You may not need a Covid booster shot every year after all

As some governments and pharmaceutical officials prepare for Covid-19 booster shots targeting more infectious virus variants, health authorities say it’s too early to tell if they will be required.

“We do not have the information that’s necessary to make the recommendation on whether or not a booster will be needed,” said Soumya Swaminathan, the World Health Organisation’s (WHO) chief scientist. The “science is still evolving”.

Such a call is “premature” while high-risk individuals in most of the world haven’t yet completed a first course of vaccination, she said. Data from countries introducing precautionary extra inoculations later this year, particularly for vulnerable people whose immunity to SARS-CoV-2 may wane faster, will inform WHO’s guidance, Swaminathan added.

Covid-19 booster shots are likely to be rolled out in UK in autumn there to avoid another winter surge. Seven vaccines are being tested on volunteers in England in the world’s first booster study, the country’s health secretary, Matt Hancock, said last month.

The UK, which has inoculated a larger proportion of people than any other major economy, has been forced to delay a planned lifting of coronavirus restrictions amid a resurgence of cases driven by the Delta variant. The strain, first found in India, is the most infectious reported to date.

More transmissible variants, including the Beta strain that emerged in SA, require higher antibody levels to prevent infection, prompting vaccine makers, including Pfizer and Moderna, to test whether tweaked versions of their existing shots will provide broader immunity.

One dose of Novavax’s variant-directed vaccine may provide sufficient protection against the Beta strain in individuals previously immunised against Covid-19, according to preclinical research released this month by scientists at the company and the University of Maryland School of Medicine.

The modified shot also has the potential to provide broad protection against various strains if used as a primary vaccine regimen, said Gregory M Glenn, Novavax’s president of research and development, in a recent statement.

So far, the existing US-approved vaccines work well enough to protect against Beta, Delta and two other strains the WHO has designated as variants of concern, said Francis Collins, director of the US’s National Institutes of Health.

“Nobody is saying you need a booster today,” Collins said in an interview with biologist Lee Hood at the Precision Medicine World Conference in the US on Thursday. “But boosters might very well be in our future at some point and they might be here sooner if other variants pop up” that aren’t covered as well by existing vaccines.

As a minimum, vaccines will need to protect against hospitalisation, ICU admission and death, according to Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia. “With that bar, we probably would need a vaccine maybe every three to five years,” he said in a STAT biotech podcast on Thursday.

Immunisation with a combination of vaccinations may offer longer immunity or fewer side effects for certain individuals, he added.

Early data from the UK, Spain and Germany suggest a “mix and match” regimen using two different types of vaccines generates more pain, fever and other minor side effects compared with two doses of the same inoculation, Swaminathan said.

Still, the so-called heterologous prime-boost combinations appear to spur a more robust immune response, leading to higher levels of virus-blocking antibodies and the white blood cells that kill virus-infected cells, she said.

Combinations of the AstraZeneca and Pfizer shots are being considered in Malaysia, where the government is trying to speed up immunisations to achieve population-level immunity by the end of the year, science, technology and innovation minister Khairy Jamaluddin said on Wednesday.

“It seems to be working well, this concept of heterologous prime-boost,” Swaminathan said. “This opens up the opportunity for countries that have vaccinated people with one vaccine and now are waiting for the second dose they have run out of to potentially be able to use a different platform vaccine.”

— Bloomberg News. More stories like this are available on bloomberg.com