I’ve always thought as long as you were ‘sick’ - i.e. with symptoms like sneezing or coughing - you were infectious / contagious. (My doped-up-on-Dayquil brain won’t let me figure out the appropriate word at this point).
Recently I read that the germs are really only contagious (? see above) for the first few days of a cold. The same article stated that for the first few days of a cold, you don’t actually have any symptoms.
Is this true? So really, you can ‘catch’ a cold and be sick for a few days, during which time you’re the most contagious, but you don’t even know you’re sick …?
This is readily explained as an evolutionary adaption in the cold viruses.
People tend to avoid people that are visibly sick – sneezing & coughing. So colds that are ‘secretly’ contagious during the first few days, while the patients are not yet showing symptoms, are more likely to spread and reproduce. Thus those types of colds tended to survive, while the ones that were most contagious while the symptoms are most visible tended to die out.