As people in wealthy nations snap up booster shots amid the rapid spread of the Omicron variant, the World Health Organization’s leader warned that universal access to extra doses in highly inoculated countries could worsen global vaccine inequality and prolong the pandemic.
That imbalance, Tedros Adhanom Ghebreyesus, the W.H.O.’s director-general, said on Wednesday, will give “the virus more opportunity to spread and mutate.”
“It’s important to remember,” he said, “that the vast majority of hospitalizations and deaths are in unvaccinated people, not unboosted people.” Later, he added: “No country can boost its way out of the pandemic.”
Since Covid vaccines were developed about a year ago, rich countries have had greater access to them despite global efforts to shrink that disparity. About 73 percent of shots that have gone into arms worldwide have been administered in high- and upper-middle-income countries, according to a New York Times tracker. Only 0.9 percent of doses have been administered in low-income countries.
“It’s frankly difficult to understand how a year since the first vaccines were administered, three in four health workers in Africa remain unvaccinated,” Mr. Ghebreyesus said.
He did not criticize specific countries by name on Wednesday but did say that “there is no doubt that the inequitable sharing of those vaccines has caused many lives” and questioned “why some countries are now rolling out blanket booster programs.”
Governments in Europe and elsewhere are accelerating booster shots as the scientific evidence accumulates that two vaccine doses are insufficient to stop infection from the highly transmissible Omicron variant, though the vaccines appear to reduce the risk of hospitalization and serious illness. Some public health experts who had opposed a boosters-for-all approach have changed their minds since the variant emerged.
This week, Israeli leaders said they would offer a fourth round of vaccines to people over 60 and to medical workers. France has shortened the wait before people can receive a booster shot to four months, from five. Britain will offer all eligible adults booster shots by the end of the year, a month earlier than planned.
And in the United States, where health officials have recommended booster shots for all adults, the Omicron variant is motivating more than half of vaccinated adults to get a booster shot, according to a recent poll by the Kaiser Family Foundation.
Although health officials and epidemiologists are urging Americans to get vaccinated and boosted, however, the going has been slow. Just over half of Americans 65 and older — the population most vulnerable to a severe outcome from the virus — have received a booster.
Public health experts worry that socioeconomic disparities in U.S. vaccination rates will be exacerbated as booster shots roll out. Difficulty in taking time off work and disconnection from health care systems have contributed to a persistent gap in vaccination rates between the most and least socioeconomically vulnerable counties.
Looking ahead to the holiday celebrations, Mr. Ghebreyesus warned that people who have received booster shots should not rely on them as a substitute for other safety measures like wearing masks and avoiding crowded indoor gatherings.
“Boosters cannot be seen as a ticket to go ahead with the planned celebrations without the need for other precautions,” he said, adding that the new year “must be the end of the Covid pandemic” as well as “the beginning of something else: a new era of solidarity.”