The various risk factors that have been linked to an increased risk of severe coronavirus disease 2019 (COVID-19) or mortality include comorbidities such as cardiovascular disease, high blood pressure, diabetes, and chronic respiratory disease. To date, few studies have looked at other risk or protective factors associated with symptomatic and asymptomatic COVID-19.
A recent study published on the preprint server medRxiv* discusses a systematic investigation of both known and unknown factors that can influence the risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19, and a severe course of COVID-19.
To learn: Effects of 105 biological, socio-economic, behavioral, and environmental factors on the risk of SARS-CoV-2 infection and severe course of Covid-19: A prospective longitudinal study. Image Source: Drazen Zigic / Shutterstock.com
About the study
Here, researchers conducted a large prospective longitudinal study of 5,164 subjects in the Czech Republic who had no history of COVID-19 before the fourth surge in cases in that country. Of the 5,164 respondents, 1,746 were men and 3,411 women, while 7 subjects did not answer the question about their gender. These subjects shared their information online about their exposure to 105 different risk factors.
At the time of the study, 13.7% (709) of the subjects contracted SARS-CoV-2, while the remaining 86.3% (4,455) did not. Women were comparatively less infected than men, although this difference was more significant when checked for age and urbanization. Both men and women who had COVID-19 reported that they suffered more physically and mentally than those who escaped infection.
To determine the biological, socio-economic, behavioral and environmental factors that influence the risk of SARS-CoV-2 infection and severe COVID-19, the researchers used separate partial Kendall correlation tests that were classified by age, gender and degree of urbanization with factors Controlled as independent factors, and dependent variables, including SARS-CoV-2 infection, COVID-1 progression, symptom severity, duration of infection, and physical and mental health indices.
The protective or risk factors
The 105 potential protection and risk factors examined in this study included gender, age, body mass index (BMI), blood type, rhesus positivity, urbanization, household members, education, family income, children, use of face masks, Washing hands, keeping your distance, eating habits, sports, vitamins, nature walks, animals, depression, illnesses and the use of herbs, among others
Broadly speaking, the researchers grouped these factors into five categories, including:
- Biological factors including morphological features
- Sociodemographic Factors
- Behavioral traits / lifestyle variables
- Contacts with animals
- Use of vitamins and supplements.
While people with higher weight and higher BMI values had a more severe course of the disease, taller and heavier men also had a higher risk of infection than smaller and less heavy men. Interestingly, the study found that the association between infection and height was stronger than the association between infection and weight or BMI. This observation was not found in women.
The researchers also observed that the risk of infection was lower in men and older subjects. This link may be due to the efforts of people who considered themselves at risk to avoid possible sources of infection. This is comparable to the results in patients with other risk factors such as immunodeficiency syndrome or chronic obstructive pulmonary disease.
The authors of the current study also found that the blood group (ABO system) was associated with moderate risks of COVID-19 infection; however, no influence of blood type or Rh factor on the severity of COVID-19 has been reported.
“Our results suggest that the potential impact of the Rh factor on the risk and severity of Covid-19 deserves further attention, but the study of this phenomenon should preferably be based on DNA-genotyped populations as Rh-positive heterozygotes are better and Rh -positive homozygotes have worse health than rhesus-negative people. “
Sociodemographic factors were largely in line with previously published data and had a moderate impact on the risks of COVID-19. Pets in particular (dogs and cats) had no impact on the risk of infection and the risk of severe COVID-19 illness, although previous studies have shown the risk of virus transmission from animals.
Although all medical care, with the exception of non-essential dental treatments in the Czech Republic, is covered by compulsory health insurance, those with higher incomes were likely to invest more in disease prevention as their income was positively correlated with their mental and physical health.
In the current study, the researchers found that active participation in exercise and cold water swimming increased the risk of infection. This is comparable to other studies that have shown that physical inactivity poses a risk for COVID-19. The researchers concluded that this association likely suggests that physical activity is a risk factor for SARS-CoV-2 infection, but not severe COVID-19.
According to previous observations, the strongest protective factor against COVID-19 infection was strict adherence to masks and breathing apparatus, with the second strongest protective factor being the intake of vitamins and dietary supplements. However, anxiety and depression, especially in women, were a risk of infection.
Interestingly, the researchers found unexpected and potent protective effects against infection and severe COVID-19 in those who have been previously diagnosed with Lyme disease or who reported drinking rooibos. The immunoregulatory activity of the extracellular parasite Borrelia could confer immune protection against SARS-CoV-2 and a cytokine storm.
Rooibos, not a herbal drink, is a fermented extract made from the leaves of Aspalathus linearis. This drink has both antioxidant and anti-inflammatory properties, both of which can play a role in its protective effects against SARS-CoV-2. So far, no data on rooibos and COVID-19 are available.
medRxiv publishes preliminary scientific reports that are not peer-reviewed and therefore are not considered conclusive, guide clinical practice / health-related behavior, or should be treated as established information.