an interview with the Center for Strategic and International Studies. Many such patients, and “maybe most of them, have not gotten an adequate immune response to begin with,” he said.
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That point was echoed by Dr. Bruce Aylward, a senior W.H.O. adviser, who said at Wednesday’s briefing that for people like solid organ transplant patients, a third dose would be part of “their primary series” of treatment and not a booster.
The W.H.O.’s appeal largely put the onus of fixing the world’s vaccine gaps on the world’s wealthiest nations, saying that the leadership of Group of 20 countries would determine the course of the pandemic. Dr. Tedros asked health ministers of those countries, who are meeting ahead of a planned summit in October, to make “concrete commitments” to reach the organization’s global vaccination target.
Vaccine producers, he said, should give priority to supplying Covax, a U.N.- backed alliance that was supposed to ensure that poorer countries’ health workers and vulnerable residents were all inoculated.
But the program has struggled to acquire enough doses, and is half a billion short of its targets. Supplies have dried up from some of the manufacturers it was most relying on, leaving a number of its recipient countries nearly or entirely out of vaccines in recent months.
Wealthier nations have a clear incentive to fill vaccination gaps in a continuing crisis that has gripped every corner of the world: the longer the virus rampages, the more dangerous it can become, as new variants emerge that may endanger progress even in even largely vaccinated nations.
The pandemic will not end “unless the whole world gets out of it together,” Dr. Aylward said. “With the huge disparity in vaccination coverage, we are simply not going to achieve that.”