What you need to know about the 2023 covid-19 vaccine boosters

Several countries, including the US, Canada and the UK, have approved new covid-19 booster vaccines, targeting a more recent variant than the boosters used last year. Here is what you need to know.

What exactly is in the new boosters?

The boosters, made by Moderna and Pfizer, consist of an mRNA recipe for making the spike protein of the XBB.1.5 variant of SARS-CoV-2. The spike protein protrudes from the surface of the virus and plays a part in infecting cells. Newer variants have changes in their spike protein that help them evade the antibodies we have to older variants. The boosters stimulate our immune systems to produce antibodies to the new versions of the spike protein.

Is the XBB.1.5 variant still around?

XBB.1.5 was chosen for the boosters because it was the main variant causing infections in June, when the vaccines needed to be finalised. It has already been largely replaced by yet more new variants, but most of these are closely related to XBB.1.5, so the boosters should still provide excellent protection.

Will the boosters protect against the new BA.2.86 variant?

BA.2.86 is an emerging variant with lots of changes in the spike protein, so there has been concern about the extent to which it can dodge the protection from vaccination or previous infections. However, an initial study released last week shows that the XBB boosters should work well against the BA.2.86 variant, too.

Why do the boosters no longer contain the original version of the SARS-CoV-2 virus?

Last year’s covid-19 boosters contained a mix of mRNA coding for the spike protein from the original virus and that of the BA.4 and BA.5 variants. Studies suggested that these bivalent boosters were less effective than they might have been because including the original strain tended to make the immune system rev up its previous response, instead of focusing more on the newer variants. So, this year’s boosters are monovalent, only containing mRNA for making the spike protein of the XBB.1.5 variant.

Who should get a covid-19 booster this autumn?

The recommendations vary from country to country. The US is recommending boosters for everyone over six months old, but most other countries are only targeting high risk groups, such as those over 65.

When will the boosters be available?

In the US, the 2023 boosters are becoming available from 18 September. In the UK, the National Health Service has begun contacting people who are eligible for a booster. However, people in the UK might get one of the bivalent boosters from last year instead of the new XBB one, because the plan is to use both. An older booster isn’t quite as good, but will still provide far more protection than no booster.

Can I get a flu vaccination at the same time as a covid-19 booster?

Yes. A study last year suggested that people’s reaction to having both can be slightly stronger, so you might feel a bit more tired or have a worse headache than if you had only one. But, on the plus side, you get it over and done with in one go.

What about RSV vaccines?

RSV, or respiratory syncytial virus, is a common virus that causes cold-like symptoms in most people, but can be deadly in the very young or very old. An RSV vaccine for people aged over 60 was approved in the US earlier this year for the first time and is now available in some countries.

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