Coalition of scientists call for herd immunity plan - so could it work for the UK?

Thousands of health experts and researchers across the world are backing a campaign for coronavirus lockdown restrictions to be ditched in favour of a herd immunity strategy.

The so-called Great Barrington Declaration - an open letter named after the US town where it was written - has also been signed more than 65,000 citizens of countries all over the globe who want members of less vulnerable demographics to be allowed to return to normal life.

However, a new report published from the UK’s independent Scientific Advisory Group for Emergencies (Sage) warns that herd immunity is “irresponsible and unethical to try”.

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What do the scientists say?

The Great Barrington Declaration has been signed by experts from a number of UK universities, and advocates for letting the virus spread in low-risk groups in the hope of achieving herd immunity.

Sunetra Gupta of Oxford University, Jay Bhattacharya of Stanford University and Martin Kulldorff of Harvard University authored the open letter, which says that lockdown restrictions are having “devastating effects” on physical and mental health.

The scientists write that lockdowns are resulting in“ lower childhood vaccination rates, worsening cardiovascular disease outcomes, fewer cancer screenings and deteriorating mental health - leading to greater excess mortality in years to come, with the working class and younger members of society carrying the heaviest burden”.

The letter calls for a strategy of “focused protection” for people in higher risk groups, but argues that “the most compassionate approach... is to allow those who are at minimal risk of death to live their lives normally to build up immunity to coronavirus through natural infection”.

What do we know about herd immunity?

Scientific consensus on the effectivness of herd immunity has yet to be reached, but almost all experts agree that the strategy is dangerous.

Critics have “warned that the declaration ignores the growing evidence on long Covid – whereby thousands of fit and young people who contract the virus have been left with debilitating symptoms months after a mild infection”, says the London Evening Standard.

And Dr Jeremy Rossman, a senior lecturer in virology at the University of Kent, notes that research suggests protective antibodies may “decay rapidly”, with multiple confirmed cases of reinfection.

Rossman also points out that countries such as Sweden, which decided against locking down during the first wave of coronavirus, “were not able to successfully protect the vulnerable population”.

Gregg Gonsalves, an epidemiologist at Yale University, goes a step further, arguing that herd immunity strategies mean “culling the herd of the sick and disabled”, and describing the defence of such an approach as “grotesque”.

Will it work in the UK?

In early March, World Health Organization (WHO) director-general Dr Tedros Adhanom Ghebreyesus issued a statement warning against herd immunity as a strategy for beating the pandemic.

“Covid-19 is a new virus to which no one has immunity. That means more people are susceptible to infection, and some will suffer severe disease,” Tedros said. “There is currently no evidence that people who have recovered from Covid-19 and have antibodies are protected from a second infection.”

In August, WHO chief scientist Dr Soumya Swaminathan said that at least 70% of the world population would need to be immune “to really break the chain of transmission”.

“If you allow this to happen naturally, it will take a long time, of course, but more importantly, it’s going to do a lot of collateral damage,” Swaminathan explained, adding that “even if 1% of people who get infected are ultimately going to die, then this can add up to a huge number of people, if we look at the global population”.

In the UK, a 1% death rate would equate to around 450,000 lives lost - more than ten times the current tally - while worldwide it would equate to upwards of 54 million deaths.

Tests involving 20,000 people carried out by India’s National Centre for Disease Control (NCDC) in July found that 23.4% of Delhi residents had antibodies to the virus after the pandemic hit the city hard.

And Manaus, a coronavirus outlier located deep in the Amazon rainforest, also saw “excess deaths” - deviations in mortality from the expected level - drop from about 120 per day in May to “practically zero” in August, as The Washington Post reported at the time.

But like Delhi, the Brazilian city also paid the price of achieving something resembling herd immunity, recording a huge number of deaths in the early months of the pandemic, when “burials were running at five times their normal rate”, according to The Times.