New Delhi: A day after Goa's Health Minister Vishwajit Rane recommended ivermectin to all above 18 to combat Covid in the state, the World Health Organisation on Tuesday has warned against its use.

"Safety and efficacy are important when using any drug for a new indication. @WHO recommends against the use of ivermectin for #COVID19 except within clinical trials," Soumya Swaminathan, the global health body's chief scientist, said in a tweet.

The Goa state government on Monday cleared a new Covid treatment protocol which recommends all residents above the age of 18 to take five tablets of the ivermectin drug, in order to prevent the steep and sometimes fatal viral fever, which accompanies a Covid-19 infection.

Rane, while speaking to reporters, said that the ivermectin drug would be made available at all health centres in the state and should be taken by all residents, irrespective of whether they have Covid-19 symptoms or otherwise.

Last week, a peer-reviewed research had claimed that global ivermectin use can end Covid-19 pandemic, as the medicine significantly reduces the risk of contracting the deadly respiratory disease when used regularly.

The peer review, which included three US government senior scientists and was published in the American Journal of Therapeutics, touted the common anti-parasitic ivermectin as a miracle cure for Covid-19 by doctors and campaigners the world over.

In her tweet, Swaminathan also attached a warning issued by the German health care and life sciences giant Merck.

"Scientists continue to carefully examine the findings of all available and emerging studies of ivermectin for the treatment of Covid-19," read the statement from Merck.

"...to-date, our analysis has identified: No scientific basis for a potential therapeutic effect against Covid-19 from pre-clinical studies; No meaningful evidence for clinical activity or clinical efficacy in patients with Covid-19 disease, and; A concerning lack of safety data in the majority of studies," the statement added.

The WHO had, in March, issued a similar warning against the use of ivermectin in treating Covid patients.

The global health agency said that there was a "very low certainty of evidence" on ivermectin's effects on mortality, hospital admission and getting rid of the virus from the body.

Rane also stated that expert panels from the UK, Italy, Spain and Japan, found a large, statistically significant reduction in mortality, time to recovery and viral clearance in Covid-19 patients treated with ivermectin.

The US Food and Drug Administration (FDA) had also, in April last year, recommended against the use of ivermectin in treating Covid patients. Besides, the Union ministry of health and family welfare had also reportedly opted out from including Ivermectin in its official Clinical Management Protocol for Covid-19 last year.