Hmm, the study didn't hand out hugs, but merely correlated people who'd happened to have received them. The study authors already note that "Individuals who report perceiving the availability of a network of supportive individuals tend to show better adaptation when faced with stress." People with a support network are doubtless more likely to be hugged. Therefore it's not clear to me that the hugs contribute anything, or that any attempt was made to control for this - a classic case of "study measures correlation, headline reports causality".