Antibodies from the Covid vaccine decrease faster in smokers

Smoking negatively impacts the body’s response to Covid vaccines. This is what emerges from a review of the scientific literature conducted by researchers from CoEhar (Center of excellence for the acceleration of harm reduction), Center for the reduction of harm from smoking of the University of Catania, in collaboration with the Universities of Pavia and Milan. In 17 of the 23 studies reviewed, smokers showed a lower antibody titer or a faster lowering of vaccine-induced IgG (immunoglobulin G) compared to non-smokers. The result confirms a data released in January in a previous study (called “Vasco”), which showed how the antibodies induced by the anti-Covid vaccine decrease faster in smokers.

Altered immune response

“Although the mechanisms underlying the antibody data extrapolated from the complexity of the immune response to vaccines are not well known – says Pietro Ferrara, one of the authors of the study, epidemiologist and researcher at the University of Pavia -, these results seem to confirm yet another impact negative effects of smoking on human health and on alterations in the immune response to vaccines, weakening the body’s defenses against the clinical consequences of infections ». «The smoking habit influences the proliferation of lymphocytes and other cells of the immune system – adds Professor Riccardo Polosa, founder of CoEhar -. Smokers respond less to vaccines e they are therefore more at risk. Identifying the elements that can influence their response is essential to evaluate their effectiveness and duration and any therapeutic precautions. We need more answers and we are continuing to work on this ».

Eight million dead

In 2019, 1.1 billion tobacco users were registered in the world and smoking represents one of the most important causes of illness and premature death. It is responsible for 8 million deaths and 200 million years of “disabled life expectancy” (disability-adjusted life year or Daly, a measure of disease severity) every year globally: a huge challenge for health systems. The consequences of smoking include a wide range of diseases: lung cancer, chronic obstructive pulmonary disease (BPCO), cardiovascular disease, viral and bacterial infections of the respiratory system. Smoking affects the immune system: in particular, there is evidence of an association between cigarette smoking and the higher risk of several diseases, ranging from autoimmune (such as allergies or transplant rejection) to systemic inflammatory ( for example rheumatoid arthritis), to a lower protection against external antigens and therefore against infections.

Further studies are needed

Some studies prior to that of CoEhar have described a link between smoking and lower levels of vaccine-induced antibodies (e.g. after immunization against hepatitis B and boosters against tetanus and diphtheria), or a lower “strength” of immunoglobulin G (IgG) in smokers (in the case of the adjuvanted vaccine for human papillomavirus types 16 and 18). In contrast, another flu vaccination study suggested that smoking does not interfere with the amount of vaccine-induced antibodies. On the link between smoking and response to vaccines, the Italian researchers underline, there are still no conclusive results. Also due to the presence of many confounding factors: in the 23 papers analyzed by the Italian team, the extent and timing of the antibody drop attributable to smoking varies considerably between studies, depending for example on the type of serological test used and the time elapsed since vaccination. .

Innate and adaptive defenses

However, the researchers explain, most of the current evidence suggests that smoking has a negative impact on the reaction to Covid vaccines, with less immune response and faster lowering of vaccine-induced IgG titers than non-smokers. The negative effects of smoking on the immune system appear to be caused by several mechanisms, which affect both innate and adaptive immunity. Some studies indicate a direct effect of smoking on changes in the number of immune cells (including monocytes, macrophages, dendritic cells and lymphocytes). Previous investigations have shown that smoking induces inflammatory cytokines and chemokines. In cigarette smokers, T cells also exhibit defective responses of adaptive immunity. In addition, Ig analyzes revealed decreased production of IgA, IgG and IgM associated with smoking.