Smoking and drinking depress the immune system and so could reduce the effectiveness of vaccines for illnesses such as the flu and coronavirus, according to a senior Turkish physician.

Dr. Cevdet Erdol from the Health Sciences University in the Turkish capital Ankara told Anadolu Agency on Saturday that the use of tobacco and alcohol is harmful to health and could negatively affect treatments, adding that cigarette smoke alters immune responses.

"In studies done more than 40 years ago using simpler methods than today's techniques, the immune response after vaccination in smokers was found to be weak," Erdol said.

Erdol said a study now being done in Australia found that “smokers were significantly more susceptible to the epidemic influenza than non-smokers. In these and similar studies, there is strong evidence that smoking weakens immune response."

Another study, he said, found that exposure to cigarette smoke impairs "the ability to form memory cells that are critical to the maintenance of the protective immune response induced by vaccines."

"It has also been scientifically proven that alcohol use disrupts the targeted immune stimulation achieved by vaccines," he added.

"As the impairments in the immune systems are in basic functions, the same results are also valid for the COVID-19 vaccination process. Alcohol consumption causes liver fattening and impairs liver functions, and both conditions negatively affect the course of COVID-19," he added./aa