[16] The American Public Health Association and 13 other public-health groups in the United States warned in a joint open letter that the "Great Barrington Declaration is not grounded in science and is dangerous".

[13] The Great Barrington Declaration received support from some scientists, the Donald Trump administration, British Conservative politicians, and from The Wall Street Journal's editorial board.

[22] Gupta has been a critic of early COVID-19 lockdown strategy, arguing that the cost is too high for the poorest in society, and expressing concern about the risk of widespread starvation in many countries because of lockdown-related disruptions in food supply chains.

", in which he claimed that there was little evidence to support shelter-in-place orders and quarantines of the COVID-19 pandemic in the United States,[27] and was a lead author of a serology study released in April which suggested that as many as 80,000 residents of Santa Clara County, California might have already been infected with COVID-19.

[38] The declaration was sponsored by the American Institute for Economic Research (AIER), a libertarian free-market think tank based in Great Barrington, Massachusetts,[39][40] which has a history of promoting climate change denial,[41][42][43] and the benefits of sweatshops.

[44][45] Byline Times journalist Nafeez Ahmed has described the AIER as an "institution embedded in a Koch-funded network that denies climate science while investing in polluting fossil fuel industries".

[48][49][50] More than 100 psychotherapists, numerous homeopaths, physiotherapists, massage therapists, and other non-relevant people were found to be signatories, including a performer of Khoomei—a Mongolian style of overtone singing—described as a "therapeutic sound practitioner".

[50] Tedros Adhanom Ghebreyesus, the Director-General of the World Health Organization, warned against the idea of letting the virus spread in order to achieve herd immunity at a 12 October 2020 press briefing, calling the notion "unethical".

[54] British Secretary of State for Health and Social Care Matt Hancock said in the House of Commons on 13 October that the Great Barrington Declaration's two central claims – that widespread infection would lead to herd immunity and that it would be possible to segregate the old and vulnerable – were both "emphatically false".

"[62] The Infectious Diseases Society of America, representing over 12,000 doctors and scientists, released a statement calling the Great Barrington Declaration's proposals "inappropriate, irresponsible and ill-informed".

"[13] Europe's largest association of virologists, the Gesellschaft für Virologie, released a statement co-authored by Christian Drosten saying the declaration's proposals were liable to result in "a humanitarian and economic catastrophe".

[33][66] The Wall Street Journal's editorial board accused Collins of "work[ing] with the media to trash the Great Barrington Declaration" and of "Shut[ting] down covid debate".

"[16] David Naylor, co-chair of the Government of Canada's COVID-19 Immunity Task Force, told the National Post: "Obviously, the Great Barrington fix will excite the minimizers who pretend COVID-19 is not much worse than the flu and enliven the libertarians who object to public health measures on principle ...

[10][67] According to Naylor, the policy advocated by signatories of the declaration would never be the "controlled demographic burn that some zealots imagine", and because of exponential growth of infections would lead to a situation where "with masses of people sick in their 40s and 50s; hospitals will be over-run and deaths will skyrocket as they did in Italy and New York".

[10] With the prospect of a vaccine available within months, Naylor questioned the logic of the Great Barrington strategy, asking: "Why on earth should we rush to embrace a reckless prescription for a demographically-selective national 'chickenpox party' involving a dangerous pathogen?".

[69] David Nabarro, a special envoy of the World Health Organization, said governments should refrain from using "lockdowns as the primary method to control the virus", a comment cited with approval by the American president, Donald Trump.

[70] However, Nabarro rejected Trump's interpretation of his comments, saying that the lockdowns in the spring had been necessary as emergency measures, to buy time, and emphasized the need to find a "middle way", with "masks, social distancing, fewer crowds, testing and tracing" the right way forward.

[54] Of the declarations' signatories he said: "There's a lot of other people who have also signed it and guess what, it's the usual suspects … It's Karol Sikora who knows nothing about this whatsoever but who is endlessly self-promoting, and you've got Michael Levitt who's got a bad case of Nobel Prize disease.

[73] Michael Head, senior research fellow in global health at University of Southampton, said the declaration was "a very bad idea" and doubted if vulnerable people could avoid the virus if it were allowed to spread.

"[74] Michael Osterholm, an American epidemiologist, regents professor, and director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said that the Great Barrington Declaration was "a dangerous mix of pixie dust and pseudoscience.

"[76] John M. Barry, a professor at the Tulane School of Public Health and Tropical Medicine and author of a book on the 1918 flu pandemic, wrote in The New York Times that the Great Barrington Declaration sounds attractive until one examines "three enormously important omissions".

[77] Barry said that while it was too late for the United States to achieve "near containment of the virus", as South Korea, Australia and Japan had done, the US could still aim for results comparable to those of Canada or Germany, where daily deaths were a couple of dozen at the time of writing (October 2020).

[78] The American Institute for Economic Research (AIER), at whose meeting the declaration was launched, has been described as a libertarian think tank that has received funding from the Koch Foundation and engages in climate change denial.

[84] David Livermore, professor of medical microbiology at the University of East Anglia explained his decision to sign the declaration, saying that "never in history have we handled a pandemic like this" and that "future generations will look back aghast".

Anthony Brooks, professor of genetics at the University of Leicester, criticized the British Government Chief Scientific Adviser, Patrick Vallance, alleging that "Being a senior vice president at a drug company doesn't give you the same background that others have.

[25] The Trump administration was reported to support the Great Barrington Declaration, based on statements made to Newsweek and other publications by senior advisers that were not authorized to speak on the record.

[89][90][91] Conservative MP for New Forest West, Desmond Swayne asked the Leader of the House of Commons if a debate could be held on what he called "censorship" and "the sinister disappearance of the link from Google to the Great Barrington declaration".

[20][103] Taking its name from John Snow, the epidemiologist who worked on the 1854 Broad Street cholera outbreak,[20][101] it states that the herd immunity idea is "a dangerous fallacy unsupported by the scientific evidence".

[16] It acknowledges that COVID-19 restrictions have led to demoralization, making such an idea attractive, but states that "there is no evidence for lasting protective immunity to SARS-CoV-2", adding that "such a strategy would not lead to the end of COVID-19, but instead result in recurrent epidemics, as was the case with numerous infectious diseases before the advent of vaccination.

"[16] The letter's authors were co-ordinated by Deepti Gurdasani, clinical epidemiologist at Queen Mary University of London,[104][105] and included researchers and clinicians such as Marc Lipsitch, William Hanage,[106][16] Nahid Bhadelia,[16] Isabella Eckerle,[107] Emma Hodcroft,[107] Florian Krammer,[108] Martin McKee,[109] Dominic Pimenta,[110] Viola Priesemann,[105] Devi Sridhar,[111] Gavin Yamey,[112] and Rochelle Walensky.