Intended for healthcare professionals

Letters How long does covid-19 immunity last?

Longitudinal data on covid-19 immunity could be collected from medical records

BMJ 2021; 374 doi: (Published 11 August 2021) Cite this as: BMJ 2021;374:n1976
  1. Azeem Majeed, professor of primary care and public health
  1. Department of Primary Care and Public Health, Imperial College London, London, UK
  1. a.majeed{at}

Baraniuk reviews what we know about natural and vaccine induced immunity to SARS-CoV-2.1 Vaccines for covid-19 were eagerly awaited, and their rapid development, testing, approval, and implementation are a tremendous achievement by scientists, drug companies, drugs regulators, politicians, and healthcare professionals and by the patients who have received them.2 Early real world data from vaccine recipients in England, Scotland, and Israel show that vaccination provides a high level of protection from symptomatic covid-19 infection and serious illness, along with a large reduction in the risk of hospital admission and death.

But, because these vaccines are new, we do not yet have information on how long the immunity they generate will last or on how well they will protect against new variants of SARS-CoV-2. Longitudinal data on ”vaccine failures” or re-infections can help guide national policies on how frequently booster doses of vaccines are needed to maintain a good level of immunity in the population, and on whether vaccines need modification to provide protection against new variants of SARS-CoV-2.3

The UK is well placed to collect these data and to secure timely evaluation and integration with information provided by its strong life sciences research industry, to guide public health decision making. We also have an NHS 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 and can be used to estimate the longer term efficacy of covid-19 vaccines.4 This will provide a valuable resource, not just for guiding public health policy in the UK, but for global health.


  • Competing interests: None declared.

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