I think people are paying more and more attention to vaccines that can be used to prevent different variants of a disease. For instance, we update our seasonal flu vaccines on a yearly basis, but it would be nice to have one vaccine that can help protect us against different influenza strains. The same goes for SARS-CoV-2.
“These universal vaccines are relatively difficult to make because viruses mutate all the time and we never know what mutation they are going to present to us.”
Taking SARS-CoV-2 for instance, from the original strain all the way to the Delta variant, there was only a small number of mutations occurring in the spike protein. Then came the Omicron variant, which I think completely shattered people’s views of a virus’ mutation capacity. Because viruses are so volatile, it is difficult to develop universal vaccines or broad-spectrum antiviral therapeutics. For SARS-CoV-2, an antibody can have a good effect on one particular strain, but when mutations occur, the epitopes at which the antibody binds to the virus protein are partially or completely destroyed, making the antibody less effective or completely ineffective.
“It’s a challenging process, but I think at least in terms of the universal vaccine front, we [have] some encouraging news.”
I think just last year, the FDA started a clinical trial for a form of a universal flu vaccine which could be quite promising. I believe it’s derived from the H1N1 formula, into which they graft the hemagglutinin protein of different strains. With one injection, people could develop antibodies against the different influenza strains.
I would say this breakthrough is only the first step. I think in the future, there will be more and more different types or formats of universal vaccines available to the public or under development. The mRNA platform is relatively new and has been proven to be quite effective in terms of vaccine development, and fast as well. I think with this technology and also with the more conventional recombinant subunit vaccine approach, we might be able to have a format of a universal vaccine against influenza or coronaviruses in the future.
In terms of these broad-spectrum antiviral therapeutics, viruses may mutate a lot, but they do have some key regimens in their genome or proteome that cannot be replaced. For instance, their RNA polymerase or proteases are relatively stable in terms of their mutation rates. I think scientists are now developing antiviral therapeutics against these more conserved targets. In the future, there might be either small molecules or antiviral therapeutics available for a broader spectrum of applications.