Could a single vaccine fend off all versions of COVID? Here’s where the science stands – San Francisco Chronicle

More than a year after they started going into arms, coronavirus vaccines are still working remarkably well, credited with saving millions of lives and keeping many more people from getting seriously sick.

But like some other vaccines, COVID-19 shots have a potential weakness. Without frequent boosters, they dont appear to provide long-lasting protection against infection caused by variants like omicron that have strayed far from the virus original genetic composition often called the Wuhan or ancestral strain, which the current vaccines were designed to target.

So, scientists are pushing to do even better. Ultimately, theyd like to develop a vaccine that would work against hundreds of different coronaviruses, including SARS 1 and 2, MERS and the versions that cause the common cold. A pan-coronavirus vaccine is considered a holy grail that many researchers believe may not happen for years or decades, if ever.

That would be absolutely wonderful, said Dr. John Swartzberg, a professor emeritus of vaccinology and infectious diseases at UC Berkeley School of Public Health. Weve been trying to do this for 30 years with influenza, ... But we havent been able to do that yet. I have every confidence in the world we will find it and it will work. I just dont know when.

A more realistic scenario, he said, would be to make second-generation COVID vaccines that cover a few more variants of SARS-CoV-2 than the current versions. Then, build on those to make third-generation vaccines that would cover a few more. And so on.

The idea is if a vaccine works against many relatives of the same genetic family now, itd also work at least in part against future relatives, even if scientists dont know yet what those are.

Much of this research is already under way. Vaccine manufacturers are testing formulations of their products that cover multiple variants, and some of these updated versions could come to fruition in coming months. One major National Institute of Allergy and Infectious Diseases trial started just last week at 24 U.S. sites to test various combinations of the current vaccine with others tailored to beta, delta and omicron. One of the locations is San Francisco General Hospital, which began recruiting volunteers Friday.

Even better, and one step closer to a pan-coronavirus vaccine, would be vaccines that work on many sarbecoviruses, a subset of coronaviruses that includes SARS 1 and 2, as well as others that originate in bats and pangolins.

Do we really need a variant-proof or a pan-coronavirus vaccine? The virus that causes COVID-19 will keep mutating, and we may need shots better tailored to target future variants if the goal is to prevent infections, which many say is secondary to preventing severe illness and deaths. The current vaccines, when followed by a booster, already do the latter quite well.

But looking beyond this pandemic, there is a good chance another coronavirus could transmit from animals to humans and once again cause global calamity. A pan-coronavirus vaccine could help contain that early.

Weve had three coronavirus epidemics in the last 20 years, said Dr. Drew Weissman, a leading vaccine researcher at the University of Pennsylvania Perelman School of Medicine, whos working on pan-coronavirus vaccines, referring to SARS, MERS, and COVID-19. That tells us were going to have more. We have no idea when or how severe. We can wait for the next one to appear and rush to make a new vaccine and shut the world down for a year and a half. Or we can make one now so its ready to go.

Weissmans lab is among at least half a dozen U.S. academic research institutions, biotech companies and groups of government scientists who are working on variations of such future-looking vaccines. At least one has begun human clinical trials, and several have found promising early results in monkey or mice studies. Many are focusing on the spike protein, the signature feature of coronaviruses, but some are also examining other parts of the virus that dont mutate as quickly.

Stanford immunologist Bali Pulendran is working with researchers at the University of Washington to develop a vaccine that protects against many variants of SARS-CoV-2. This could help pave the way for pan-sarbecovirus and ultimately pan-coronavirus vaccines.

In a study Pulendran and his Stanford colleague Prabhu Arunachalam conducted last year on monkeys, the vaccine when given with an adjuvant, a chemical that jump-starts the immune system elicited a strong immune response against the Wuhan strain and the alpha and beta variants.

The vaccine tested in that study is now in large phase 3 clinical trials. More recently, Pulendrans work shows that this vaccine elicits a strong and durable immune response against not just the Wuhan strain, beta and delta but also robust protection against omicron for at least six months.

Most researchers in this area are working with one of two vaccine technologies. One is mRNA, the same as that used by Pfizer and Moderna, where the idea is to take hybrid spike proteins from many different viruses and deliver them in a single shot, therefore protecting against all those viruses.

The other technology is a nanoparticle vaccine. The idea is analogous to a soccer ball, where each of the black pentagons can be linked with a spike protein from the virus. When the immune system sees the viral proteins in the nanoparticle, the immune response is really good, said David R. Martinez, an immunologist at the University of North Carolina whos developing an mRNA vaccine that could work against multiple coronaviruses.

Both approaches share the same goal to get the immune system to ramp up against what it thinks is a threat. But they go about it differently. The nanoparticle approach involves injecting patients directly with proteins seen by the immune system. They typically take longer to develop because the proteins must be made and purified in a lab. mRNA vaccines can skip this step because they essentially use the bodys cells to make proteins.

Walter Reed Army Institute of Research is considered to be one of furthest along in developing a nanoparticle vaccine that works against multiple coronaviruses. Researchers there started phase 1 human clinical trials in April 2021 for a pan-SARS vaccine that in early studies appeared to protect monkeys against SARS 2 and SARS 1. Its not clear when they expect to report results.

Its good to have multiple approaches because ultimately you dont know which one will be the most successful, so its important to have multiple of these things move forward, Martinez said. At the end of day you dont know which one will yield the best result.

Catherine Ho (she/her) is a San Francisco Chronicle staff writer. Email: cho@sfchronicle.com Twitter: @Cat_Ho

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Could a single vaccine fend off all versions of COVID? Here's where the science stands - San Francisco Chronicle