Exploring the biological mechanisms, statistical evidence, and recovery strategies connecting tobacco use with severe COVID-19 outcomes.
When the COVID-19 pandemic swept across the globe, a crucial question emerged among scientists and health professionals: how would smoking, another serious global public health problem, influence the course of this new disease?
Smoking not only increases the risk of serious COVID-19 complications but creates unique routes for virus transmission. This relationship is more than a simple coincidence of risk factors.
Smoking fundamentally alters lung biology, the immune system, and even behaviors that increase vulnerability to coronavirus. Understanding these connections is vital for saving lives and guiding public policies.
Research reveals that the smoker's lung has, in large quantity, a specific type of cell that produces mucus to protect the lung walls from cigarette toxins. The problem is that this cell has a substance that functions as an anchor for the coronavirus, allowing not only infection but facilitating deeper penetration of the virus into the lung 6 .
Additionally, a person who smokes has less lung capacity than a non-smoker. When viral pneumonia occurs, the parts affected by the virus will be more critical, requiring more mechanical ventilation and more days in the ICU 6 .
Lung Capacity Comparison Visualization
Tobacco causes different types of inflammation in the body, impairing defense mechanisms and increasing susceptibility to infections by viruses, fungi, and bacteria 5 . Smoking:
Immune Response Comparison Visualization
| Mechanism | Effect on the Organism | Consequence in COVID-19 |
|---|---|---|
| Cellular alteration in the lung | Increase in cells with "anchor" for the virus | Greater viral penetration and replication |
| Reduced lung capacity | Less respiratory reserve | Greater need for mechanical ventilation |
| Immune compromise | Deficient response to pathogens | Greater difficulty fighting infection |
| Increased coagulation | Blood more prone to clots | Increased risk of thrombosis and embolisms |
| Chronic inflammation | Basal pro-inflammatory state | More severe cytokine storm |
45%
Higher chance of complications from COVID-19 in smokers
Study by the President of the São Paulo Society of Pulmonology and Phthisiology 6
88%
Higher complication risk in smokers with chronic lung disease
Systematic review and meta-analysis 6
| Clinical Outcome | Risk Increase in Smokers | Source of Evidence |
|---|---|---|
| General complications | 45% higher | Systematic review and meta-analysis 6 |
| Hospital mortality | 38% higher | Systematic review and meta-analysis 6 |
| Progression to severe forms | 14 times higher | Research on disease progression 5 |
| Complications in smokers with lung disease | 88% higher | Systematic review and meta-analysis 6 |
Early in the pandemic, misleading information circulated that nicotine might have a protective effect against COVID-19. This myth emerged from an article deposited in a repository without adequate curation, whose authors did not declare conflicts of interest - although one of them had previously worked directly for the tobacco industry 6 .
To clarify this issue, researchers conducted a systematic review with meta-analysis - methodology considered high scientific evidence - that analyzed multiple studies on smoking and COVID-19 6 . Unlike the previous questionable work, this analysis:
The results were categorical: smoking is associated with negative progression and adverse effects of COVID-19 6 . When interpreting the literature appropriately, the result is the opposite of what was initially propagated by fake news.
This study was crucial for:
| Aspect | Original Study with Problems | Reliable Meta-Analysis |
|---|---|---|
| Method | Limited observational analysis | Systematic review with meta-analysis |
| Curation | Repository without rigorous peer review | Adequate peer review process |
| Conflict declaration | Not declared | Transparent |
| Results | Possible protective effect of nicotine | Smoking associated with 45% more complications |
| Policy impact | Potentially misleading | Informative for public health |
The World Health Organization (WHO) encourages people to quit smoking to minimize risks associated with the COVID-19 pandemic, both for smokers and people exposed to secondhand smoke 1 . Benefits begin quickly: lungs already function better after just 12 hours without cigarettes 5 .
In Brazil, where cigarettes still cause 174,000 deaths per year and generate R$ 153.5 billion in costs 2 , the Unified Health System (SUS) offers treatment that includes clinical evaluation, minimal or intensive approach, individual or group therapy and, if necessary, drug therapy .
"Studies show that even a brief conversation of 30 seconds to 3 minutes between health professionals and smokers during routine consultations can be the starting point to prevent smoking initiation or lead to smoking cessation."
Other effective strategies include:
Mark a date to quit smoking, creating a clear objective 5
Gradually reduce the number of cigarettes before the established date 5
Identify and avoid triggers that spark the desire to smoke 5
Seek social support from friends, family, and support groups 5
Use available resources like the short support videos created by INCA for smoking treatment 1
The dangerous intersection between smoking and COVID-19 creates not only risks but also unique opportunities for public health intervention. Understanding the multiple mechanisms behind this connection - from cellular changes in the lungs to behaviors that facilitate transmission - provides powerful tools to face both crises.
The final message is clear and based on solid evidence: quitting smoking is one of the most effective measures to reduce the risk of serious complications from COVID-19.