Booster shots ‘make a mockery of vaccine equity,’ the W.H.O.’s Africa director says.

NAIROBI, Kenya — The Africa director at the World Health Organization, Dr. Matshidiso Moeti, criticized the decisions by some wealthy nations to start administering coronavirus booster shots, saying the decisions “make a mockery of vaccine equity” when the African continent is still struggling to get vaccine supplies.

African countries continue to lag far behind other continents in inoculations, with only 2 percent of the continent’s 1.3 billion people fully vaccinated against Covid-19 so far. Though vaccine shipments have accelerated in recent weeks, African nations are still not getting nearly enough to meet their needs, Dr. Moeti said.

Instead of offering additional doses to their already fully vaccinated citizens, she said, rich countries should give priority to poor nations, some of which are being ravaged by the coronavirus pandemic.

“Moves by some countries globally to introduce booster shots threaten the promise of a brighter tomorrow for Africa,” Dr. Moeti said in an online news conference on Thursday. “As some richer countries hoard vaccines, they make a mockery of vaccine equity.”

The World Health Organization has called for a moratorium on booster shots until the end of September to free up vaccine supplies for low-income nations. But several wealthy nations have said they would not wait that long. In the United States, the Biden administration said on Wednesday that it would provide booster shots to most Americans beginning as soon as Sept. 20. France and Germany also said they plan to offer shots to vulnerable populations, and Israel has already given third shots to more than a million residents.

President Biden said in a television interview broadcast on Thursday that he and his wife, Jill Biden, plan to get booster shots themselves, assuming federal regulators give the go-ahead.

Mr. Biden defended offering Americans an additional shot when many countries were struggling to deliver initial doses to their populations.

“We’re providing more to the rest of the world than all the rest of the world combined,” Mr. Biden said in the interview on ABC. “We’re keeping our part of the bargain.”

Africa has so far reported more than 7.3 million cases and 184,000 deaths from the coronavirus, according to the W.H.O. The virus is now surging in about two dozen African nations, pushing many governments to impose lockdowns, extend overnight curfews, close schools and limit public gatherings.

Health experts say the more contagious Delta variant, first detected in India, is responsible for most of the current spread on the continent. “While it took eight months for Alpha to spread to 30 countries, Delta has done so in half that time — only four months,” Dr. Moeti said, comparing Delta to a variant first detected in Britain.

Several African countries are also dealing with outbreaks of other diseases. This week, Ivory Coast confirmed its first Ebola case in almost 30 years. Guinea reported a case of the Marburg virus, the first ever found in West Africa. Uganda, which just emerged from a 42-day coronavirus lockdown, announced a polio outbreak.

Dr. Moeti urged wealthy nations to “rethink the idea of boosters” because of the danger that more dangerous variants will arise as the virus spreads in unvaccinated populations.

“Failure to vaccinate the most at-risk groups in all countries will result in needless deaths,” she said. “We say this every week, and it cannot be repeated enough.”

Michael D. Shear contributed reporting.