Research into interplay between COVID-19 and smoking conducted by the Council of Scientific and Industrial Research (CSIR) has been questioned by scientists. The CSIR serosurvey reportedly suggested that smokers are at lower risk of contracting COVID-19 – but experts responded with doubts.
The CSIR conducted a seroprevalence survey of 10,427 Indians, consisting of those working in CSIR laboratories or institutions and their relatives. As explained by the U.S. Centers for Disease Control and Prevention (CDC), “serology tests look for antibodies in blood. If antibodies are found, that means there has been a previous infection. Antibodies are proteins that can fight off infections. Investigations using serology testing are called seroprevalence surveys.”
Seroprevalence surveys are used in the context of COVID-19, the CDC explains, “to identify people in a population who have antibodies against SARS-CoV-2 [severe acute respiratory syndrome coronavirus 2, the novel coronavirus which causes COVID-19]. Antibody test results can provide information about previous infections in people who had many, few, or no symptoms.”
The CSIR’s seroprevalence survey found, it said, that smokers are less likely to be seropositive than non-smokers. This, it said, “is the first report from the general population and part of growing evidence that despite Covid-19 being a respiratory disease, smoking may be protective.”
However, scientists have repudiated the findings in comments to The Print. “We have not found such evidence in our hospital of smokers having any protection from COVID as this serosurvey suggests,” said Dr B. L. Sherwal, medical director of the Rajiv Gandhi Superspecialty Hospital. “But we have seen that smokers have higher susceptibility to COVID infection. This is because their immune system is compromised and their lungs are already affected by smoking. Seroprevalence may have been lower because antibodies may disappear due to slow immune response among smokers.”
In concurring sentiments expressed to The Print, Public Health Foundation of India president Dr K. Srinath Reddy said “there are several explanations for why smokers haven’t shown presence of antibodies against Covid. Antibody levels may disappear faster among smokers compared to non-smokers. Presence of antibodies is also dependent on multiple factors like nutrition and age.”
As The Print noted, “in July last year, the Union Health Ministry had said smokers were likely to be more vulnerable to COVID-19 as smoking increases possibility of transmission of virus from hand to mouth, and warned that use of tobacco products could increase severity of respiratory infections and make people susceptible to coronavirus.”
Last year, Health Issues India reported on the interplay between COVID-19 and smoking and other forms of tobacco use. We cited comments made by interventional pulmonologist Dr Prem Ananth P., who said “though there is no direct evidence showing those who consume tobacco are more prone to COVID-19, poor respiratory health due to tobacco-caused chronic obstructive pulmonary disease (COPD) can in turn aggravate if infected by COVID-19.” We also cited the World Health Organization (WHO), who said “smoking impairs lung function making it harder for the body to fight off coronaviruses and other diseases.
“Tobacco is also a major risk factor for noncommunicable diseases like cardiovascular disease, cancer, respiratory disease and diabetes which put people with these conditions at higher risk for developing severe illness when affected by COVID-19. Available research suggests that smokers are at higher risk of developing severe disease and death.”
Indeed, the WHO in December used COVID-19 as a linchpin of its bid to urge tobacco users to kick the habit. Director-General Dr Tedros Adhanom Ghebreyesus said at the time “smoking kills eight million people a year, but if users need more motivation to kick the habit, the pandemic provides the right incentive.” The WHO observed that “when evidence was released this year that smokers were more likely to develop severe disease with COVID-19 compared to non-smokers, it triggered millions of smokers to want to quit tobacco. Quitting can be challenging, especially with the added social and economic stress that have come as a result of the pandemic, but there are a lot of reasons to quit.”
India is no stranger to the detrimental effects of tobacco use among the population. According to the Tobacco Atlas, “every year, more than 932,600 of [India’s] people are killed by tobacco-caused disease. Still, more than 625,000 children (ten to fourteen years old) and 89,486,000 adults (fifteen+ years old) continue to use tobacco each day.” As noted by Health Issues India, “tobacco use fuels the country’s crisis of noncommunicable diseases, which result in 5.2 million lives lost a year. And, as the WHO points out, a high rate of tobacco use stands to exacerbate India’s ongoing COVID-19 crisis as well as other diseases prevalent in India such as tuberculosis.”
As far as the CSIR study regarding COVID-19 and smoking goes, the evidence simply isn’t there to support the notion that smoking has a protective effect against COVID-19 – and, in many cases, research points to the conclusion that the opposite is plausibly true. “Smoking always impacts health because it inhibits antibody response and suppresses immunity,” Dr Lalit Kant, the former head of epidemiology and infectious diseases at the Indian Council of Medical Research, told The Print. “We cannot derive conclusions from such studies and a detailed epidemiological study is required to establish cause and effect relations instead of a cross-sectional study such as this.”