Can you get two colds at once?

Published 12:00 am Friday, April 13, 2018

A: Yes, you can. The phenomenon is known medically as coinfection and occurs when two germs, in this case viruses, cause infections at the same time.

More than 100 viruses can cause the common cold, so it’s not unusual to be exposed to two at once. And, since one virus doesn’t typically confer immunity against the other, it’s not unusual to be infected by two viruses at once.

The best data about coinfection come from studies of more serious viruses, such as HIV and hepatitis. These studies show that coinfection can worsen, ameliorate or have no impact on the course of an illness. The outcome depends on the viruses involved.

With HIV, coinfection with the two main types, HIV-1 and HIV-2, is actually beneficial. It slows the progression of the disease. Coinfection with HIV and hepatitis C virus, on the other hand, worsens the outcome.

With influenza viruses, which cause respiratory infections similar to that of the common cold, coinfection is uncommon.

Coinfection with influenza A and B, two major types of flu virus, occurs in fewer than 2 percent of cases but doesn’t seem to affect the overall outcome.

Coinfection with the common cold has proved difficult to study in the past because of the large number of viruses that can cause a cold. In the past few years, however, advances in molecular genetics have afforded scientists insights into the rhinovirus, the most common cause of the common cold.

In 2009, scientists were able to sequence all of the genetic material from the 99 known strains of rhinovirus. They found that coinfection with multiple strains is a common occurrence. They also found that coinfection provided viruses an opportunity to mutate into new strains.

Diagnostic tests for many of the viruses that cause colds have now become commercially available. In 2013, doctors used these tests to study 225 children in day care.

Almost half were infected with more than one virus when they got sick. Children infected with multiple viruses did not appear to be sicker than those infected with a single virus, but they stayed sick longer. These findings were recently confirmed by a systematic review of all published studies.

So while you can get two colds at once, you probably won’t feel any worse than you would with one. The difference that you might experience is being sick for longer than you might otherwise expect.

Marketplace