The COVID-19 pandemic highlighted factors influencing disease susceptibility and severity. Smoking has long been known for its detrimental effects, especially on the respiratory system. This article examines how smoking influences an individual’s risk and ability to combat COVID-19.
Smoking’s Impact on COVID-19 Risk
Smoking influences both the likelihood of contracting SARS-CoV-2 and the severity of COVID-19. Studies indicate that current and former smokers face a higher risk of developing severe outcomes from COVID-19, including increased rates of hospitalization, admission to intensive care units (ICU), the need for mechanical ventilation, and mortality. Compared to non-smokers, individuals who smoke and contract COVID-19 are 3.25 times more likely to experience severe and critical illness.
Smoking compromises the respiratory system, rendering it more vulnerable to viral entry and damage. Cigarette smoke can damage cilia, which are tiny, hair-like structures lining the airways that typically trap viruses and debris, sweeping them out of the lungs. When cilia are impaired, they are less effective at preventing the virus from settling into the lungs. Research suggests that cigarette smoke increases the levels of ACE2 (angiotensin-converting enzyme 2) receptors in the lungs, which are the primary entry points for the SARS-CoV-2 virus into human cells. This increase in ACE2 receptors may facilitate greater viral entry and replication, potentially explaining why smokers are more susceptible to severe infections.
How Smoking Weakens Defenses Against COVID-19
Smoking significantly compromises the body’s ability to fight off respiratory infections like COVID-19. Chronic exposure to cigarette smoke leads to chronic inflammation in the lungs, damaging the respiratory epithelial barrier and creating an environment prone to repeated infections. This inflammation can cause thickening and narrowing of airways and destruction of air sacs, leading to reduced lung function.
Beyond direct lung damage, smoking also suppresses the immune system, making it less effective at mounting a robust defense against viral pathogens. Tobacco smoke interferes with immune cells, such as macrophages and lymphocytes, and disrupts antibody production, diminishing the body’s capacity to fight off infections. For example, cigarette smoke is known to reduce the activity of interferons, which are crucial for the body’s early immune response. This compromised immune response exacerbates disease progression.
The Health Benefits of Quitting Smoking
Quitting smoking offers substantial health benefits, improving respiratory health and bolstering defense against infections. Immediate improvements include a rapid drop in heart rate and blood pressure within 20 minutes, with excess carbon monoxide clearing from the blood within a day. Within one to three months, lung function can improve by as much as 30%, and coughing and shortness of breath decrease. The cilia begin to regrow and regain normal function quickly after quitting, enhancing the body’s ability to fight off respiratory infections.
Quitting smoking also strengthens the immune system, which is no longer exposed to harmful toxins. While some aspects of the immune system, such as the innate immune response, recover quickly, the adaptive immune system may take longer to fully rebound. Nevertheless, the overall improvement in immune function reduces the risk of severe respiratory infections, including COVID-19. Even for those who have smoked for decades, quitting can lead to significant improvements, slowing the progression of lung diseases like COPD and reducing the loss of lung function over time.