In late May, the European Medicines Agency (EMA) recommended updating Covid-19 vaccines for 2026/2027 to target a variant known as XFG. The regulator’s Emergency Task Force said this strain, which is linked to the Omicron subvariant, has been circulating widely since at least the summer of 2025.
Background reading
Now, manufacturers of the four Covid vaccines approved in the EU are working to update their products. A similar process is in place for seasonal flu vaccines – although influenza virus strains are selected much earlier, in February rather than May.
Six years since the WHO declared Covid-19 to be a global pandemic, experts are exploring how Covid vaccination can best protect the public and health systems in the years to come.
We spoke to Professor Jonathan Van Tam, Emeritus Professor of the University of Nottingham, and a former Deputy Chief Medical Officer for England, about the future of Covid-19 vaccination.
Vaccines Today: The pandemic is officially over, but Covid-19 continues to spread. How can Covid-19 vaccination programmes be improved?
Professor Van Tam: We’re in a period of transition from the end of an emergency period to business-as-usual. While it’s clear that Covid-19 is no longer an emergency, and hasn’t been since 2022, it continues to pose increased danger to the elderly and people with certain underlying health conditions. Despite the risk of hospitalisation in those groups, uptake of Covid-19 booster vaccines is significantly lower than uptake of flu vaccines.
How do independent regulators decide which strains or families of viruses to prioritise in the COVID-19 vaccine?
Experts look at the circulating strains, disease activity, laboratory data, and vaccine effectiveness, where possible. This helps to determine whether current vaccines should be updated to cover newer strains that have emerged.
Compared to the well-established battle rhythm of selecting flu virus strains for the annual vaccination, there is still some work to do to fully embed SARS-CoV-2 in the WHO’s surveillance system.
For flu, strains are updated in February, with vaccines ready for the autumn. The process is not as settled yet for Covid, and in my opinion, happens too late in the year.
Why are the strains revised every year for flu and Covid?
The flu virus changes so fast that even if you had very long-lasting protection from the flu vaccine, you’d still have to change at least one of the vaccine strains annually because new ones come along which can be quite different year on year.
But what we’re seeing with SARS-CoV-2 [which causes Covid] is that although the strains have, in the past, changed quite fast, it’s an open question if they will continue to change at the same rate.
Many adults will have had two initial doses of vaccine and a booster shot during the emergency phase of the pandemic. Technical advisory committees, such as the JCVI in the UK and STIKO in Germany, currently recommend boosters only for those in risk groups and the elderly. That’s because healthy younger adults appear to be well protected against hospitalisation thanks to their earlier doses of vaccine.
Is Covid seasonal, with peaks in winter like flu or RSV?
Covid doesn’t have the same predictability as flu in terms of seasonality or in terms of how the virus changes. Flu is really visible every winter, with peaks between December and March in most European countries. Covid doesn’t work like that – it’s more like an undulating signal year round and the peaks are much more unpredictable.
Is it essential that the Covid vaccine is well ‘matched’ to the circulating strains?
New strains pop up through the year so by the time updated vaccines are available, there may be even newer strains in circulation. We’re always chasing the comet’s tail.
There are some signals that it may not be so important to have the very latest strains included in the Covid vaccine – rather more that a strain which is considered ‘fairly recent’ will be fine. In my personal view, we could say that all the currently approved vaccines are going to offer some protection against serious illness even as new variants emerge.
More generally, I am not yet convinced that we’ve settled on the optimal long-term use of Covid vaccines. I’d like to see more research, for example, on optimising protection by using different types of vaccines in an alternating cycle.
How might alternating the type of vaccine help?
We need more data on this but, because different vaccines stimulate the immune system in slightly different ways, it’s worth exploring whether this approach in the end offers broader protection, and it might also be longer lasting.
Think of it like training. Vaccines effectively train your immune system to fight off a real threat further down the line. If you go to the gym to do the same training regime every day, you’ll get broadly the same results. But if you mix up your routine, incorporating a combination of different exercises, slightly different muscle groups, you get better overall strength and conditioning. The question is whether the same is true of vaccination if we alternate vaccine types.
Although Covid and flu outbreaks are out of sync, are there benefits to aligning the timing of how the vaccines are updated and offered to the public?
Yes. There’s no particular logic to choosing Covid strains in May or June. There is an argument to pull it [Covid strain selection] back to the rhythm of flu vaccine strain selection.
At the delivery end, many healthcare professionals and national authorities are moving towards the idea that Covid and flu are given in the same visit.
Might this be more acceptable to the public?
The last time I had a Covid vaccine, I had the flu jab in the other arm 20 minutes later. The data are clear to me; I would still respond well to both vaccines. By making it more convenient for people to have both at the same time, we may address the disparity between relatively high flu vaccine uptake and much lower Covid uptake in almost the same target groups.
Beyond that, we could even look ahead to the possibility of having combined respiratory vaccines. Not just for flu and Covid, but potentially flu and RSV or other combinations. That’s one for the future, but if it makes it more convenient for patients, there may be benefits in terms of uptake.
We should be thinking now about whether the flu and Covid vaccine strains could be chosen at the same time, with a view to inviting eligible patients to a single appointment in the autumn.
