Analyzing the role of smoking in viral recovery

COVID-19 brought about lasting changes that are still being felt today in the post-pandemic era, with one being the unprecedented side effect known as Long COVID.

Long COVID is characterized by symptoms affecting multiple organs and persisting for at least three months or longer after a COVID-19 infection. It has often been reported to be associated with advanced age, being female, obesity, and having other underlying conditions. However, there has not been a clear conclusion in its relation to smoking.

A research group led by graduate student Erika Toyokura, Dr. Kazuhiro Yamada, and Associate Professor Kazuhisa Asai at Osaka Metropolitan University's Graduate School of Medicine conducted an analysis of the relationship between Long COVID and tobacco use.

They classified participants into five categories, non-smokers, former users, combustible cigarette (CC) users, heated tobacco product (HTP) users, and dual users, based on data from the JASTIS 2023, a nationwide internet survey involving 34,000 participants, with 28,250 included in the analysis and 5,068 with a history of COVID-19.

The analysis results revealed that current smokers were more associated with four symptoms, arthralgia, chest pain, dyspnea, and dysosmia, than non-smokers. In dual users, five symptoms, arthralgia, chest pain, dyspnea, dysgeusia, and dysosmia, were common. CC users correlated with three symptoms, chest pain, dyspnea, and dysosmia, while HTP users suffered from symptoms of dyspnea and sexual dysfunction.

Further, Long COVID symptoms may also be affected differently depending on the type and habits of smoking. It is suggested that the added concurrent use of combustible and heated tobacco products may worsen symptoms.

This study is the first to reveal that Long COVID differs depending on smoking patterns. Specifically, individuals who use both combustible and heated tobacco products showed a stronger correlation with more symptoms. These findings underscore the importance of ceasing tobacco use."

Erika Toyokura, Graduate Student, Graduate School of Medicine, Osaka Metropolitan University

Professor Asai concluded, "Going forward, we plan to examine the causal relationship and underlying mechanisms between smoking and Long COVID symptoms, and apply these findings to public health policies and clinical practice."