Heated tobacco products associated with COVID infection and severity in Japan; dual use is worse

It is well-established that smoking makes COVID-19 worse once you are infected, but the relationship between smoking and COVID infection is not as clear, due to the fact that most studies have not been based on population representative samples. Instead, most have been of tested people at a time that testing was limited and so are subject to concerns about sampling bias. There have also not been any studies of the association between use of heated tobacco products (HTP, such as IQOS, Ploom, glo and others).

This situation is changing. Misako Nishimura and colleagues recently published “Association of combustible cigarettes and heated tobacco products use with SARS-CoV-2 infection and severe COVID-19 in Japan: a JASTIS 2022 cross-sectional study,” a population-based study of the association between heated tobacco products that have been widely available in Japan for years as well as combusted cigarettes. (e-cigarettes are not legal there and usage is low.)

Using a large nationally-representative sample collected in February 2022, they found that current HTP use significantly increased the odds of COVID-19 infection by a factor of 1.65 and dual use with combusted cigarettes increased the odds of infection by a whopping factor of 4.66.

Among people with COVID, HTP use and dual use were also associated with more serious disease, indicated by need for supplemental oxygen.

Current or former use of combusted cigarettes alone was not significantly associated with COVID infection risk. Consistent with the earlier literature, current or former use of cigarettes was associated with more serious disease.

These results are similar to a much smaller US study of youth and young adults who use e-cigarettes.

The results on dual use are particularly interesting because dual use — currently using both HTP and cigarettes — is common. HTP expose users to many toxins not in cigarette smoke and it may be that the combined exposure to HTP and cigarettes is increasing the overall toxic load.

This is another reason we need to pay more attention to dual use and stop assuming, as the FDA does, that dual use is no worse than smoking.

Here is the abstract:

Insufficient evidence has been accumulated regarding associations of heated tobacco products (HTPs) use with coronavirus infection and severity of coronavirus disease 2019 (COVID-19), an ongoing pandemic. We conducted a cross-sectional study using data from an internet questionnaire administered in February 2022 to 30,130 individuals from the general Japanese population (age range, 16-81 years). Single users of HTPs and dual users of combustible cigarettes and HTPs comprised 5.2% and 7.3% of respondents, and 6.7% and 38.0% of those infected (n = 1117). Approximately 70% of infected dual users experienced severe disease. Single users of HTPs and dual users were more likely to be infected with coronavirus than never-users (adjusted odds ratio [aOR] = 1.65/4.66; 95% confidence interval [CI] 1.26-2.15/3.89-5.58). Regarding severity, former and current tobacco users (former/combustible cigarettes/HTPs: aOR = 1.88/3.17/1.90; 95%CI 1.11-3.19/1.77-5.67/1.01-3.59) were more likely to be administered oxygen than never-users, and dual users required oxygen administration the most (aOR = 4.15, 95%CI 2.70-6.36). Use of HTPs may increase risks of coronavirus infection and severe COVID-19. Our results provide an opportunity to consider the safety of tobacco products use, including HTPs, during the COVID-19 pandemic.

The full citation is Nishimura M, Asai K, Tabuchi T, Toyokura E, Kawai T, Miyamoto A, Watanabe T, Kawaguchi T. Association of combustible cigarettes and heated tobacco products use with SARS-CoV-2 infection and severe COVID-19 in Japan: a JASTIS 2022 cross-sectional study. Sci Rep. 2023 Feb 2;13(1):1120. doi: 10.1038/s41598-023-28006-3. PMID: 36732559; PMCID: PMC9894839; it is available here.