Summertime colds tend to last longer and pack more of a punch than the winter variety, although they occur only about 25% as often, Angela Chen writes in the Wall Street Journal.
"A winter cold is nasty, brutish, and short," says Bruce Hirsch, an infectious-disease specialist at North Shore University Hospital, while summer colds—which strike between June and October—"tend to linger" and can "go on for weeks and reoccur," which leads many people to mistake them for allergies. Experts say summer colds can bring more severe, flu-like symptoms, like fever, diarrhea, and aches, in addition to sneezing and coughing.
Experts attribute the differences in severity to the fact that summer colds and winter colds are caused by different viruses: While both are spread by direct contact with sick people and germy surfaces, summer colds are caused by a contagion called the enterovirus, while a different virus called the rhinovirus—which causes the common cold—is responsible for winter sickness. It is unclear why summer colds tend to be caused by enterovirus and not rhinovirus, as both are present all year, experts note.
Many people mistakenly try to "sweat out" a summer cold, which can prolong the illness, according to Roger Baxter of the Kaiser Permanente Vaccine Study Center. In addition, influenza expert Ronald Eccles says moving between warm outdoors and air-conditioned spaces might also make the body more vulnerable to sickness in the summer.
However, winter colds occur at a higher rate because colder weather and lack of sunlight decreases the body's immunity, he adds.
Regardless of the season, Hirsch notes that both viruses thrive where large groups of people gather, such as schools, public transportation, sports games, and airlines—"anywhere there's crowding, you're likely to pick up a cold," he says (Chen, Journal, 8/26).