Marco Cavaleri, the head of vaccines strategy for the European Medicines Agency (EMA), has encouraged vaccine developers to “explore the feasibility” of making multivalent vaccines: those that cross-neutralise COVID-19 virus variants.
At Tuesday’s (January 18) EMA press briefing, Cavaleri said that it’s important “not to exclude any options […] in order to have a portfolio of options that later can be taken as the basis for the decision on which vaccine to put on the market”.
Multivalent COVID-19 vaccines could protect against several variants at once, as they would contain antigens from different COVID-19 virus variants of concern. Bivalent vaccines would function similarly, just against only two variants.
Following the outbreak of the Omicron variant, vaccine developers focused their efforts on a monovalent variant vaccine – a vaccine that targets only this variant of concern. At the briefing, Cavaleri described this as “the obvious option”.
“At the same time, we would like to have a more of a reflection around what else could be considered at this point in time”, he added. “Companies should explore the feasibility of developing bivalent or multivalent variant vaccines.”
He explained that the next step is “to determine if they would offer advantages to monovalent vaccines in terms of ability to cross neutralise other variants of concern”.
The idea of experimenting with vaccines that target several virus variants was raised during Wednesday’s meeting of the International Coalition of Medicine Regulatory Authorities (ICMRA).
The Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) established by the World Health Organisation (WHO) has also voiced interest in the development of multivalent vaccines.
In a WHO statement on COVID-19 vaccines, the group “encourages vaccine developers to gather data on a small scale on the breadth and magnitude of immune response for monovalent and multivalent vaccines against VOCs – this data would then be considered in a broader decision-making framework.”
The multivalent vaccine request for vaccine developers comes as medicine regulators strive to set up a long-term strategy against COVID-19, for which repeated boosters don’t seem to be the silver bullet.
Re-boosting is not efficient
Cavaleri said that ICMRA members agreed that “from a global perspective, the administration of multiple booster doses at short intervals will not be sustainable in the longer term”.
He described how it’s not only “challenging from the operational perspective” to run vaccination campaigns repeated times per year, but the lack of prior experience dealing with other diseases with this approach would make it “difficult to predict its impact overall”.
“Repeated administration of boosters with very short interval may reduce the level of antibodies,” he said, however he voiced concerns that this could potentially result in the vaccinations becoming less efficient over time.
He added that in case repeated revaccination will be needed in the future for all or for some groups, as immunosuppressed or older people, “it could be desirable to synchronise the vaccinations with the arrival of the cold season, similarly to what is done for influenza, so to increase the antibody response right at the time when is most needed”.
[Edited by Nathalie Weatherald]