Symptomatic COVID-19 patients who are unlikely to be smokers

Since the COVID-19 pandemic is raging in many parts of the world, new studies indicate that smoking may not play a significant role in increasing the severity of the disease in these patients. .. The survey is published on the preprint server medRxiv* May 2020.

It is well known that COVID-19 disease-causing virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causes severe lung disease, often causing acute severe respiratory distress and multiple organ dysfunction. I will. Or both, leading to death. Predispositions to serious or significant illness include underlying diseases such as old age, asthma, high blood pressure, diabetes, and cardiovascular disease.

But does active smoking increase the risk? Little is known about the role of this factor that prompted current research.

Smoking can increase virus invasion, is it possible?

Smoking increases expression of the angiotensin converting enzyme 2 (ACE2) molecule in smoker tissues. ACE2 is known to be the major receptor for viral attachment and entry into human host cells. Logically, smoking seems to increase the risk of infection.

The SAV-CoV-2 virus binds to the ACE-2 receptor on human cells, the early stage of COVID-19 infection. Image credit: Kateryna Kon / Shutterstock

Some studies contradict this assumption, but instead show the opposite. For example, in a Chinese study, only about 1.4% to 12.6% of COVID-19 patients are smokers. Similarly, only about 5% of New York patients who are part of a very severe outbreak were smokers.

Compared with the national smoking statistics of both countries, it is about 25% and 17%, respectively. https://worldpopulationreview.com/countries/smokingrates-by-country, These are so low that it turns out there is no easy link. The current study is driven by the need to investigate the existence of an inverse correlation between smoking and possible COVID-19 infection.

How was the COVID-19 smoking study done?

The researchers conducted a retrospective study of approximately 440 patients with COVID-19, all of whom were continuously admitted to a tertiary-level center in Parma, Italy. All of them confirmed infection with a nasopharyngeal swab that proved positive by reverse transcriptase-polymerase chain reaction (rt-PCR).

Investigators extracted demographic, clinical, laboratory, and mortality data from hospital electronic medical records. They also sought to confirm smoking data by direct contact with patients or their relatives in 423 of 441 cases.

What has the smoking study shown about COVID-19?

As a result, about 62% of patients were male, with a median age of 71 years. 35% of patients died during hospitalization and 65% were discharged after clinical recovery.

About 5% of them were active smokers at the time of the survey, but 10% were smokers but quit. The rest were never smokers.

A more detailed analysis of clinical features observed that more men died of this disease. It accounted for 62% of the total number of patients, but only 72% of deaths and 59% of survivors. The median age of those who died was 76, while the age of those who survived was 67. However, this was not statistically significant.

Again, the presence of certain coexisting medical conditions was much more common among the dead. For example, patients with a history of cardiovascular disease accounted for 21% and 10% of those who died and survived, respectively.

Hypertension was present in 61% and 56% of dead and survivors, respectively, while diabetes was present in 26% and 18%, respectively, but these were not significant.

The median value of D-dimer, a marker of inflammation, was almost twice that of deaths compared to survivors. Among those who died, median levels of C-reactive protein were much smaller but with a significant increase, and inflammation was also increased.

However, in smoking, about 6% and 4% of those who died and survived were current smokers, which was not a significant difference. Similarly, the numbers of former smokers and nonsmokers were similar in both groups.

What does this study mean for people exposed to COVID-19?

Italy experiences the second highest COVID-19 mortality in the European Union. However, in this retrospective study, smoking rates are 24% in Italy, compared to the current 5% of patients who smoke. Therefore, this finding is consistent with previous studies in China and the United States.

Conclusions should be limited to hospitalized or symptomatic cases of COVID-19, as the study did not intentionally include asymptomatic patients.

“Current research suggests that smokers may have some mechanism of defense against symptomatic SARS-CoV-2 infections,” the researchers note. As with, only carefully designed control studies can verify this impression.

The mechanism underlying the low prevalence of smoking in this population of hospitalized COVID-19 patients is currently purely speculative. For example, exposure to smoke suppresses the immune response, resulting in lower systemic inflammation than nonsmokers.

Adjusting the normal strength and spectrum of the immune system against the virus reduces the chances of a cytokine storm in COVID-19 patients due to “continuous inflammatory attacks,” resulting in severe or symptomatic disease. It becomes difficult to become.

The importance of identifying the protective role of smoking in this pandemic, researchers say, could help elucidate the underlying molecular mechanisms underlying SARS-CoV-2 infection, It could also potentially be exploited by a newly devised targeted protection drug. ”

*Important Notices

medRxiv It publishes preliminary, non-peer reviewed scientific reports and should not be considered conclusive and should not guide clinical practice / health-related behavior or be treated as established information.