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Subcutaneous and intradermal administration of mpox vaccine well tolerated, AusVaxSafety study finds

New research published by AusVaxSafety has shown that the intradermal administration route – a dose-sparing strategy – of the JYNNEOS (modified vaccinia Ankara-Bavarian Nordic, MVA-BN) mpox vaccine had a similar side effect profile to that reported following subcutaneous (recommended route) vaccination.

Researchers analysed AusVaxSafety vaccine safety survey data from 13,306 JYNNEOS vaccine recipients, of which 5,643 had subcutaneous and 7,663 had intradermal vaccination.

The side effect rates were similar between administration routes but highest following dose 1 for both routes (intradermal: 53% after dose 1 vs 35% after dose 2; subcutaneous: 47% after dose 1 vs 31% after dose 2).

The most common side effects were local redness, itching and swelling (following intradermal vaccination) and local pain, swelling and redness (following subcutaneous vaccination).

Dr Laura Lopez, study author and researcher at AusVaxSafety, said the study found a low percentage of people reporting either the need for medical review or missing daily activities following vaccination, suggesting the vaccine is generally well tolerated.

“The rates of individuals seeking medical review were low overall across doses and administration routes [0.7–1.2%]. 

“Most people reported needing only phone advice or a primary health care review, and only a small percentage of individuals reported missing work, study or other daily activities due to their side effect/s, irrespective of dose or administration route [2.5–3.7%],” Dr Lopez said.

In response to a global shortage of JYNNEOS vaccine, Australia adopted a dose-sparing schedule for the recent mpox outbreak, with 0.1-mL intradermal JYNNEOS vaccine recommended for pre-exposure and 0.5-mL subcutaneous vaccine for post-exposure prophylaxis, forming a primary vaccination course of two doses given four weeks apart.

Professor Nick Wood, senior author and Associate Director of Clinical Services and Vaccine Safety at the National Centre for Immunisation Research and Surveillance, said the study would not have been possible without the flexibility and reliability of the national AusVaxSafety surveillance system.

“The adaptability of the AusVaxSafety system allowed for the rapid establishment of tailored vaccine safety surveillance specific to the needs of the mpox vaccination program, ensuring the timely capture of data from more than 80% of mpox vaccination clinics across Australia,” said Professor Wood.

“This builds on the success of COVID-19 vaccine surveillance and highlights the ability of the system to pivot to new vaccines or vaccines used in outbreak settings, to ensure at-risk populations can get vaccinated safely.”

Access the full study here

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