Intended for healthcare professionals

Editor's Choice

Covid-19: The fatal attraction of herd immunity

BMJ 2020; 370 doi: (Published 24 September 2020) Cite this as: BMJ 2020;370:m3714

Read our latest coverage of the coronavirus outbreak

  1. Kamran Abbasi, executive editor
  1. The BMJ
  1. kabbasi{at} Follow Kamran on Twitter @KamranAbbasi

Scientists are in dispute.1 There is nothing new in this. Debate is to be encouraged—truth is nuanced2—except that the debate comes at a critical moment in the response to covid-19.3 It is a debate being played out in most countries and is simply this: what is the best strategy for the second surge in covid-19 infections?

We are still learning about covid-19. Fear was a factor in the initial response, and patients might have been better served by “ordinary decision making in extraordinary times.”4 In the meantime, the evidence base for treatments, such as convalescent plasma and remdesivir, continues to grow.56 Management approaches in pregnancy, for example, are better informed.78

Clinicians are establishing new normals in primary care and for treating complex illnesses such as multiple sclerosis.910 Universities and medical schools are struggling with the financial effects of covid-19.11 The business as usual of workforce planning, coping with emergency unit referrals, and drug side effects remains challenging enough.121314

The hope is that the second innings of covid-19 will be less deadly, but that hope is undermined in the UK by a failed test and trace programme.15 Experience from Asia is that effective testing and contact tracing, combined with physical distancing measures, keep an economy open. Health is the key to wealth.

But England’s test and trace regime is a mess; plans to reopen schools, universities, and workplaces are an orchestrated chaos. The consequent rise in new infections has breached testing capacities at commercial testing facilities.1617 It is this central and ongoing failure, combined with the government’s mixed messaging, that raises the spectre of another lockdown or “circuit break.”18 Wealth, it turns out, is hard to achieve without health.

Reasonable questions are being asked about the health and economic impacts of any form of second lockdown. But what is the alternative in the absence of an effective test and trace system? A strategy that tolerates a build-up of herd or population immunity is speculative, bound to overwhelm health services, likely to impact on long term health, and potentially deadly.19

Sweden, the poster child of herd immunity, may eventually tell a different story. T cell immunity may prove to be key to limiting illness and death from covid-19.20 But it is too early to reach those conclusions on the basis of science, however intellectually seductive. The sensible alternative is caution, the precautionary principle. It is a message that chief scientists and medical advisers are now rightly delivering to politicians.

Anthony Fauci, the US government’s lead adviser on infectious diseases, has an impressive track record in speaking truth to power, as he explains in a wide ranging interview.21 What Fauci learnt is that political leaders have respect for you if you base your advice on science and don’t shy away from telling them what they don’t want to hear: “Whether they act on the things you tell them,” says Fauci, “is beyond my power.”

This article is made freely available for use in accordance with BMJ's website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may use, download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trade marks are retained.


View Abstract