Coronavirus: Herd immunity to COVID-19 a 'dangerous fallacy' with no evidence it'll work - experts

Dozens of experts from around the world have condemned world leaders hoping to fight the coronavirus through building up herd immunity, saying it's "a dangerous fallacy unsupported by the scientific evidence".

Instead, they should look to countries that have shown success at wiping out the virus - such as Vietnam and New Zealand. 

Sweden, the UK and the US have tried - at different times - a strategy of controlling the spread of the virus rather than eliminating it, hoping to build up immunity in less vulnerable populations to protect those more likely to fall seriously ill or die. 

The UK abandoned the plan when it became clear it would result in mass casualties. Sweden has persisted, keeping the spread relatively under control but experiencing higher mortality rates than its neighbours, and is currently under greater restrictions than New Zealand. The US response has been muddled, but the White House this week confirmed it was essentially giving up on lockdowns and embracing the "let people die" strategy, in the words of the Los Angeles Times

Eighty researchers have now penned an open letter for medical journal The Lancet, saying it's impossible to control the spread through younger populations and protect the older and more vulnerable. COVID-19 overwhelmingly kills the elderly, but can also be fatal in younger people and lead to long-term sickness.

"Effective measures that suppress and control transmission need to be implemented widely, and they must be supported by financial and social programmes that encourage community responses and address the inequities that have been amplified by the pandemic," the experts say.

"Continuing restrictions will probably be required in the short term, to reduce transmission and fix ineffective pandemic response systems, in order to prevent future lockdowns. The purpose of these restrictions is to effectively suppress SARS-CoV-2 infections to low levels that allow rapid detection of localised outbreaks and rapid response through efficient and comprehensive find, test, trace, isolate, and support systems so life can return to near-normal without the need for generalised restrictions. 

"Protecting our economies is inextricably tied to controlling COVID-19. We must protect our workforce and avoid long-term uncertainty."

SARS-CoV-2 is the name of the virus which causes COVID-19 and related conditions such as MIS-C and long COVID. 

Oxford University's Government Response Stringency Index
Oxford University's Government Response Stringency Index. Photo credit: Our World in Data

They say the virus' second wave, which has hit Europe particularly hard, has a "renewed interest in so-called natural herd immunity approaches" due to "widespread demoralisation and diminishing trust" caused by rolling lockdowns.

But with reports of secondary infections of COVID-19 resulting in death, there's little other option than to control the spread and wait for a vaccine, they say. 

"There is no evidence for lasting protective immunity to SARS-CoV-2 following natural infection, and the endemic transmission that would be the consequence of waning immunity would present a risk to vulnerable populations for the indefinite future.

"Such a strategy would not end the COVID-19 pandemic but result in recurrent epidemics, as was the case with numerous infectious diseases before the advent of vaccination."

The authors cite New Zealand, Japan and Vietnam as models to follow. According to Oxford University's Government Response Stringency Index, which measures the level of restrictions each country has at present, New Zealanders have more freedoms than those in Sweden, the US and UK. 

"The evidence is very clear: controlling community spread of COVID-19 is the best way to protect our societies and economies until safe and effective vaccines and therapeutics arrive within the coming months," the experts say. "We cannot afford distractions that undermine an effective response; it is essential that we act urgently based on the evidence."

More than 1.1 million people have died as a result of COVID-19 to date, with a case fatality ratio of just under 4 percent. The true numbers of those dead and infected are unknown, but testing suggests it's far more widespread than the confirmed figures show. 

A study this week, also published in The Lancet, found New Zealand led the world with its 'go hard and go early' strategy.