Empirical evidence would suggest smokers are "at risk of a negative outcome" with Covid-19, but a study in which smokers are exposed to the virus to prove this point cannot be done as it would be unethical, the acting director-general of the Department of Health, Anban Pillay, told the health committees of both Houses of Parliament on Thursday.

This after Freedom Front Plus MP Philip van Staden said he had quit smoking during the lockdown because he "won't buy smokes on the black market".

After an enquiry from committee chairperson Sibongiseni Dhlomo - who is a medical doctor and former health MEC - Van Staden confirmed he had quit completely, saying he was doing quite well.

He asked how many people being treated in hospitals for Covid-19 were smokers, and how many who died of the virus had smoked.

Pillay said a comparative study would have to be done to determine how many smokers were in intensive care units.

He added empirical evidence "would suggest smokers are at risk of a negative outcome" because smoking damaged the lungs' ability to fight viruses.

"Other viruses cause smokers much harm. We don't anticipate this virus to be any different.

"We can't do a study to expose smokers to the virus to prove the point because that would be clearly unethical."

Smoking's relationship with Covid-19 fanned the flames of much controversy since the sale of tobacco products was banned when the government enforced a lockdown.