Our case
A 54-year-old Thai female presented with multiple blisters on top of
erythematous rashes that started three days after receiving the first
dose of the Pfizer-BioNTech as the booster shot.
She received two doses of the Sinovac-CoronaVac COVID-19 vaccine four
months prior, with no side effects observed. Two months after
vaccination, she was hospitalized due to COVID- 19 pneumonia with no
cutaneous eruption noted.
Two months after the COVID-19 infection, she got the Pfizer-BioNTech
booster shot. A couple of days later, she developed mild itchy
erythematous rashes on her left upper arm. The rashes spread to her
upper chest, posterior aspect of the neck, and right arm the next day,
and some blisters developed on top of erythematous rashes on her left
upper arm. The blisters are located 7 cm distal to the vaccine injected
site. Three days after the blisters developed, she went to the hospital.
Dermatologic examination revealed erythematous macules and papules
coalesce into plaques on both arms, upper chest, and posterior aspect of
the neck. Multiple tense bullae were found on top of erythematous plaque
on the left arm (Fig. 1). The skin biopsy demonstrated a subepidermal
separation with predominated neutrophils. The direct immunofluorescence
had a negative result (Fig. 2).
She was diagnosed with a subepidermal blistering eruption related to the
Pfizer-BioNTech COVID-19 Vaccine. After three weeks of topical
corticosteroid and oral antihistamine were administered, her blisters
resolved. Only post-inflammatory hyperpigmented patches remained without
lesion recurrence (Fig.3).
Discussion :
Many cutaneous adverse reactions were reported after receiving an mRNA
vaccine. The typical reactions were delayed large local reaction,
swelling, erythema, urticarial, and flare of existing dermatologic
conditions. 2,3,4,5 Few bullous reactions from mRNA
vaccine were reported.6 Moreover, there were still
limited data about the cutaneous reactions from the booster vaccine in
this kind of combination regimen, especially in post-covid 19 infectious
patients.
Tomayko et al. 6. reported that 12 out of 733 patients
experienced subepidermal blistering eruption after mRNA vaccination. The
onset of bullae is usually seven days after vaccination. Our patient
seemed to develop blisters earlier than the median time in Tomayko’s
report, while the duration of the rash was similar at a median time of
three weeks.
Krammer et al.7 revealed that the previously infected
patients with only one vaccination dose usually have higher immunity
levels than the uninfected patients with two vaccinations. The result
corresponded with a higher rate of systemic adverse effects (headache,
fever, muscle pain) after vaccination in post-infectious patients.
However, there were no differences between the two groups in local
injected site reactions. Nevertheless, this study did not emphasize
cutaneous reactions other than local reactions.
It is possible that the blistering eruption in our patient was caused by
a high antibody response to the vaccination after the recent COVID-19
infection. Since the mRNA vaccines are novel medications, more
understanding is needed to prove this hypothesis.