Studies have shown that people who have optimal Vitamin D levels are less likely to Experience Common Colds, Asthma and Respiratory tract infections. In fact, upper respiratory tract Infections are inversely associated with LOW SERUM [BLOOD] LEVELS of Vitamin D!
In addition, a 27yrs old HIV infected woman diagnosed during antenatal care, she was not eligible for anti-retroviral therapy but was therefore placed on black Cumin oil and honey mixture (10mls/3x daily).
Her repeat serology for HIV infection became negative with undetectable viral load, a whopping CD4 count of >750cells/πL!!! [Onifade et al]
Here, you see the effect of Black Seeds on microbes like Viruses is next to none.
However, Medicinal herbs like Cumin are safer with lesser side effects than conventional drugs.