It was signed by many doctors and scientists and now has 939,000 signatures.

The Declaration was created by:

Martin Kulldorff, professor of medicine at Harvard University, a biostatistician, and epidemiologist with expertise in detecting and monitoring infectious disease outbreaks and vaccine safety evaluations
Sunetra Gupta, professor at Oxford University, an epidemiologist with expertise in immunology, vaccine development, and mathematical modeling of infectious diseases.
Jay Bhattacharya, professor at Stanford University Medical School, a physician, epidemiologist, health economist, and public health policy expert focusing on infectious diseases and vulnerable populations.
Fauci Colluded To Censor The Great Barrington Declaration

Dr. Francis Collins was then the Director of National Institutes of Health (NIH). Dr. Anthony Fauci was then the Director of National Institute of Allergy and Infectious Diseases (NIAID). Dr. Collins didn't invite these esteemed scientists to meet with him to discuss their Declaration which was quickly gaining global support. Collins saw these doctors as "fringe" although they are professors at Harvard, Oxford, and Standford.  So, instead, Collins emailed Fauci on October 8 to tell him to create a quick and devastating takedown of the Declaration!

'There needs to be a quick and devastating take down': Emails show how Fauci and head of NIH worked to discredit three experts who penned the Great Barrington Declaration which called for an end to lockdowns.

The emails show Fauci and NIH Director Francis Collins attempting to coordinate a 'devastating takedown' of the Great Barrington Declaration (GBD)
AIER, a libertarian think tank, sponsored the GBD, which largely abandons lockdowns in favor of herd immunity strategy that allows life to return to normal 
In an October 8 email from Collins to Fauci, the head of the NIH calls the GBD the work of 'three fringe epidemiologists' that 'seems to be getting a lot of attention' 
Collins adds that 'there needs to be a quick and devastating published takedown of its premises.
I don't see anything like that online yet – is it underway?'
Fauci later sends Collins multiple op-eds trashing the GBD in Wired and The Nation Magazine
Jay Bhattacharya — one of the authors and a DailyMail.com contributor — tweeted that he was the subject of a propaganda attack by his own government