The need for active surveillance of the safety and effectiveness of COVID-19 vaccines

14 May 2020

(First published as a BMJ Rapid Response on 12th May 2020)

A key component of efforts to control COVID-19 will be an effective vaccine. There are many potential COVID-19 vaccines in preclinical development and clinical trials around the world.

History has shown that the benefits far outweigh risks for vaccines of infectious diseases. The normal vaccine development process including clinical trials may take 10 – 15 years. To address urgent public health need, such as the COVID-19 pandemic, the vaccine development process can be dramatically shortened to as little as 12-18 months, including testing and release. To protect populations urgently, the release of a COVID-19 vaccine will be based on limited pre-marketing clinical data. Therefore, post-marketing observational studies will be vital to better understand effectiveness and safety.

Whilst pre-marketing activities provide important information on vaccine safety and efficacy, post-marketing data is essential to provide real-world evidence on the use, effectiveness and safety of the vaccine in larger groups of people. For public health, effectiveness (protecting vaccinees from the disease in real-world conditions) is more important than vaccine efficacy tested in clinical trials (comparing vaccinated with non-vaccinated individuals). Effectiveness depends not only on vaccine potency but also performance of vaccination programmes and other factors which may influence the disease risk itself, such as seasonality. Given the limited pre-authorisation data, it is also crucial to obtain near real-time notification of the effectiveness and potential safety signals of the vaccine when used routinely in the population.

For COVID-19, vaccination coverage is expected to be high, so the standard method of comparing disease incidence between vaccinated and unvaccinated groups may not be suitable due to the lack of an unvaccinated comparator group and ethical considerations.

Examples of real-world vaccine studies in the UK include active surveillance on the 2009 H1N1 (swine flu) vaccine1 and since 2014, annual active or passive enhanced safety surveillance on seasonal flu vaccines2, conducted in collaboration with National Institute for Health Research (NIHR) Clinical Research Networks (CRNs), GP practices or other sites where the vaccine is administered. These surveillance methods benefit from the structure of the NHS and were developed to allow near real-time reporting of safety and effectiveness signals, which will be crucial for monitoring COVID-19 vaccines.


  1. Mackenzie IS, MacDonald TM, Shakir S, Dryburgh M, Mantay BJ, McDonnell P, Layton D. 2012. Influenza H1N1 (swine flu) vaccination: a safety surveillance feasibility study using self-reporting of serious adverse events and pregnancy outcomes. Br J Clin Pharmacol. 73(5):801-11.
  2. McNaughton R, Lynn E, Osborne V, Coughtrie A, Layton D, Shakir S. 2016. Safety of Intranasal Quadrivalent Live Attenuated Influenza Vaccine (QLAIV) in Children and Adolescents: A Pilot Prospective Cohort Study in England. Drug Safety. 39 (4): 323-333

BMJ Rapid Response Re: Exit strategy to control covid-19 and relaunch the economy. Cam Bowie and Tony Hill; 369 doi: https://doi.org/10.1136/bmj.m1851