Protein subunit vaccines: what are they, and how do they work?

The drug company Novavax recently announced the results of their new vaccine, which is known as a protein subunit vaccine and, incredibly, uses technology based on insect cells, as Eva Higginbotham explains...

Eva - One of the most tried and tested forms of vaccination is called a protein subunit vaccine. This is where large amounts of one part of a virus are produced in culture in the laboratory, purified and then injected into the body. The hepatitis B and the cervical cancer vaccines are made this way. And recently the company Novavax announced they’ve developed a method to do this for the new coronavirus. They add the gene for the coronavirus spike protein to insect cells grown in the laboratory dish. The cells churn out large amounts of coronavirus spike proteins, which clump together and can be easily separated and purified into a vaccine. When they’re injected, cells nearby pick up these proteins and present them to the immune system, producing protective antibodies within a few weeks. This is a very safe technique that is also easy to scale up and the resulting vaccine is easy to transport and store. But one downside is that it does tend to produce mostly antibodies rather than white blood cells, which might make the protective more short-lived and potentially less effective against variants of the virus.