Pfizer and Moderna's Covid-19 vaccines point the way to conquering the next coronavirus pandemic and may already offer some basic protection against killers such as MERS or other as yet undiscovered threats, according to new US research.
In experiments described by leading scientists as "exciting", researchers at Duke University tested mRNA vaccines that were very similar to the approved jabs on monkeys. They found that the vaccines induced antibodies that not only protected against Sars-CoV-2, the virus that causes Covid-19, but could also guard against other viruses from the same family.
"These results demonstrate current mRNA vaccines may provide some protection from future zoonotic betacoronavirus [coronaviruses crossing from animal to human] outbreaks, and provide a platform for further development of pan-betacoronavirus vaccines," the paper, published this week in Nature, concludes.
Sars-Cov-2 is already the third threatening coronavirus to arise this century, after the viruses causing MERS (Middle East respiratory syndrome) and SARS (Severe acute respiratory syndrome), and experts agree that another could easily take hold.
The team at Duke Human Vaccine Institute, led by Professor Kevin Saunders, also tested a new vaccine they have developed. It is a protein nanoparticle vaccine, which works slightly differently to the existing mRNA vaccines.
It showed even more potent cross-protection against other coronaviruses, including all known variants of Sars-CoV-2, bat coronaviruses and Sars-CoV-1, which causes Sars. This new vaccine also stopped viral replication in the nose, suggesting it could have a major impact on transmission.
Dr Anthony Fauci, America's top infectious disease expert, told a White House press briefing this week that there were "caveats" because the experiments were done with monkeys, not humans. But he added: "This is an extremely important proof of concept that we will be aggressively pursuing as we get into the development of human trials."
The new vaccine works by targeting a particular part of the virus, the receptor binding domain (RBD), which is a critical part of the spike protein that allows the virus to enter human cells.
It is also a part of the virus which is very stable - so it does not change - between the different variants or even between entirely different coronaviruses, which is why it appears to generate these "broadly neutralising antibodies" that could stop emerging pandemics in their tracks.
The reason that the Pfizer and Moderna jabs might work similarly, in terms of the antibody response at least, is that they target the entire spike protein of Sars-Cov-2, which includes the RBD.
Professor Saunders told The Telegraph: "We found that the nanoparticle vaccine generated a really potent antibody response against these different viruses. And we found that even if you get an mRNA vaccine, similar to what Pfizer and Moderna have made, your body will generate a similar type of response, but it is weaker."
The question now is how strong that response needs to be in order to provide protection, and whether the results in monkeys can be replicated in humans.
Prof Saunders said the nanoparticle vaccine, if it proves safe and effective in humans, could be a booster for the Pfizer and Moderna jabs if a new coronavirus threat emerges, or a vaccine in its own right.
It is unclear how long protection lasts from the existing crop of vaccines, so another option would be inoculating high-risk individuals with the existing mRNA Covid-19 vaccines again if a new virus emerges, in the hope that they provide some protection while tweaked vaccines can be developed.
Professor Danny Altmann, a British immunologist at Imperial College, London, who was not involved in the study, said: "It's an optimistic message from a very strong vaccines group that we’ve pretty much got the vaccines to get around not just this coronavirus, but also other relatives coming around the curve."
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