Other
Herd immunity, generated from previous exposure to cold viruses, plays an important role in limiting viral spread, as seen with younger populations that have greater rates of respiratory infections.[33] Poor immune function is also a risk factor for disease.[33][34] Insufficient sleep and malnutrition have been associated with a greater risk of developing infection following rhinovirus exposure; this is believed to be due to their effects on immune function.[35][36] Breast feeding decreases the risk of acute otitis media and lower respiratory tract infections among other diseases[37] and it is recommended that breast feeding be continued when an infant has a cold.[38] In the developed world breast feeding may not however be protective against the common cold in and of itself.[39]