Unveiling the Mpox Immunity Gap: Key Findings from Australian University Research

A groundbreaking study led by researchers from the University of New South Wales' Kirby Institute and the National Centre for Immunisation Research and Surveillance, affiliated with the University of Sydney, has highlighted a significant immunity gap against mpox in Australia's at-risk populations. Published recently in eClinicalMedicine, the research reveals that two-dose vaccination coverage among gay, bisexual, and other men who have sex with men stands at a mere 9.6% to 15%. This low level falls well short of the threshold needed for herd immunity, leaving communities vulnerable to potential outbreaks.

The study, drawing from national surveillance data and cohort analysis between 2022 and 2024, underscores how Australia's relatively low prior transmission rates have resulted in limited natural immunity. Unlike countries like the United States or United Kingdom, which saw peak cases in 2022, Australia experienced a small outbreak that year followed by a larger one in 2024, totaling over 1,400 cases. With transmission now subdued, experts argue this presents a critical window to bolster defenses.

Understanding Mpox and Its Transmission Dynamics in Australia

Mpox, caused by the monkeypox virus from the Orthopoxvirus genus related to smallpox, spreads primarily through close physical contact, including sexual transmission, respiratory droplets, or contaminated materials. In Australia, nearly all cases since 2022 have occurred among gay, bisexual, and other men who have sex with men, prompting targeted vaccination campaigns starting in August 2022 using the JYNNEOS vaccine, administered in two doses four weeks apart.

While the virus typically causes mild symptoms like rash, fever, and swollen lymph nodes, severe outcomes can affect immunocompromised individuals, children, or pregnant people. Australia's outbreaks have been contained without widespread community spread, but the resurgence in 2024 signals ongoing risks, especially with global clade Ib variants raising concerns.

The At-Risk Population: Gay, Bisexual, and Other Men Who Have Sex with Men

Gay, bisexual, and other men who have sex with men represent the core group affected, with multiple sexual partners increasing exposure risk. The study notes that community surveys often overestimate coverage at 40-70% because they sample highly engaged individuals via sexual health services or LGBTQ+ networks. Broader estimates reveal a stark gap, particularly among less connected subgroups like bisexual men or those born overseas.

This disparity highlights equity issues: those outside mainstream GBQ+ networks may miss risk messaging and free vaccination access. Universities like UNSW play a pivotal role here, with the Kirby Institute's long-standing expertise in HIV and STI research informing targeted interventions.

Methodology: How Researchers Assessed Immunity Levels

Leveraging prospective cohort data from the TraX study at UNSW's Kirby Institute, researchers tracked vaccination behaviors from 2022-2024. They combined this with national notifications and modeled coverage using conservative assumptions. Mixed-methods analysis identified drivers like trust in health authorities and barriers such as access logistics or misinformation.

Key metrics included first-dose uptake (high in cohorts), second-dose completion (strong), but population-wide extrapolations showed insufficient protection. This rigorous approach, blending quantitative surveillance with qualitative insights, exemplifies Australian higher education's contribution to evidence-based public health.

Critical Statistics: Vaccination Coverage and Outbreak Patterns

Two-dose coverage: 9.6%-15% among GBMSM.
First outbreak (2022): Small scale.
Second (2024): Over 1,400 cases nationally, mostly NSW-acquired.
Hospitalizations: 26 in recent NSW data.
Global comparison: Australia's delayed peaks contrast with early 2022 surges elsewhere.

Drivers and Barriers to Vaccine Uptake

• Drivers: Public health messaging, community trust, free access at clinics.
• Barriers: Logistical hurdles (e.g., second-dose timing), low perceived risk post-2022, engagement gaps in non-GBQ+ identifying MSM.

Qualitative data showed decisions aligned with official advice, but broader reach is needed via general practices.

Implications for Public Health and Outbreak Prevention

The immunity gap explains the 2024 resurgence despite global declines. Without action, imported cases could spark chains. Universities are central: Kirby Institute's TraX monitors real-world effectiveness, while NCIRS models scenarios. This research urges integrating mpox shots into routine care, potentially averting emergencies like clade Ib threats.

Read the full eClinicalMedicine study for detailed modeling.

The Role of Australian Universities in Infectious Disease Research

UNSW Sydney's Kirby Institute, world-renowned for HIV breakthroughs, exemplifies higher education's impact. Collaborations with USyd-linked NCIRS amplify surveillance. Such studies inform policy, from vaccine rollouts to equity-focused campaigns. Amid funding pressures, this underscores universities' societal value in health security.

Expert Perspectives: Quotes from Lead Researchers

Associate Professor Frank Beard: "These findings suggest a major immunity gap within the broader at-risk population in Australia."

Scientia Professor Andrew Grulich: "Mpox vaccination should be offered opportunistically to all sexually active gay and bisexual men and other men who have sex with men wherever they receive care."

These voices from UNSW and affiliates call for sustained monitoring.

Recommendations: Bridging the Gap Through Policy and Practice

• Opportunistic vaccination at GPs and sexual health clinics.
• Trusted community messaging to boost awareness.
• National monitoring of epidemiology and coverage.
• Targeted outreach to underserved subgroups.

NCIRS summary and expert commentary.

Future Outlook: Strengthening Australia's Defenses

With low current transmission, now is ideal for action. Universities like UNSW continue TraX for boosters and variants. Potential clade Ib risks globally demand vigilance. Enhanced coverage could prevent pandemics, showcasing higher ed's proactive role.

Broader Impacts on Higher Education and Public Health Careers

This research highlights opportunities in epidemiology, vaccinology at Australian unis. Demand grows for experts in outbreak modeling, equity studies. Programs at UNSW, USyd prepare next-gen leaders.

Photo by Andy Wang on Unsplash