Since the quest for a first anti-covid vaccine boosted a new generation of serums, a great deal of work has sought to develop pan-coronavirus immunity, with varying levels of ambition.
Drew Weissman of the University of Pennsylvania, one of the pioneers of messenger RNA technology used in Pfizer’s vaccine, is leading one such project.
In his eyes, the adaptation of existing vaccines to all existing strains – Pfizer announced a plan to this effect a few weeks ago – has a major limit: “New variants will appear every three or six months”.
However, after more than two years of trying to infect more and more humans, the virus is beginning to mutate specifically to circumvent the immunity acquired through vaccines – in the same way as the constant mutations of the flu, which require a serum changed every year, he explains.
“It complicates things a bit because now we are fighting the virus head-on,” summarizes Drew Weissman.
His team is therefore working on a universal anti-coronavirus vaccine. She is trying to find “very well-preserved epitope (antigenic determinant) sequences” – whole virus fragments that cannot easily mutate because the virus would die without them.
But it won’t be easy. “We could have a universal vaccine in two or three years, but we will continue to work on it and adapt to stay one step ahead of the virus”, describes Drew Weissman.
Covid-19 is not the first coronavirus to jump from animals to humans in this century: its oldest relative, Sars, killed nearly 800 people in 2002-2004, and Mers-CoV (Respiratory Syndrome Coronavirus of the Middle East) followed, in 2012.
When the American biotech VBI Vaccines announced its pan-coronavirus project in the early days of the pandemic, in March 2020, it was targeting these three coronaviruses.
If one imagined each antigen of their vaccine as a primary color, these researchers hoped that their vaccine would provide antibodies not only for these colors but also for “the different shades of orange, green and purple found between these colors” , describes Francisco Diaz-Mitoma, chief medical officer of VBI.
“In other words, we are trying to teach the immune system to expand on the variations of the virus that it is able to ‘see’ from the start,” he says.
” One step forward “
VBI’s vaccine tests have so far been promising – including on bats and pangolins – and the biotech hopes to start clinical studies in the coming months for results in early 2023.
Another project, using ferritin nanoparticles, led by Barton Haynes, director of the Institute for Human Vaccines at Duke University, in the United States, has received funding from the National Institute of Allergy and Infectious Diseases .
This vaccine, which targets Sars-like viruses but not a wider range of Mers-like coronaviruses, has been shown to be effective against Omicron, according to Barton Haynes.
For Pamela Bjorkman, of the California Institute of Technology, a true universal vaccine against the coronavirus is probably not realistic given the multiplicity of strains – among which those of simple colds.
His project uses a mosaic nanoparticle strategy to target the B lineage of betacoronaviruses, which includes the original Sars-CoV and Sars-CoV-2, the cause of covid-19.
Even this “quest” for a specific lineage is comparable to the “many years of effort to make a universal flu vaccine,” she points out. Like Barton Haynes, she believes that getting human clinical trials started quickly is crucial to having a vaccine widely available.
While none of the current pan-coronavirus vaccine projects are expected to roll out next year, their arrival could change the global approach to covid.
“If a pan-coronavirus vaccine succeeds in giving broader immunity against coronaviruses, it would allow us, overall, to move from a step back to a step forward on the pandemic”, according to Francisco Diaz-Mitoma.
And, by broadening the horizon for vaccine research, covid may have pushed the world to better prepare for the threat of future, possibly even worse, pandemics.