Risk of shingles rises after COVID-19 infection: study

Adults over 50 who have had COVID-19 are more likely to experience a shingles outbreak, according to new research.

A study published in the journal Open Forum Infectious Diseases last month looked at data from 400,000 people who had been infected with COVID-19 and 1.6 million who had not. It found adults over 50 who have had COVID-19 are 15 per cent more likely to develop shingles within six months. The risk grows to 21 per cent for those who have been hospitalized with COVID-19.

Shingles, also known as herpes zoster, is a viral infection characterized by painful blisters that usually appear on one side of the torso. An infection can take as long as five weeks to clear up.

Shingles is caused by the varicella zoster virus, the strain of herpes which causes chickenpox. After someone has had chickenpox, the virus can remain dormant in the body for decades before reactivating to cause shingles, explained Dr. Kashif Pirzada, a Toronto-based emergency physician.

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"It never fully leaves your body. Your immune system is keeping it in check like a tug-of-war," Pirzada told CTV’s Your Morning on Tuesday. "If you have a big shock to your immune system like a COVID infection, or if you're not sleeping, you're not eating well...then it could flare up and cause shingles."

In rare cases, the varicella zoster virus can also cause a neurological disorder known as Ramsay Hunt Syndrome. This is a form of facial paralysis that can occur when a shingles outbreak affects the facial nerve near one of the ears. Pirzada said its effects can be devastating. Earlier this month, a diagnosis of Ramsay Hunt Syndrome forced Justin Bieber to cancel a string of tour dates.

"It affects your balance, your hearing, your taste, the movements of your face, even closing your eyes," Pirzada. "And the recovery is long. If you start antivirals early, you can have a better course. But the recovery can take months, even a couple years."

Right now, Pirzada said, the best defence against shingles for people who have already had chicken pox is the shingles vaccine.

While the chicken pox vaccine has been available to children in Canada since the year 2000, the shingles vaccine is currently only recommended for adults over 50. Some provinces offer the vaccine at no cost to seniors, and advocates want to see the rest of the country follow suit.

The National Advisory Committee on Immunization is also considering recommending the vaccine for anyone 18 and older who is immunodeficient or immunocompromised.

As for claims circulating online that the COVID-19 vaccine causes shingles outbreaks, Pirzada said they're not true.

"You're going to win [Lotto] 649 a couple times before you get shingles from the vaccine," he said.