"So, that infection can land on the lungs a lot easier, which is one of the issues with Covid-19.
"We also know that smoking is associated with blood pressure, heart disease, and a number of other conditions which produce poorer outcomes with Covid-19."
World Health Organisation Director-General Dr Tedros Adhanom Ghebreyesus last year warned smoking increased the severity of respiratory diseases and make people more likely to get gravely ill from Covid-19.
"Smokers have up to a 50 per cent higher risk of developing severe disease and death from Covid-19, so quitting is best thing smokers can do to lower their risk from this coronavirus, as well as the risk of developing cancers, heart disease and respiratory illnesses," he said.
And a study by researchers from King's College London suggested smokers who contracted Covid-19 were twice as likely to need hospital care and tended to report more symptoms from non-smokers.
But research has also found about half of smokers surveyed in New Zealand, Australia and the UK had heard little or nothing about the Covid-19 risks for them.
Quitline service manager Jordan Taiaroa said the number of people wanting to stub out the habit for good increased in the last three months of 2021.
"We did see a rise of about 250 people coming into the service," he said.
"We can attribute that to different things: The New Year's resolution period that everyone aims to try and quit by, and also the recent lockdown that had just ended and people being motivated to either continue what they were doing throughout the lockdown of quitting smoking, or quitting after the lockdown."
Almost 28,000 people were enrolled with Quitline's services in the year ending June 2021, Taiaroa said.
New Zealand's smoking rates are dropping: 10.9 per cent of adults are smokers, but that is higher among Māori and Pasifika: 25 per cent for Māori and 19 per cent for Pasifika.
And the pandemic isn't helping. Researchers last year found people who felt distressed and lonely during the country's first lockdown were three times more likely to smoke more.
Lealailepule Edward Cowley, from Hāpai te Hauora, said stress levels were high, and people trying to quit needed support.
"It's a whole community approach that is going to get people over the line, because those people that are going to go to Heaven too early are our brothers, sisters, mother, uncles, cousins, members of our family," he said.
"So, if someone in my family was in that position, it would be incumbent on me to be able to have that conversation, to support them, or try and motivate a quit attempt from them, because I want to keep them around longer.
"The more conversations we're having within our families, within our community, the easier it's going to be for people to access services they've never been able to do in the past, because now we have an abundance of options."
Action for Smokefree 2025 (ASH) chairperson Emeritus Professor Robert Beaglehole said smoking cessation programmes were doing all the right things - but they needed to be more ingrained in people's lives.
"There are still 380,000 people who smoke on a daily basis and they all need support, encouragement, and understanding to help them make that transition away from smoking cigarettes, perhaps in the first instance to less harmful products, and then eventually, to be smokefree themselves," Beaglehole said.
"There's no point punishing people, blaming them, telling them what to do, we have to get alongside them in their communities. And there's much more we can do in that regard."
Beaglehole said more investment in community outreach programmes to support people who smoke alongside mass media campaigns promoting smoking cessation services would go a long way.
"It's very hard to stop smoking. We need more people to make more quit attempts more often, and we need to help them," he said.
Smokers should also be encouraged to switch cigarettes for traditional nicotine replacement therapies, like patches, gum and vaping on the road to becoming smokefree, he said.
