Another limitation is that, due to the qualitative nature of our synthesis and the diversity in study designs, populations, and outcomes, a formal quantitative analysis or meta-analysis could not be performed
A review of studies by public health experts convened by WHO on 29 April 2020 found that smokers are more likely to develop severe disease with COVID-19, compared to non-smokers
Haller H, Ito S, Izzo JL Jr, Januszewicz A, Katayama S, Menne J, et al
Health Affections Although cannabis is becoming increasingly recommended by doctors and scientists after they come to the conclusion that marijuana is a much safer alternative to opioids, for example, we have to admit it still comes along with some side health issues
PMC 5799738