A review of 28 studies has found that the proportion of smokers appear to be lower than non-smokers among hospitalised COVID-19 patients, reported Hindustan Times.
The research by academics from University College London and Royal Veterinary College, London included 22 studies conducted in China, three in the United States, one in South Korea, one in France and one across multiple international sites with data predominantly collected in the United Kingdom.
The UK study showed that the proportion of smokers among COVID-19 patients was just 5 per cent, a third of the national rate of 14.4 per cent.
Similarly, the French study found that the rate of smokers was four times lower. In China, a study revealed that just 3.8 per cent of patients were smokers compared to more than half of the population who regularly smoke cigarettes.
The two studies in the review showed that when smokers test positive for the virus, the complications are likely to become so serious that they require ventilation support.
“Across 28 observational studies, there is substantial uncertainty arising from the recording of smoking status on whether current and/or former smoking status is associated with SARS-CoV-2 infection, hospitalisation or mortality,” concluded the “pre-print” paper published on the study-sharing website Qeios.
“There is low-quality evidence that current and former smoking compared with never is associated with greater disease severity in those hospitalised for COVID-19,” wrote authors Lion Shahab, Jamie Brown and Olga Perski of UCL and David Simons of Royal Veterinary College.
The researchers said the majority of the 28 studies reported current and/or former smoking status but had high levels of missing data and/or did not explicitly state whether the remaining participants were never smokers.
But despite these uncertainties, compared with national prevalence estimates, recorded current and former smoking rates in the included studies were generally lower than expected, said the study.