Australia Lifts Age Restriction on Mpox Vaccine, Does Not Recommend Booster

A family nurse practitioner prepares a syringe with the Mpox vaccine for inoculating a patient at a vaccination site in the Brooklyn borough of New York, on Aug. 30, 2022. Jeenah Moon/AP Photo

Australia’s vaccine advisory group has removed the age restriction of 18 years and over for the mpox (monkeypox) vaccine.

The Australian Technical Advisory Group on Immunisation (ATAGI) recently reviewed vaccine guidance in response to an “upsurge of mpox cases in Australia.”

National Communicable Disease Surveillance data shows Australia had detected 385 cases of Mpox in 2024 as of Sept. 2.

ATAGI said published studies indicate the JYNNEOS mpox vaccine is “moderately to highly effective” at reducing the severity of symptoms.

“The ATAGI recommendations for mpox vaccination have been updated to remove the age restriction; people of all ages who are at risk of exposure to mpox are recommended to receive the mpox vaccination,” the advisory (pdf) states.

“ATAGI will monitor the evolving mpox epidemiology in Australia and other affected regions. Vaccine recommendations will continue to be reviewed and updated if required.”

Booster Not Recommend

However, in its latest advisory, ATAGI said it does not recommend booster doses of the mpox vaccine for those who are fully vaccinated. A fully vaccinated individual is someone who has taken two doses of the vaccine at least 28 days apart.

Rather, the government agency recommended two doses of a mpox vaccine.

“People recommended to receive the mpox vaccine and who received the first dose 28 days ago should receive their second dose as soon as possible to maximise protection,” ATAGI said.

ATAGI noted the first case of mpox was discovered in Australia in May 2022, hitting a peak in Aug. 22 before declining.

“In 2024, there has been a resurgence of clade II cases in Australia. Most cases have been acquired in Australia and a small number have been in people who were fully vaccinated,” ATAGI said.

Mpox signs and symptoms include a distinctive rash, bumps that turn into sores and blisters, swollen lymph nodes, fever, headache, muscle aches, joint pain, back pain, chills, and exhaustion.

“The rash changes and goes through different stages, before forming a scab and falling off,” the Australian health department states.

“The rash may occur on any part of the body, including the face and inside the mouth, the torso, arms and hands, legs and feet, and the genital and perianal regions.”

Currently in Australia, the mpox cases detected are Clade IIb of virus, distinct from the Clade Ib outbreak in Africa.

What are the Vaccines?

Monash University Molecular Virologist Associate Professor Vinod Balasubramaniam said JYNNEOS, also known as Imvamune or Imvanex, is a live, non-replicating smallpox and mpox vaccine developed by Bavarian Nordic.

The second vaccine, ACAM2000, is a live vaccinia virus vaccine developed by Sanofi Pasteur.

“Both vaccines have been shown to be effective against the current circulating strains of mpox, particularly the West African clade. However, it is important to note that the vaccines may have reduced efficacy against the more virulent Central African clade,” he said on Aug. 15.

The Australian health department states JYNNEOS is the preferred vaccine for use in Australia, due to its “safety profile” and being simpler to administer.

Additionally, ACAM2000 is not suitable for those who are immunocompromised, pregnant or breastfeeding, have cardiac disease or cardiac risk factors or active eczema.

However, JYNNEOS is in limited supply globally and high international demand, according to the Australian government.

For this reason, access to the vaccine is being prioritised for high risk population groups, close physical contacts of infected cases, and high-risk occupations.

Vaccine Effectiveness

UNSW Sydney Professor Andrew Grulich said the currently available vaccines were highly, but not completely, effective in preventing mpox.

“We saw in 2022 that rapid roll-out of these vaccines was associated with rapid declines in transmission. In Australia, vaccine roll-out in gay and bisexual men averted a serious epidemic associated with the global gathering of LGBTQI+ people at the Sydney World Pride festival in early 2023,” he said.

“In 2024 numbers have rebounded, indicating that current vaccination levels are too low. Importantly, the strain that has led to a public health emergency in Africa has not been detected in Australia yet.”

Australian National University poxvirus researcher Professor David Tscharke described mpox as a “slow-burning fire” that has been able to smoulder in Central Africa and is flaring up again.

“This time, the WHO is ringing the alarm,” he said. 

Tscharke said vaccine supplies are “not getting to the places they are needed,” despite the disease being one that “can be stopped” by an existing vaccine.

“It is hoped that the WHO call to action by issuing their notice of concern will turn this around so that the spread of this disease can be stopped,” he said

The World Health Organisation (WHO) declared mpox as a public health emergency of international concern on Aug. 14.