There is an emerging debate over COVID-19 booster shots. It’s not just about whether and when these extra vaccine doses will become necessary, but also about basic ethics.

That’s because, while rich countries are now talking about moving to a flu-style system of regular boosters, most of the world is still experiencing a huge shortage of vaccines.

Nearly a quarter of the world’s people have received at least one dose of a COVID vaccine, but distribution has been anything but equal. A whopping 85% of vaccine doses have been administered in high- and upper-middle-income countries, whose financial resources allowed them to muscle their way to the front of the queue. But low-income countries have been left with 0.3% of total doses.

So, while the U.S. has fully vaccinated 48% of its population, and Europe is now swimming in vaccines, poorer countries are still barely off the starting blocks. “Rich countries are hoarding vaccines,” complained Bangladeshi Foreign Minister A.K. Abdul Momen, whose country has fully vaccinated 2.6% of its population, a few weeks ago. “They have several times more vaccines than they need.”

He’s not wrong. The EU has secured 6.6 doses for each person through 2023. With the union being on track to vaccinate 70% of its adults by the end of July, most of that is boosters.

“Look back in shame”

The World Health Organization is blunt about the implications, and wants rich countries to send their extra doses to the rest of the world rather than talking about boosters.

“The global gap in COVID-19 vaccine supply is hugely uneven and inequitable. Some countries and regions are actually ordering millions of booster doses, before other countries have had supplies to vaccinate their health workers and most vulnerable,” said WHO Director-General Tedros Adhanom Ghebreyesus on July 12.

While Tedros noted how the Delta variant of the coronavirus is “steadily putting pressure back on health systems,” even in countries with high vaccination coverage, he added that “in countries with low vaccine coverage, the situation is particularly bad. Delta and other highly transmissible variants are driving catastrophic waves of COVID-19 cases, which are translating into high numbers of hospitalizations and death.”

“I ask you, who would put firefighters on the front line without protection?” Tedros continued. “Who are the most vulnerable to the flames of the COVID-19 pandemic? The health workers on the front lines, older persons, and the vulnerable. We are making conscious choices right now not to protect those most in need; our own firefighters.”

Mike Ryan, the WHO’s emergencies program chief, put it even more starkly, saying the world will “look back in anger, and we will look back in shame” if countries start rolling out boosters in the near-term. “These are people who want to have their cake and eat it, and then they want to make some more cake and eat it too.”

Morality aside, the practical aspect of this is that, while the virus is allowed to circulate through unprotected people, there is a greater likelihood of it mutating and causing chaos even in richer countries—an effect we’re already seeing with the Delta variant, first identified in India, leading to the sudden rollback of reopenings in Europe.

Waning immunity debate

Yet it is these variants that boosters are in part designed to address—even before the drugmakers release newly tweaked versions of their vaccines that specifically target the new strains, as happens with the annual flu jab.

Thanks to Delta, countries such as Thailand and the UAE are already offering third doses to some people who have received full regimens of Sinovac, [hotlink]Sinopharm,[/hotlink] and AstraZeneca vaccines.

Even with Pfizer/BioNTech’s and Moderna’s more effective messenger-RNA (mRNA) vaccines, the manufacturers have been talking up the need for a booster.

The Delta variant has caused infection surges even in places that have high vaccination rates, notably Israel, whose vaccination campaign has leaned heavily on Pfizer/BioNTech. Pfizer interprets this as evidence of waning antibodies, and is now asking U.S. drug regulators to approve a booster that would be given as soon as six months after the initial vaccination—even though the data supporting its push comes from a study involving fewer than two dozen people.

“We are confident that such a boost will be highly effective against the Delta variant,” Pfizer research head Mikael Dolsten said last week.

But even in Israel, which has started giving third shots of the Pfizer/BioNTech vaccine to severely vulnerable people, officials are playing it cautiously. Ran Balicer, a top adviser to the health ministry, pointed out on July 12 that there is still no “clear evidence on waning immunity” and said “other potential explanations to some of the rising current cases” would need to be ruled out before deploying boosters more widely.

U.S. officials also want to see more evidence of the need for boosters before authorizing them, the New York Times reported on July 12.

“Based on the totality of the data they have to date, Pfizer and BioNTech believe that a third dose may be beneficial to maintain the highest levels of protection,” the companies said in a statement last week.

A Pfizer spokesperson added on July 13: “We are actively working with governments all around the world as well as global health partners to work towards fair and equitable access to COVID-19 vaccines while also providing our expertise and resources for novel approaches that can help to strengthen health care systems where greater support may be needed.”