Answered by SecondMedic Expert
General Physician · Infectious Disease
The severity of a flu virus’s infection largely depends upon the characteristics (virulence factors) of the virus itself, as well as the individual person infected. Viruses that possess more virulence factors tend to cause more severe infections than those with fewer or less virulent properties. For example, certain types of flu viruses contain an extra gene segment which codes for proteins that help increase the ability of the virus to spread within cells, leading to increased severity in symptoms. Additionally, other types may include extra surface proteins called hemagglutinins and neuraminidases that can better bind to cells lining respiratory tracts, further exacerbating symptoms.
Individual risk factors can also contribute to a severe influenza-like illness; these include having weakened immune systems due to underlying medical conditions such as HIV/AIDS or cancer treatments like chemotherapy or radiation, age (children under 5 and adults over 65 are at greater risk), obesity and smoking status all play a role in determining how severely you could experience your infection if infected with an influenza virus. In summary, there is no one answer as both viral properties as well as individual differences can lead to varying levels of severity when it comes to influenza infections!
