Hugging can make you less likely to catch a virus cold.

Daily social stress is known to correlate with susceptibility to cold virus infection. Cohen et al. ask whether social support and the actual receipt of physical touch during daily life—being hugged—attenuate the association of interpersonal stressors (social conflict) with subsequent risk for infection, cold signs, and clinical disease in response to an experimentally administered cold virus. They find, not surprisingly, that the answer is yes, consistent with numerous studies that have shown that social support boosts immune function. Here is their abstract:

Perceived social support has been hypothesized to protect against the pathogenic effects of stress. How such protection might be conferred, however, is not well understood. Using a sample of 404 healthy adults, we examined the roles of perceived social support and received hugs in buffering against interpersonal stress-induced susceptibility to infectious disease. Perceived support was assessed by questionnaire, and daily interpersonal conflict and receipt of hugs were assessed by telephone interviews on 14 consecutive evenings. Subsequently, participants were exposed to a virus that causes a common cold and were monitored in quarantine to assess infection and illness signs. Perceived support protected against the rise in infection risk associated with increasing frequency of conflict. A similar stress-buffering effect emerged for hugging, which explained 32% of the attenuating effect of support. Among infected participants, greater perceived support and more-frequent hugs each predicted less-severe illness signs. These data suggest that hugging may effectively convey social support.