Mehra said in a statement these drugs should not be used as treatments for COVID-19 outside of clinical trials.
Treatment with the medications among patients with Covid-19, either alone or in combination with antibiotics, was linked to an increased risk of serious heart rhythm complications and death.
The FDA has already urged against the use of the drug in treating COVID-19 outside of a hospital setting.
Prof Martin Llewelyn from Brighton and Sussex Medical School-who is also leading the study-said, "A widely available, safe and effective vaccine may be a long way off".
"Randomized clinical trials will be required before any conclusion can be reached regarding benefit or harm of these agents in COVID-19 patients", the paper said.
The observed patients, hospitalised between 20 December 2019 and 14 April 2020, were recruited from 671 hospitals in six continents and divided into five groups: those who did not receive any treatment by these drugs (control group), those who were treated with hydroxychloroquine and chloroquine alone, and those who received any of these drugs in combination with macrolide (antibiotic).
Trump said Wednesday that he will finish taking hydroxychloroquine this week, and has not reported any health issues. "Based upon these findings and others, no one should take hydroxychloroquine with or without an antibiotic unless they are in a randomized controlled trial".
Prime Minister Boris Johnson said 181 health workers and 131 care workers have died from the COVID-19 in the country.
He said: "'If drugs as well tolerated as chloroquine and hydroxychloroquine could reduce the chances of catching COVID-19 this would be incredibly valuable".
They explained chloroquine, an antimalarial drug and its analogue, hydroxychloroquine, are commonly used to treat autoimmune diseases including lupus and arthritis.
The death rate among all groups taking the drugs was higher than among people who were not given them.
Those who were treated with hydroxychloroquine had a mortality rate of 18 percent.
The aim of the study is to see whether the anti-malaria drugs can help prevent the disease in uninfected persons.
Those given chloroquine had a 37 percent increased risk of death and a 256 percent increased risk of serious heart arrhythmias.
"Not only is there no benefit, but we saw a very consistent signal of harm", said one study leader, Dr. Mandeep Mehra, a heart specialist at Brigham and Women's Hospital in Boston.
His study looked at almost 15,000 people with COVID-19 getting one of the malaria drugs with or without one of the suggested antibiotics and more than 81,000 patients getting none of those medications.
The results suggest these drugs are "not useful and may be harmful" in people hospitalized with COVID-19, professor Christian Funck-Brentano, of the Sorbonne University in Paris, wrote in a commentary published by the journal.
They said this is due to the design of observational studies, and warned that randomised trials are urgently needed to validate the findings.