Britain Nears Herd Immunity

More than 73 percent of Britons will be vaccinated or previously-infected by Monday.

National News (“UK ‘to hit herd immunity next week’ as vaccines break the link between cases and deaths“):

The UK will reach the threshold of herd immunity against Covid-19 on April 12, according to modelling by University College London, as vaccines “break the link” between cases and deaths.

The Office for National Statistics said the number of weekly coronavirus deaths in England and Wales had fallen by 92 per cent from the peak of the second wave.

While this is fantastic news for them, they very much got here the hard way.

The latest figures covering the week ending March 26 showed 719 deaths in a week, down from 8,945 from a week in January. On January 19 alone – the UK’s deadliest day of the pandemic – 1,358 people died with Covid-19.

Scientists said the proportion of people who have protection against the virus – either through vaccines, previous infection or natural immunity – will hit 73.4 per cent next Monday, the same day non-essential shops and outdoor hospitality reopens.

Prof Karl Friston from UCL told The National that the UK’s current threshold for herd immunity was 72 per cent. “When you add to both the vaccine-induced immunity and natural immunity through previous infection and a small proportion of people who might have pre-existing or innate immunity – which could be up to 10 per cent – you can see immediately there aren’t many people left. “Suffering the Christmas surge and the success of the vaccination campaign has put us in a good position for reaching the threshold of herd immunity.”

A separate study by Imperial College London found infections had fallen by about 60 per cent since February – but the data suggests the decline is levelling off.

So, while vaccinations have helped considerably—as has a shrewd policy decision to prioritize getting one dose into as many people as possible as fast as possible rather than the two doses to become “fully vaccinated”—the fact of the matter is that they’re reaching herd immunity so fast because so many have already been infected.

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James Joyner
About James Joyner
James Joyner is Professor and Department Head of Security Studies at Marine Corps University's Command and Staff College. He's a former Army officer and Desert Storm veteran. Views expressed here are his own. Follow James on Twitter @DrJJoyner.


  1. I don’t want to be a dog in the manger but this seems to be an opportune time to consider that “herd immunity” is a hypothesis rather than a law of physics.

  2. JohnSF says:

    I for one would be a leetttlle cautious about achieving herd immunity based on single dose vaccination, rather than the two doses recommended for the vaccine types we’ve been using.
    Current evidence indicates the single dose certainly reduces average infection severity, and may well reduce replication levels, it might not be sufficient to deal with potential proliferation of new variants with a economic “re-opening” and a partially immunised population.

    We shall see, but sometimes our current government has a “bias to optimism” that can backfire badly.
    Professor Friston’s estimates of prior infection are just estimates AFAIAA; we really don’t have hard numbers on seropositive levels. Which given the money spent on “test and trace” we damn well should have.

  3. steve says:

    Let me second Dave that herd immunity at 73% is just an educated guess. It is a new virus.


  4. de stijl says:


    A mutating novel virus. With a shit ton of hosts.

    Where immunity to v1 may not grant you full immunity to the new and improved v2.

    This a layperson’s take, but I bet C19 variants will be bopping about years from now and we will need yearly booster jabs.

    Viruses have no brains, but they are very adaptive by force of sheer numbers.

  5. Hal_10000 says:

    the fact of the matter is that they’re reaching herd immunity so fast because so many have already been infected

    The UK’s deaths per million is at 1863. That’s a bit higher than the US Spain or Portugal, a bit lower than Italy, Slovakia or Belgium. None of those countries are near herd immunity. About a third of it is infection and two-thirds are vaccinations.