It seems counter-intuitive, but it may be that smoking confers some sort of benefit regarding COVID:
French researchers want coronavirus patients to wear nicotine patches to study whether it helps prevent or control the disease.
Their review of more than 480 patients with COVID-19 at a large hospital found about 5% of the people to be daily smokers, according to an article on Qeios. An estimated 25% of the French population smoke daily, the researchers said…
The findings are similar to data from China published last month in the New England Journal of Medicine, AFP reported. Out of 1,000 people infected in China, about 12.6% were smokers compared with about 26% in the general population, according to the news outlet.
On reading that, it occurred to me that older people have significantly lower rates of smoking than younger and middle-aged people. Older people also are more likely to have co-morbidities that have caused them to stop smoking, and they are more likely to be the very serious cases that require hospitalization and ICU care and might lead to death.
However, going to what I think must be the actual study (which I always prefer to do if I can find it, because newspaper reports tend to leave out a lot of important information), I noticed that the researchers did correct for age and for sex. So age is not the reason for the lower rates of smoking found.
There were two groups in the study, inpatients and outpatients. Both were compared for rates of smoking to the average French population (adjusted for age and sex):
Eligible patients were those with a confirmed diagnosis of COVID-19 at the APHP Pitié- Salpêtrière Hospital, Paris, France, either hospitalized in medical wards of medicine, but not in ICUs (inpatients) or having consulted for this infection in the infectious disease department and who did not require hospital care until the end of the acute infectious episode (outpatients).
You can see that two other groups were not studied: asymptomatic patients, and those in the ICU. So the study didn’t deal with the mildest or the most severe cases, but it did compare the rates of smoking in mildly symptomatic and somewhat severe (hospitalized) cases to each other and to the ordinary French population in terms of present smoking behavior. The milder and more severe hospital groups both resembled each other, and both featured a great deal less smoking than the matched population. The inpatients in the study tended to be older and to have more co-morbidities, and the listed co-morbidities for the inpatients seemed significantly lower than I’ve read for other studies: hypertension (41.4%), diabetes (27.7%), obesity (14.4%). This could possibly have some significance for the results.
The researchers also write:
…[T]hese studies included mostly hospitalized patients, and the low rate of current smokers may be related to high rate of patients with comorbidities (smokers having been advised to quit) and thus to COVID-19 severity. This could therefore introduce a confusion bias…
…SARS-CoV2 is known to use the angiotensin converting enzyme 2 (ACE2) receptor for cell entry, and there is evidence that nicotine modulates ACE2 expression]which could in turn modulate the nicotinic acetyl choline receptor…
Our findings should be interpreted cautiously and we are aware of its limitations. First, the study was performed in 2020 and the results were compared to data obtained from the French general population’s smoking rate in 2018. However, it is very unlikely that a dramatic decrease in tobacco use may have occurred in France since mid 2018. The SIRs were estimated with the assumption that the studied population who lives in a limited area around a Parisian hospital has the same smoking habits as the general French population. Actually, smoking rates differ across socio-professional categories, and therefore may differ across geographic areas. It should also be noted that in the present study, healthcare workers were over-represented in the outpatient group, due to systematic testing at their work place when they become symptomatic, but not in the inpatient group (data not shown). It is, however, very unlikely that the very low SIRs that were estimated both for the out- and inpatient groups are the result of the study setting. Under or over-reporting of smoking status may also be a concern for studies on smoking habits.
The elimination of ICU patients may be a significant flaw in the study. For example, there’s this:
…[A] study of more than 1,000 patients in China, published in the New England Journal of Medicine, found that smokers with COVID-19 were more likely to require intensive medical interventions than those who didn’t smoke. In the study, 12.3% of current smokers were admitted to an ICU, were placed on a ventilator or died, as compared with only 4.7% of nonsmokers.
It will be a long time before we understand this disease. I don’t think that makes it so very different from a whole lot of other diseases, either. For example, do really understand why H1N1 killed mostly people under 65? The hypothesis was that older people had been exposed previously to a similar virus, but in an admittedly quick search I can’t find any proof of that. One reason we (the public, that is) are not still puzzling over the details of H1N1 infection is that although the H1N1 virus killed a lot people, it didn’t kill quite as many as feared. And then, a vaccine was developed and has been incorporated into regular flu shots). But this was the toll in the pandemic’s first year:
Few young people had any existing immunity (as detected by antibody response) to the (H1N1)pdm09 virus, but nearly one-third of people over 60 years old had antibodies against this virus, likely from exposure to an older H1N1 virus earlier in their lives. Since the (H1N1)pdm09 virus was very different from circulating H1N1 viruses, vaccination with seasonal flu vaccines offered little cross-protection against (H1N1)pdm09 virus infection. While a monovalent (H1N1)pdm09 vaccine was produced, it was not available in large quantities until late November—after the peak of illness during the second wave had come and gone in the United States. From April 12, 2009 to April 10, 2010, CDC estimated there were 60.8 million cases (range: 43.3-89.3 million), 274,304 hospitalizations (range: 195,086-402,719), and 12,469 deaths (range: 8868-18,306) in the United States due to the (H1N1)pdm09 virus.
Additionally, CDC estimated that 151,700-575,400 people worldwide died from (H1N1)pdm09 virus infection during the first year the virus circulated.** Globally, 80 percent of (H1N1)pdm09 virus-related deaths were estimated to have occurred in people younger than 65 years of age. This differs greatly from typical seasonal influenza epidemics, during which about 70 percent to 90 percent of deaths are estimated to occur in people 65 years and older…
On August 10, 2010, WHO declared an end to the global 2009 H1N1 influenza pandemic. However, (H1N1)pdm09 virus continues to circulate as a seasonal flu virus, and cause illness, hospitalization, and deaths worldwide every year.
Also, Obama was president in 2009-2010, which made the press far less likely to criticize our H1N1 response or blow the situation up.
