Since the search for a first anti-Covid vaccine propelled a new generation of sera, much work has gone into developing pan-coronavirus immunity with varying degrees 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.
The adaptation of existing vaccines to all existing strains – Pfizer announced a corresponding plan a few weeks ago – has a big limit in his eyes: “New variants will appear every three or six months”.
However, after more than two years of trying to infect more and more people, the virus is starting to purposefully mutate to bypass vaccine-acquired immunity — much like the flu’s constant mutations, which require a new serum every year, he explains.
“It complicates things a bit because we’re now 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 without them the virus would die.
But it won’t be easy. “We could have a universal vaccine in two or three years, but we will continue to work and adapt to stay ahead of the virus,” Drew Weissman said.
Covid-19 is not the first coronavirus to jump from animals to humans 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 company VBI Vaccines announced its pan-coronavirus project in the early days of the pandemic in March 2020, it targeted these three coronaviruses.
Thinking of each antigen of their vaccine as a primary color, these researchers hoped their vaccine would provide antibodies not only for those colors, but also for “the various shades of orange, green, and purple found between those colors.” describes Francisco Diaz-Mitoma, Chief Medical Officer of VBI.
“In other words, we’re trying to teach the immune system to expand the variations of the virus that it can ‘see’ from the start,” he says.
“One Step Forward”
VBI’s vaccine testing has been promising so far — including in bats and pangolins — and the biotech hopes to start clinical trials in the coming months, with 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, was funded by the National Institute of Allergy and Infectious Diseases.
This vaccine, which targets Sars-like viruses but not a broader spectrum 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, given the multitude of strains, including those from the common cold, a true universal vaccine against the coronavirus is probably not realistic.
His project uses a mosaic nanoparticle strategy to target the B lineage of betacoronaviruses, which include the original Sars-CoV and Sars-CoV-2, the cause of Covid-19.
Even this “search” for a specific lineage is comparable to the “long-term effort to create a universal flu vaccine,” she points out. Like Barton Haynes, she believes it is crucial that human clinical trials begin quickly in order to have a vaccine widely available.
Although none of the current pan-coronavirus vaccine projects are expected to be rolled out over the next year, their arrival could change the global approach to Covid.
“Overall, if a pan-coronavirus vaccine succeeds in conferring broader immunity against coronaviruses, it would allow us to go from stepping backwards to stepping forward on the pandemic,” said Francisco Diaz-Mitoma.
And by broadening the horizons for vaccine research, Covid may have pushed the world to better prepare for the threat of future, potentially worse, pandemics.