Smokers are more vulnerable to COVID-19 than non-smokers, according to the World Health Organization (WHO) on Monday.

A review of studies by public health experts convened by the WHO found that smokers are at a higher risk of contracting fatal diseases.

“COVID-19 is an infectious disease that primarily attacks the lungs,” the WHO said in a written statement.

“Smoking impairs lung function making it harder for the body to fight off coronaviruses and other diseases,” it added.

The WHO also warned researchers, scientists and the media about amplifying claims that tobacco or nicotine could reduce the risk of COVID-19.

The statement came after several studies showing that the number of non-smokers was higher among COVID-19 patients compared to smokers.

A study by French scientists on the science portal Qeios late April suggested that smoking can be a protective factor against the new coronavirus.

The researchers said only 5% of 482 COVID-19 patients at the Pitie-Salpetriere hospital in Paris on Feb. 28-April 9 were smokers.

An earlier study published late March in the New England Journal of Medicine also showed only 12.6% of some 1,099 people infected with the virus were smokers, while the smoking rate in China is around 28%.

According to the WHO, tobacco kills more than 8 million people globally every year.

More than 7 million of these deaths are from direct tobacco use and around 1.2 million are due to non-smokers being exposed to second-hand smoking.

After originating in China last December, COVID-19 has spread to at least 187 countries and regions. Europe and the US are currently the worst-hit regions.

The pandemic has killed nearly 292,000 people worldwide, with total infections more than 4.26 million, while recoveries surpassed 1.49 million, according to figures compiled by the US’ Johns Hopkins University.