Abstract. Since the pandemic COVID-19 began in December 2019 in the city of Wuhan in China, scientists were wondering why the infectious disease is more deadly in people with obesity, even if they are young. A number of clinical studies have reported that many of the sickest COVID-19 patients have been people with obesity and the association is also pronounced even in people who are merely overweight. Similarly, smoking is a known health risk factor for many respiratory infections and respiratory diseases. Recently public health experts (WHO, 29 April 2020) found that smokers are more likely to develop severe disease with COVID-19, compared to non-smokers. Similarly, scientific studies have been shown that electronic cigarette smoking (e-cigarette, vaping) is a risk factor for more severe forms of COVID-19. Scientific research found that there are similarities and differences between COVID-19 and the common flu. Influenza (Flu) and COVID-19 are both contagious respiratory illnesses caused by different viruses. In the last decades, influenza spreaded around the world in yearly outbreaks, resulting in about 3-5 million cases of severe illness and about 290,000 to 650,000 deaths worldwide. But COVID-19 is more infectious and more deadly. After 10 months from the first cases, up to 26/10/2020, deaths 1,159,831 (4%) out of 43,4 million cases of infection worldwide. Now there are more statistical data for comparison of both types of viral infections. Medical practitioners and pathologists in hospital intensive care units, realised that people with comorbidities (obesity, cardiovascular diseases, diabetes, hypertension; etc, and smokers) are at increased risk of COVID-19 infection with severe outcome and at high risk of dying for patients over 65 and males. The warning for obesity and risk of dying from COVID-19 was reported by many medical national and international authorities. The USA has the highest rates of obesity and overweight in the world (around 40% for men). This can be a reasonable explaination for the high rate of deaths in the USA during the COVID-19 pandemic.