Physicians in Israel recently reported that six women with autoimmune disorders developed the painful rash known as shingles 3 to 14 days after they received a first or second dose of Pfizer’s COVID-19 vaccine.
Yikes! Traditional and social media — not to mention vaccine foes — have pounced on the small study, warning that COVID-19 vaccines might reactivate the childhood chickenpox virus, triggering a shingles outbreak in adults.
But that’s like concluding that because the rooster crows at dawn every day, he makes the sun come up.
“It’s called a logical fallacy,” said William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center in Nashville, and also a liaison to the CDC’s immunization advisory committee, which makes vaccine recommendations that shape insurance coverage. “The Israeli doctors fell into this trap because the COVID-19 vaccination and the shingles outbreaks were related in time.”
Even the Israelis, who published in the journal Rheumatology, acknowledge that “the study design is not structured to determine a causal relationship.”
So let’s dig into what has been determined.
A sneaky virus called herpes zoster
Chickenpox is now preventable with a vaccine, but people born before 1995 probably had the childhood infection, which shows up as itchy red blisters. The virus, called varicella zoster, is part of the herpesvirus family, which includes the genital herpes virus that causes sexually transmitted infections.
After the chickenpox go away, the virus hides out in nerves, ready for a potential reappearance years or decades later as shingles.
Shingles is so common that you have a 1 in 3 chance of developing it by age 80 — unless you get Shingrix, the 4-year-old GlaxoSmithKline vaccine that is 90% effective at preventing it.