This article is part of our special report From vaccine race to marathon: What’s next for coping with COVID?.
For now, vaccines are capable of dealing with SARS-CoV-2 virus variants circulating in the world. But as new variants potentially emerge vaccines might need to be adapted to fight the new strains.
Scientists warn that vaccine developers and authorities need to be prepared to adjust their vaccines but also the regulatory framework needs to be set to allow fast decisions.
All viruses, including SARS-CoV-2, the virus that causes COVID-19, change over time.
While most changes have little to no impact on the virus’ properties some changes may affect the virus’s properties, such as how easily it spreads, the associated disease severity, or the performance of vaccines.
COVID vaccines currently authorised in the EU were developed under two platforms: mRNA and adenoviral vector vaccines.
So far the vaccines authorised in the EU seem to be managing to protect people from circulating variants.
“We can see that vaccines are still working against variants, but we have reduced efficacy against, for example, the Delta variant,” Camilla Foged, professor at the University of Copenhagen, told EURACTIV. Foged is leading a research group on Vaccine Design and Delivery at the Department of Pharmacy. She added that all the vaccines show slightly reduced efficacy, but are still very good at protecting against hospitalizations and deaths.
A Lancet study published on Monday (13 September) showed that vaccines remain highly effective against severe disease, including that from all the main viral variants.
Averaging the results reported from the observational studies, vaccinations had 95% efficacy against severe disease both from the delta variant and from the alpha variant, and over 80% efficacy at protecting against any infection from these variants.
“The virus can still mutate, we can have more variants in the future, that’s very likely,” said Foged. This, according to her, might result in lower vaccine protection.
How easily can they be adjusted?
Foged also said that for mRNA vaccines it is “relatively easy” to adapt to new variants. “I know that Pfizer is testing a vaccine against the Delta variant. But it won’t be approved in the near future,” she said.
There are other vaccine platforms lining up and the traditional ones – recombinant proteins and the whole virion inactivated vaccines – might be approved in the coming weeks and months.
However, it might take slightly longer to adjust them to new variants, if needed, said Adam Finn of the European Technical Advisory Group of Experts on Immunisation (ETAGE), who is also chair of paediatrics at the University of Bristol.
He told EURACTIV that mRNA and adenoviral vector vaccines “reformulated slightly quicker, all you need is the genetic sequence to start doing that”.
For Professor Foged, too, it will take longer to adapt protein-based vaccines to new various virus strains, “because you have to express a new protein”.
But adjustability is only one side of the coin. Another issue is how to deliver newly adjusted vaccines.
ETAGE’s Finn said that despite being able to make the first steps of reformulation faster when it comes to mRNA and adenoviral vector vaccines, since they are “new platforms” there still might be “some challenges of producing millions of billions of doses reliably, as they are less experienced of doing it”.
Foged pointed out that procedures to respond rapidly to changes in virus mutations need to be prepared. “It’s important for the authorities to make procedures so we can rapidly respond to new virus variants. And also for the companies to be able to quickly test vaccines against new areas,” she said.
Finn also pointed to how developers focused on the Beta variant in the spring while in summer everyone was concerned about Delta.
“So everyone was making the wrong variant vaccine, they’ve gone off in the wrong direction. And coming back around, and getting in the right direction, takes quite a lot of time. So it’s more strategic thinking than the practical aspects of making the new vaccine that is challenging at the moment,” Finn concluded.
Vaccines adapted to new strains might be a better booster
The Lancet study also highlighted that a booster vaccine developed to fight new strains of the virus might be a better option than using one of those already available.
“Even if new variants that can escape the current vaccines are going to evolve, they are most likely to do so from strains that have already become widely prevalent. Therefore, the effectiveness of boosters developed specifically to match potential newer variants could be greater and longer-lived than boosters using current vaccines,” stated a Lancet press release.
It added that a similar strategy is used for influenza vaccines, for which each annual vaccine is based on the most current data about circulating strains, increasing the likelihood that the vaccine will remain effective even if there is further strain evolution.
[Edited by Gerardo Fortuna and Benjamin Fox]