Why obesity, hypertension, diabetes, and ethnicities are common risk
factors for COVID-19 and H1N1 influenza infections
Obesity, hypertension, diabetes, and specific ethnicities (Black and
Hispanic) have been reported to be common comorbidities and possible
risk factors for the severity of both COVID-19 and H1N1 influenza
infections. Thus, it is important to understand why these four risk
factors are common to both COVID-19 and H1N1 influenza infections, and
whether a common mechanism exists. Respiratory failure is the most
important pathology that contributes to the severity of both COVID-19
and H1N1 influenza infections. Additionally, obesity has been reported
to be a risk factor for the development of acute respiratory distress
syndrome (ARDS), which is a serious clinical manifestation of both
COVID-19 and H1N1 infections. Obesity is a risk factor for hypertension.
Most of the previous studies showing hypertension as a risk factor for the severity of COVID-19 and H1N1 infections were either not based on multiple logistic regression analyses or did not include obesity or BMI as an explanatory variable in their multiple logistic regression models. Moreover, similar attention is needed when specifying patients
with diabetes or of specific ethnicities (Black and Hispanic) as
potentially more vulnerable to either infection, because obesity also
correlates with diabetes, and is more prevalent in these ethnicities.
Notably, a retrospective cohort study has shown that obesity or high BMI
are predictive risk factors for severe COVID-19 outcomes, independent of
age, diabetes, and hypertension. Associations between hypertension,
diabetes, ethnicities and severity of COVID-19 and H1N1 infections may
be confounded by obesity to a considerable extent.