Booster shots are coming to the US. But the world's poorest are still waiting for their first

The US is expected to recommend a third shot to bolster immunity, a move the World Health Organization says will only widen global vaccine inequality.

US President Joe Biden's plan, expected to be discussed on Wednesday, would see booster shots rolled out in mid- to late September, one source told CNN, pending authorization from the US Food and Drug Administration (FDA). The news follows the recommendation last week by the US Centers for Disease Control and Prevention (CDC) that people with immunocompromised systems get an extra dose of the vaccine.Data from vaccine-maker Pfizer-BioNTech submitted to the FDA showed that the third dose elicited a significantly higher antibody response against the initial strain of the coronavirus, as well as against the Delta and Beta variants, compared with that seen following a two-dose course.But the FDA and CDC say there is no clear argument yet for giving boosters to people with normal immune systems, as data continues to show that the vaccines still protect against severe disease. As Delta surges across the US, nearly all of those becoming severely ill with the virus are unvaccinated. Public health experts aren't convinced, either. The answer to reducing deaths and hospitalizations, many say, is simple: Get unvaccinated people the shots first. Scott Hensley, an immunologist at the University of Pennsylvania, points to the fact that some 90 million eligible Americans remain unvaccinated -- and are the main vehicle for the virus' spread across the country. "Of course we want people to be protected and to receive the full course," he said. "But what we are trying to move against is giving a third dose to people who already are well protected." He added: "If you think a third dose of the vaccine is going to end the pandemic, then you are kidding yourself. The way to end this pandemic is to get the vaccine distributed across the globe." It's an argument the World Health Organization has been making for months. Fiercely opposed to the use of booster shots for now, WHO says the move will undoubtedly exacerbate vaccine inequality. Countries including Israel, Germany, France and the United Arab Emirates have already authorized booster shots for older adults. But only 1.3% of people in low-income countries have received at least one dose, according to Oxford University's Our World in Data. Andrew Pollard, director of the Oxford Vaccine Group at the University of Oxford, and Seth Berkley, chief executive of Gavi, the Vaccine Alliance, warned in an essay published by the Guardian on Friday that "large-scale boosting in one rich country would send a signal around the world that boosters are needed everywhere." They said: "This will suck many vaccine doses out of the system, and many more people will die because they never even had a chance to get a single dose." Meanwhile, in Afghanistan, the ongoing chaos in the wake of the Taliban takeover is taking a "heavy toll" on the country's "fragile health system," WHO Spokesperson Jarik Jašarević said Tuesday, with disruption at the airport delaying urgently needed health supplies, including Covid vaccines. Crowding at health facilities and internally displaced people's camps will further hamper infection prevention measures, he said.