Measuring the long-term safety and efficacy of Covid-19 vaccines

The news that two UK recipients of the Covid-19 Pfizer-BioNTech mRNA vaccine suffered allergic reactions illustrates the need for accurate recording of any adverse events following administration of Covid-19 vaccines. As these vaccines are new, we don’t yet have long-term data on their safety and efficacy. This data is essential to help build public confidence in these vaccines and ensure take-up of the vaccines is high; not just in the UK but globally as well. The data will also help identify how frequently vaccination is needed to ensure vaccine recipients retain their immunity to Covid-19.

The UK is well-placed to collect this data. We have a National Health Service that has developed computerised medical records for use in general practices on a population of around 67 million people. These electronic medical records provide longitudinal data on people’s health and medical experiences. They can now also be linked to other data; such as hospital admissions records and mortality records, as well as to the results of Covid-19 tests, increasing their value for monitoring the safety and efficacy of the new Covid-19 vaccines.

The comprehensive nature of these medical records and the large population they cover mean that they can be used to look at safety and efficacy of Covid-19 vaccines in specific populations. This could be, for example, by age, sex, medical history or ethnic group. It would also be possible to look at more serious health outcomes and death rates by linkage to other data sets. Hence, planning how we would use these data is essential and needs to start now.

The use of these data will be facilitated by the recently developed clinical codes for Covid-19 vaccines for recording information in electronic medical records. These codes include, for example, codes for whether people attended or did not attend for their vaccination appointment; whether they declined to be vaccinated; and whether they had a clinical contra-indication to being vaccinated. Other codes allow recording of the specific vaccine that was administered, which will be essential for comparing the long-term safety and efficacy of different Covid-19 vaccines.

The data from electronic medical records can be supplemented by the reporting of any suspected adverse events by health professionals to the MHRA via the Yellow Card Scheme. Vaccine recipients should also be encouraged to report any reactions directly to the MHRA a well as to their doctor. This allows the MHRA to build up information on the safety profile of the new Covid-19 vaccines and advise patients and the public of any potential problems.