A new protein-based vaccine may help bring COVID-19 vaccination access to the world’s less wealthy nations. The new vaccine has been shown in animal trials to stimulate a strong immune response and protect against viral infection.
While the speed at which safe and effective vaccines against COVID-19 have been developed, tested and rolled out across many countries is a significant achievement, many people around the world still don’t have access to COVID vaccines.
Vaccine equity remains a key challenge in ending the COVID-19 pandemic. Just as the most vulnerable community members often lack vaccine access within countries, wealthy nations around the world tend to be the most highly vaccinated.
Researchers at the Massachussetts Institute of Technology (MIT) and Beth Israel Deaconess Medical Center in the US have developed a new protein subunit vaccine against COVID that they hope will help to close this vaccine equity gap.
It contains fragments of the SARS-CoV-2 spike protein found on the virus’ surface – the same protein targeted by most existing vaccines.
The spike protein subunits are arranged on a ‘virus-like particle’ made up of surface antigens from another virus, hepatitis B. Adding the hepatitis B antigen makes the vaccine more immunogenic, meaning that it produces a stronger immune response.
“Protein-based subunit vaccines are a low-cost, well-established technology that can provide a consistent supply and is accepted in many parts of the world,” says J Christopher Love, a professor of chemical engineering at MIT and one of the study’s senior authors.
The research team, which began work on the COVID vaccine in early 2020, had set out to optimise both ease of vaccine production and protection against disease.
Their vaccine can be produced using yeast cells, which are easier to grow and work with than cultured mammalian cells typically used to produce protein subunit vaccines. The yeast can manufacture both the SARS-CoV-2 spike protein fragment and the hepatitis B particle.
“One of the key things that separates our vaccine from other vaccines is that the facilities to manufacture vaccines in these yeast organisms already exist in parts of the world where the vaccines are still most needed today,” explains Neil Dalvie, a graduate student at MIT who was one of the paper’s lead authors.
If it proves to be safe and effective in humans as well, the vaccine should be relatively cheap and easy to produce. It can also be stored in an ordinary fridge, compared to mRNA vaccines which require ultra-low storage temperatures. Both features should go some way to making COVID vaccination more accessible to countries that currently lack access.
Another advantage of the vaccine design is that it’s easy to incorporate spike protein mutations or new antigens to the virus-like particle. That means the researchers’ vaccine framework could be useful in efficiently creating vaccines targeted to new strains or viruses.
The team has already updated their vaccine candidates to include mutations found in the Delta and Lambda variants of SARS-CoV-2, for example.
“We could make mutations that were seen in some of the new variants, add them to the RBD but keep the whole framework the same, and make new vaccine candidates,” says Sergio Rodriguez-Aponte, another lead author and also an MIT graduate student.
“That shows the modularity of the process and how efficiently you can edit and make new candidates.”
“In principle, this modularity does allow for consideration of adapting to new variants or providing a more pan-coronavirus protective booster,” adds Love.
The vaccine is currently being manufactured at scale by the Serum Institute of India and is in human clinical trials.