Smoking is known to weaken the immune system, making it less able to respond effectively to infections. Smokers may also already have lung disease or reduced lung capacity which would greatly increase the risk of serious illness.

The virus that causes COVID-19 is believed to have spread from animals to humans, and a handful of animals have tested positive in Hong Kong.
But officials believe this is a unique case because Nadia became sick after exposure to an asymptomatic zoo employee, Paul Calle, chief veterinarian at the Bronx Zoo, told Reuters. Calle said they did not know which employee infected the tiger.

“This is the first time that any of us know of anywhere in the world that a person infected the animal and the animal got sick,” Calle said, adding that they planned to share the findings with other zoos and institutions. “Hopefully we will all have a better understanding as a result.”

“We found that countries without universal policies of BCG vaccination, such as Italy, the Netherlands, and the United States, have been more severely affected compared to countries with universal and long-standing BCG policies,” noted the researchers led by Gonzalo Otazu, assistant professor of biomedical sciences at NYIT.