Adverse Reactions After Intradermal Vaccination With JYNNEOS for Mpox in Korea

Area of Science:

• Public Health
• Vaccinology
• Epidemiology

Background:

• Mpox outbreak in South Korea prompted a national vaccination campaign.
• JYNNEOS (Modified Vaccinia Ankara vaccine) was administered intradermally to high-risk individuals.
• Understanding adverse reactions is crucial for vaccine safety monitoring.

Purpose of the Study:

• To investigate adverse reactions following intradermal JYNNEOS vaccination.
• To assess the incidence and severity of local and systemic symptoms.
• To evaluate the overall tolerability of the intradermal JYNNEOS vaccine in a real-world setting.

Main Methods:

• Anonymous online survey conducted at the National Medical Center.
• Data collected from May 22 to July 31, 2023.
• 142 respondents reporting on their vaccination experience.

Main Results:

• Over 80% experienced mild local reactions like pruritus, redness, and swelling.
• Incidence of local reactions increased slightly after the second dose.
• Fatigue was the most common systemic symptom, reported by 37.7% after the first dose and 24.6% after the second.

Conclusions:

• Intradermal JYNNEOS vaccination for Mpox was generally well-tolerated.
• Local reactions were common but predominantly mild.
• The vaccine safety profile supports its continued use in public health initiatives.