1.3 COVID-19 vaccines
By December of 2020, more than 200 vaccine candidates for COVID-19 were under development, with more than 50 being taken forward into trials on humans. A variety of approaches were made (Table 2).
| Vaccine type | Manufacturer (name) |
|---|---|
| mRNA for spike protein | Pfizer/ BioNTech Moderna CureVac |
| Vector with gene for spike protein | Oxford/Astra Zeneca (Sputnik V) Johnson & Johnson /Janssen CanSinoBio (Convidecia) |
| Spike protein | Novavax/ GSK |
| Inactivated virus | Valneva Sinovac (CoronaVac) Sinopharm (BB1BP CorV) |
Interestingly, it was the newest methods – vector vaccines, and mRNA vaccines, which came through first. One strategy for COVID-19 is to take the gene that encodes the spike protein and insert it into a harmless virus vector. The vector has very limited capacity to replicate, but it still produces the COVID-19 spike-protein which induces specific antibody production. This approach has been used by the Oxford/Astra-Zeneca and Russian Sputnik V vaccines.
mRNA vaccines rely on the recipient’s cells taking up the gene and expressing it, so that virus antigens (but not virus) are produced by the cells of the body. This approach is relatively new and it was used by the Pfizer/Biontech and Moderna vaccines against COVID-19. This method has been so successful that it has revolutionised vaccine production, and is now being applied to other infectious diseases and cancer therapy.