[Kozak]

for instance - why is it that some people get a cold while others, though exposed to the same pathogen, stay healthy and without a cold or flu?

For a microbiologist you seem to have a pretty shallow knowledge of the subject. For starters how about things like prior exposure to the pathogen with subsequent immunity, exposure to a lower dose of the pathogen allowing a subclinical infection and subsequent acquired immunity, exposure to a weakened strain of the pathogen, variation in genetic suseptability to the pathogen, and temporary fluctuations in immune defences due to other stresses, infections? Just for starters now....

[krodriguesdc]

For a microbiologist you seem to have a pretty shallow knowledge of the subject. For starters how about things like prior exposure to the pathogen with subsequent immunity, exposure to a lower dose of the pathogen allowing a subclinical infection and subsequent acquired immunity, exposure to a weakened strain of the pathogen, variation in genetic suseptability to the pathogen, and temporary fluctuations in immune defences due to other stresses, infections? Just for starters now....

wow you are so smart!

well - you are correct - somewhat - so why have mandated vaccines if naturally aquired immunity is better than vaccinations!

somatic mutations of your immune system repertoire is a biggy yes...

In addition practicing a healthy life style - proper nutrients, exercise, rest, stress reduction, etc.