Number of smokers catching coronavirus is ‘lower than expected’, scientists say

Scientists have previously commented on 'bizarrely strong' evidence for smoking's protective effect against Covid-19.

A review of scientific studies has found that smokers may be less likely to contract coronavirus.

Researchers at University College London looked at 28 papers with data on people who test positive with the virus and are hospitalised with it and found the number of smokers among them was ‘lower than expected’.

However, smokers who did end up in hospital with the virus appeared to suffer more severely.

It has been suggested nicotine could have a protective effect, although the UCL researchers stressed the ‘substantial uncertainty’ around their findings due to the way smoking habits had been recorded.

Experts have warned that the wider dangers of tobacco still far outweigh any benefits, and studies have found both vaping can also impair the lungs’ ability to fight off infections.

Of the 28 studies analysed, 22 were conducted in China, three in the US, one in Korea, one in France and one internationally using mainly UK data.

That study found five per cent of Covid-19 patients in the UK were current or former smokers, who make up 14.4 per cent and 25.8 per cent of the overall population respectively.

For all the latest news and updates on Coronavirus, click here.

For our Coronavirus live blog click here.

In China, where around half the population light up regularly, just 3.8 to 17.6 per cent of coronavirus patients in hospitals were current smokers.

Some, but not all, of the US findings bucked the trend, recording more smokers among Covid patients in the community and hospitals than the national average.

The French study found the rate for current smokers to be four times lower, although the rate for former smokers was twice as high.

Commenting on the paper on Good Morning Britain today, Linda Bauld, professor of public health at the University of Edinburgh, said ‘there’s something weird going on with smoking and coronavirus’.

‘We know for decades that smoking is linked to a higher risk of developing respiratory conditions and also people who smoke have poorer outcomes.

‘And we’ve still got around seven million smokers in the UK, [the] leading preventable cause of death.

‘However, my colleagues at UCL… what they’ve found is there are surprisingly few smokers in those studies who’ve developed coronavirus.’

Prof Bauld suggested a ‘biological explanation’ could be that nicotine could make it more difficult for the virus to overwhelm the lungs.

The coronavirus mainly sneaks into cells through a specific type of receptor called ACE2.

Some evidence suggests smokers have more ACE2 receptors, making them more prone to catching the virus. However other studies indicate that nicotine weakens the action of the receptors.

Professor Bauld said: ‘It’s plausible that smokers are less likely to develop the condition potentially because of nicotine. Importantly in that UCL review where smokers did develop COVID-19, their outcomes are far worse.’

Commenting on an earlier review of Chinese studies conducted by New York University researchers, another UCL academic said the evidence of smoking’s protective effect against Covid-19 was ‘bizarrely strong’ and ‘actually far stronger than for any drug trialled at this stage’.

Get in touch with our news team by emailing us at webnews@metro.co.uk.

For more stories like this, check our news page.