Sharply rising Covid-19 infection rates across the world have ignited a scientific and ethical debate about whether booster shots are needed to maintain protection against the virus.
This week, following a spike in cases linked to the Delta variant, Israel became the first country to offer boosters, authorising third doses of the BioNTech/Pfizer jab to adults with serious pre-existing medical conditions, Other countries are considering whether and when to follow suit.
But the science on if boosters are needed to provide long-term immunity against the Delta variant is so far inconclusive. And the World Health Organization has challenged the ethics of administering third shots, while billions of people in lower-income countries are still waiting for their first.
Rajiv Shah, president of the Rockefeller Foundation, said he expected that booster Covid shots will be necessary in the years to come as the virus continues to circulate, much like with influenza, for which annual revaccination is required.
“The task of vaccinating the world is not a one-time task,” he told the Financial Times, adding that revaccination “will be an endemic reality”.
But it is unclear whether boosters are needed now. Studies in May by Public Health England in the UK, where the Delta variant is dominant, found that two shots of the BioNTech/Pfizer shot were still 96 per cent effective at preventing hospitalisation. The research did identify a drop in protection against symptomatic infection with Delta, but only slight — 88 per cent effective compared to 93 per cent against the Alpha variant first identified in Kent.
The leading jab makers have all said full vaccination is expected to provide immunity for at least six to 12 months. This week, Johnson & Johnson said interim results showed its single-shot vaccine produced a strong immune response eight months after vaccination, including against the Delta variant.
Other studies, however, have suggested that the immune response generated by several of the current vaccines could be last longer. University of Washington researchers in June found that both Pfizer’s and Moderna’s mRNA vaccines produced “persistent” immunity, with a stronger response in people who had previously been infected with coronavirus and later received full vaccination.
“The reason for a booster would be . . . the emergence of a new variant to which the immune response from a vaccine no longer covers it,” said Michael Saag, associate dean of global health at the University of Alabama at Birmingham. “Right now I’m not seeing that,” he said, adding that the numbers of vaccinated people becoming seriously ill from Covid had not significantly increased.
The leading drug companies appear to be in favour of quick boosters, with Pfizer and Moderna pushing most vocally for the use of third shots.
Last week, Pfizer said it planned to apply for emergency use authorisation in August from the US Food and Drug Administration to give people a third dose. The announcement provoked an immediate reaction from the FDA and the Centers for Disease Control, which said, in a joint statement, that fully vaccinated individuals “do not need a booster shot at this time”. “[We are] prepared for booster doses if and when the science demonstrates that they are needed,” the agencies said.
The booster market presents a huge opportunity for the pharmaceutical industry, with analysts anticipating tens of billions of dollars in revenues for Moderna and Pfizer alone.
In the UK, the government’s joint committee on vaccination and immunisation, recently issued interim advice that millions of the most vulnerable people, especially the elderly, who tend to have weaker immune responses, should be revaccinated in the autumn. A final decision on whether to authorise the booster campaign will depend on the results of on going studies into the length of protection provided by the vaccines, the UK has said.
Azra Ghani, chair of infectious disease epidemiology at Imperial College London, said it was “pragmatic” for the UK to plan ahead given its plentiful supply of doses.
Two-thirds of the adult population in the UK has been fully vaccinated and the government is still expecting doses from its original procurement contracts with Novavax and Johnson & Johnson, in addition to extra Pfizer vaccines ordered earlier this year. The EU is similarly preparing to administer boosters, having ordered 1.8bn Pfizer doses to be delivered from the end of this year until 2023.
The EU has said it can donate any surplus. Still, Tedros Adhanom Ghebreyesus, director-general of the World Health Organization, this week slammed wealthy countries for ordering additional shots, while vast swaths of the developing world cannot even get hold of first doses.
“The global gap in Covid-19 vaccine supply is hugely uneven and inequitable,” Tedros said. “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.”
Nearly half of the US is fully vaccinated, compared to less than 2 per cent of the total population of Africa, according to the WHO.
“It really is ethically concerning,” said Michael Carome, director of the health research group at advocacy group Public Citizen. “The real focus should be on getting the vaccine out to the countries where they’re lagging well behind because ultimately that will protect everyone.”
Ghani, at Imperial College London, said the decision about whether to boost was ultimately a political balancing act.
For individual countries, “there’s really no harm giving out a booster dose”, she said. However globally, “those vaccines could likely save more lives if given as first and second doses to people who haven’t received them. And of course, that would have the benefit of reducing transmission and making this country safer”.