People enjoy beers and food at an outdoor restaurant where waitstaff wear yellow shirts.

Public health experts warn against herd immunity strategy to manage COVID-19

As herd immunity gains new ground as a possible public health strategy, a growing chorus of public health experts is speaking out against it as an extremely dangerous idea.

The World

In early October, three scientists met in Great Barrington, Massachusetts, to discuss the idea of achieving natural herd immunity as a public health strategy.  

At the headquarters of the American Institute for Economic Research, a libertarian think tank, Martin Kulldorff, a biostatistician from Harvard Medical School, Sunetra Gupta, an epidemiologist from Oxford University in the United Kingdom, and Dr. Jay Bhattacharya, a health economist from Stanford University, launched The Great Barrington Declaration, asking global policymakers to take the controversial so-called herd-immunity approach to the pandemic — to just let the virus spread. 

Related: Israelis protest against new COVID-19 measures that restrict protests

Kulldorf reasoned: “For the short term, my major concern of the pandemic is all the collateral damage,” referring to the pandemic’s interruptions of daily life. Gupta agreed. All three scientists signed the declaration on video and clinked champagne glasses. 

As the United States and Europe brace for new outbreaks of the coronavirus and with that, more restrictions, a growing chorus of public health experts worldwide is speaking out, warning that the idea is extremelydangerous. 

Related: Qingdao tests all 9 million residents for COVID-19 

This proposal, which has been circulating among various scientific communities, advocates for the end of pandemic restrictions or crowd limits, and calls for the reopening of all businesses and restaurants — regardless of rising infections. 

“I think [the herd immunity proposal] is truly, incredibly problematic."

William Hanage, public health researcher, Center for Communicable Disease Dynamics, Harvard University

“I think it’s truly, incredibly problematic,” said William Hanage, a public health researcher at Harvard’s Center for Communicable Disease Dynamics, who has been leading pushback on the idea. 

Yet, proponents assert that if higher-risk people are protected and lower-risk people get infected, recover, and, in theory, develop natural immunity, then the virus won’t be able to spread much in the future. Kulldorff told The World that the current approach — restrictions, lockdowns, and curfews — put too many lives on hold, worsening too many other problems.

“Children should be able to go to schools and young adults have very low risk, so we should let them live their lives normally."

Martin Kulldorff, biostatistician, Harvard Medical School, Harvard University

“Children should be able to go to schools and young adults have very low risk, so we should let them live their lives normally,” Kulldorff said. 

Related: South Korea bans seating at big cafés to prevent COVID-19 outbreak

Higher-risk groups, such as older people and those with chronic health conditions, will just have to get better protection, Kulldorf said. 

Herd immunity banks on the concept that when enough people are immune to a disease, new infections can’t spread and new outbreaks can’t take hold. It may seem alluring, months into a pandemic that has turned the world upside down, to take such an approach. But Hanage said the declaration relies on a fiction that presumes it’s possible to separate out and protect older, at-risk networks of people from the rest of the population. 

Hanage likens the approach to “a wildfire sweeping down a valley.” It’s simply not sustainable to let the fire burn in the valley while standing inside a house full of antiques with a bucket of water, “splashing any sparks that try to get in.” 

Many global health leaders agree. Dr. Tedros Adhanom Ghebreyesus, director of the World Health Organization, called the herd-immunity strategy unethical

“Never in the history of public health has herd immunity been used as a strategy responding to an outbreak — let alone a pandemic."

Dr. Tedros Adhanom Ghebreyesus, director, World Health Organization

Herd immunity is achieved by protecting people from a virus, not by exposing them to it,” Dr. Tedros said during a press briefing last week

Upward of 90% of the world population is still susceptible to COVID-19. The way to protect people, he said, is with effective vaccinations, not naturally exposing them to diseases. 

“Never in the history of public health has herd immunity been used as a strategy responding to an outbreak — let alone a pandemic,” he continued.

In the US, the nation’s top infectious disease doctor, Dr. Anthony Fauci, has said that letting the virus spread unchecked would bring an enormous death toll. His boss, the head of the National Institutes of Health, Dr. Francis Collins, recently described this idea in a news interview as “fringe” and “dangerous.”

Related: Fauci shuns politicization of COVID-19 science

But The Great Barrington Declaration has gained more fuel since it was introduced. Thousands of scientists worldwide have signed on, and it’s not just scientists on board. Kulldorff and his colleagues recently met with US Health and Human Services Secretary Alex Azar. 

Kulldorff said the discussion was good. “Secretary Azar asked a number of questions.”

Azar said their proposal reinforces President Trump’s coronavirus strategy. 

In response to the mounting attention, dozens of health researchers from around the globe published what they’ve called the John Snow Memorandum last Thursday in the medical journal The Lancet

The document is named after John Snow, a 19th-century English doctor who famously identified the source of a deadly cholera outbreak in London, when he traced it back to a water pump. His realization helped transform water systems and public health worldwide.

“For me, the big connection is the importance of using what we know about epidemiology and what we’ve learned about disease spread to make sure we take the most appropriate actions in the current pandemic."

Emma Hodcroft, epidemiologist, University of Basel

“For me, the big connection is the importance of using what we know about epidemiology and what we’ve learned about disease spread to make sure we take the most appropriate actions in the current pandemic,” said Emma Hodcroft, a coauthor and epidemiologist at the University of Basel. 

Hodcroft said there are too many unknowns about this new coronavirus virus, SARS-COV-2, to just let it spread. For example, how long does immunity last from a natural infection? 

And certainly, when it comes to seasonal coronaviruses that have been circulating in humans for many years, you can catch these many times in your life and you do. It’s probable that later infections might not be as severe, but we don’t know this information about SARS-COV-2, so it’s really risky to decide that that’s our strategy when we don’t even know if that will work,” Hodcroft said.  

It’s also unclear how COVID-19 impacts young people. Already, serious complications and deaths have been documented. 

Early on in the pandemic, the idea of herd immunity came up in Europe. Sweden, for example, never went into full lockdown. The proposal faced a major backlash in the UK, and leaders dropped it as the outbreak surged out of control. 

Related: Sweden and Denmark have taken two very different approaches to COVID-19. What's working?

Months later, as this idea gains new ground, Hodcroft said there’s a false dichotomy presented to end the pandemic: full lockdowns or no restrictions at all.

Instead, Hodcroft believes that with measured approaches and an effective vaccine that provides long-term immunity, everyone can truly get protected from the coronavirus. 

I do think it’s a kind of middle ground that shows you don’t have to lock everyone away in order to eventually get the virus under control,” she said. “With more targeted restrictions, with more clarity on virus spreads and with really effective test and trace teams, we can reopen society to a large degree and keep the number of cases low.” 

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