COVID-19 is an infectious disease, caused by a coronavirus that was first detected in China at the end of 2019. Vaccines to protect people against this new disease first became available in early December 2020. The majority of people in the UK are now vaccinated. A high proportion will also have developed additional immunity through having COVID-19 disease. The strong immunity among the UK population means that the severe form of COVID-19 disease that was seen in the first 18 months of the pandemic is now very rare in the UK. This is why there is now a more targeted approach to vaccination that aims to protect those who have underlying health conditions or frailty. This puts them at high risk of getting seriously ill, or dying, when they develop a viral infection like COVID-19. Globally, a number of different vaccines for COVID-19 have been trialled, shown to be safe and effective, and approved by regulators. These are monitored on an on-going basis. In the UK, the Medicines and Healthcare products Regulatory Agency (MRHA) has approved six vaccines, although these are not all in use currently. All of the vaccines have been shown to be highly effective against severe COVID-19 but the emergence of new variants has meant that the original vaccines are less effective in preventing milder infections caused by these new variants. Booster doses do provide some temporary protection against the new variants. But the higher levels of immunity provided by boosters are not sustained for long periods. Some vaccines have been developed that target more than one of the new variants. However, they have not added much benefit because of the length of time it takes to develop the new vaccines means that the latest wave of a new variant has passed before they can be rolled-out. The names of the six approved vaccines are:
The Pfizer/BioNTech and AstraZeneca/Oxford vaccines were the most widely used vaccines to protect the UK population in 2021. Since then most booster doses have been the Pfizer/BioNTech and Moderna vaccines. The AstraZeneca/Oxford, Johnson & Johnson and Valneva vaccines are not currently used. Novavax’s vaccine is only given to the small number of people who cannot have the Pfizer/BioNTech and Moderna vaccines. In total, the World Health Organization (WHO) has approved nine different COVID-19 vaccines for use in a public health emergency. This includes the six approved in the UK, along with three more produced by companies in China and India. These met WHO regulatory standards before being added to their emergency list. There are currently around 380 different vaccines at some stage of the research, development, and testing process. While the existing vaccines protect people against getting seriously ill, they do not reduce the transmission of emerging new variants virus. And with the virus still circulating, there is an ongoing risk of new variants emerging for which existing vaccines will only provide limited protection against infection. However, it is highly unlikely that the wall of immunity across the population against severe disease will get significantly less. |