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Blistering eruptions, including bullous pemphigoid, seen after COVID-19 vaccine


NEW YORK (Reuters) – SARS-CoV-2 mRNA vaccines may trigger subepidermal blistering eruptions, particularly bullous pemphigoid and most often in older adults, U.S. clinicians report.

However, “given the risks of SARS-CoV-2 infection, the rarity of these events, and the uncertainty of causality, clinicians should encourage full vaccination, including completion in those with blisters after the first dose,” they say in a letter in the Journal of Allergy and Clinical Immunology.

Mary M. Tomayko, MD, of Yale University, New Haven, Conn., and colleagues describe seven women and five men (median age, 83 years), with no history of bullous pemphigoid (BP) or autoimmunity, who developed inflammatory vesicles and bullae a median of 7 days (range, 12 hours to 21 days) after the first or second dose of a SARS-CoV-2 mRNA vaccine.

Dermatologists evaluated all 12 individuals and noted cutaneous bullae away from the injection site; skin biopsies revealed subepidermal separation and dermal infiltrates with eosinophils, they report.

One additional patient with a history of BP experienced a flare-up of BP 5 days after vaccination but did not undergo further testing.

The diagnosis of BP was confirmed in 8 of the 12 patients; the remaining 4 patients did not meet full criteria for BP diagnosis because immunologic testing was either not performed or was negative.

Of the five patients who developed blisters after the first vaccine, three tolerated the second dose, one with mild flaring, and the other two had the second dose withheld. Three patients diagnosed with dermatitis before vaccination had worsening dermatitis after the first shot and bullae after the second.

Blistering resolved or improved in 7 of the 12 patients over 2-8 weeks with combinations of topical corticosteroids, doxycycline, nicotinamide, and systemic corticosteroids. Five patients had ongoing disease at the time of submission of the manuscript.

“These observations raise the question of whether SARS-CoV-2 vaccines might play a role in BP initiation,” Dr. Tomayko and colleagues write.

“Certainly, the association could be coincident: The annual incidence of BP worldwide is estimated at between 2.4 and 21.7 new cases per million, so as large populations are vaccinated, some individuals will also develop BP,” they point out.

BP-like disease has also been observed after receipt of other vaccines, including the measles, varicella zoster, influenza, hepatitis B, and human papillomavirus vaccines.

“It is possible that some individuals who developed BP after SARS-CoV-2 immunization harbored subclinical BP or undiagnosed eczematous-variant BP that was unmasked by vaccination,” they add.

“It is conceivable that in those with more rapid development of bullae (e.g., after the first dose), transient bystander immune activation invigorated an existing subclinical autoreactivity. In those with more delayed kinetics, a new cutaneous response may have been primed. However, this is the first use of mRNA vaccines in humans, and a more complete understanding of any potential off-target immunostimulatory properties will require additional investigation,” the authors say.

For now, they say dermatologists and other clinicians should know that BP-like disease may develop after SARS-CoV-2 mRNA vaccination, particularly in older adults, with symptoms likely to rapidly improve with conservative treatment.

“Our experience suggests that the natural history of SARS-CoV-2 mRNA vaccine-associated BP-like disease may differ from that of conventional BP in some individuals, but further studies are required to confirm this hypothesis,” they add.

Reuters Health Information © 2021

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