On 28 July Australia’s chief medical officer Paul Kelly declared monkeypox a “communicable disease incident of national significance”. This means disease spread is serious enough that national policy, interventions and public messaging is needed to combat it, along with more resources.
It follows the World Health Organization declaring the spread of monkeypox a global health emergency earlier in July.
The US Centers for Disease Control and Prevention said there have been 20,311 monkeypox cases in 71 countries, including Australia, that have not seen monkeypox spread before. Here’s what we know about the vaccines and who should get vaccinated in Australia.
What vaccines are available for monkeypox?
On 4 August, the Australian government announced it had bought 450,000 doses of the third-generation Bavarian-Nordic vaccine, the first 22,000 of which were due to arrive within two weeks. That vaccine would be prioritised for at-risk groups including men who have sex with men – especially those travelling to countries with a significant outbreak – sex workers, and immunisation providers who are administering the ACAM2000 smallpox vaccine.
The ACAM2000 smallpox vaccine is also registered for use in Australiaand protects against monkeypox, but as it uses a weakened live pox virus it is not suitable for immunocompromised people. Supply of this vaccine is available to states and territories through the national medical stockpile. It hasn’t been widely used, since smallpox has been eradicated.
With more than 70 countries now affected by monkeypox outbreaks, this newer vaccine is in short supply globally.
How do the vaccines work?
The older ACAM2000 vaccine is made from a virus called vaccinia, which is a type of pox virus related to smallpox and monkeypox, but which does not cause either disease, and which is also much milder than both viruses.
Administering the vaccine requires special training.
The skin is repeatedly scratched with a needle dipped into the vaccine. The virus begins to grow at the injection site, causing a red, itchy sore spot, or a “pock” in the days afterwards. It then eventually blisters and scabs over, and may leave a small scar.
The vaccine stimulates the immune system to develop antibodies that can then help the body recognise and then fight an infection if exposure to monkeypox occurs.
There is a risk that the vaccinia virus can be transmitted from the wound site to their close contacts. Those who are severely immunocompromised, who are pregnant, or who have eczema are most at risk, and can suffer serious adverse events either from being vaccinated or exposed to someone who has been. The risk of transmission from a vaccinated person to other people can be reduced by covering the injection site and good hygiene. The site is only infectious until scabbed over.
The newer vaccine, known as Jynneos in Australia, does not carry the same risk and can be used in immunocompromised people and is also safe for pregnant women, children, and those with skin conditions. It is administered more easily, given in two doses four weeks apart, though people already vaccinated against smallpox in the past may only need one dose. It has fewer side effects than ACAM2000, and doesn’t require the same aftercare precautions.
On 28 July Kelly announced the Australian Technical Advisory Group on Immunisation (Atagi) had made recommendations around how this newer vaccine should be used so that health workers are ready to administer it once supply is available in Australia. Kelly did not say when he expects the vaccine to be widely available, and Atagi advice states only that “limited supplies … have been secured by the Commonwealth and some states and territories,” though it is unclear if it has arrived in Australia yet.
Not everyone needs vaccination
Most healthy people recover from monkeypox within a few weeks, experiencing symptoms such as fever, headache, muscle aches, backache, swollen lymph nodes, chills and exhaustion. In some cases, monkeypox may begin with a rash or sores in the mouth and on the face, which may then spread to other parts of the body.
Severe illness and death is a risk in rare cases, particularly in immunocompromised people.
ACAM2000 does protect against monkeypox. But according to Atagi, Jynneos is the preferred vaccine for these vulnerable groups, and it is also the preferred vaccine for use in people exposed to the virus and at risk of developing disease. Vaccination after exposure can prevent disease developing, known as post-exposure prophylaxis.
Atagi advice states that “For healthy non-pregnant adults, where Jynneos is not suitable or not available, ACAM2000 has an established profile and may be considered” for those exposed to the virus or at high risk of exposure.
The good news is monkeypox does not spread easily between people. You need close contact with the lesions, body fluids, or respiratory droplets through extended face-to-face contact with an infected person to be at risk.
With a low number of cases in Australia, contact tracing is straightforward and infection risk is lower, but high-risk communities especially are on alert. Until at least the end of November, monkeypox is a notifiable disease in Australia, which means health authorities must be told of every case.
Who should get the vaccine?
In Atagi advice updated late July, the key risk groups recommended for vaccination include anyone who is a high risk monkeypox close contact within the past 14 days. High risk groups include gay, bisexual and other men who have sex with men who have a high number of sexual contacts are at the highest risk of monkeypox infection.
Those living with HIV, a recent history of multiple sexual partners, participating in group sex, or attending sex on premises venues may also be considered for vaccination, the advice states. Those taking HIV prevention medication due to having a number of sexual partners may also be recommended for vaccination.
Atagi states that sex workers, particularly those whose clients are in high-risk categories, and anyone in risk category planning travel to a country experiencing a significant outbreak, should also have vaccination recommended to them between four-to-six weeks prior to departure.
Healthcare workers who will be administering ACAM200 can be offered either vaccine if they have not previously received a smallpox vaccine. Healthcare workers who will only be administering the Jynneos vaccine and otherwise have no anticipated occupational exposure to monkeypox are not routinely recommended for smallpox vaccination.
For those health workers who have already received a smallpox vaccine in the past, a booster dose is recommended if the previous dose of a smallpox vaccine was given more than ten years prior.
Vaccination is also being offered on a case-by-case basis to high-risk close contacts of monkeypox cases, such as household contacts and health workers.
“Vaccination within four days of first exposure to an infectious case will provide the highest likelihood of prevention of disease,” Atagi says.
I received a smallpox vaccination as a child. Am I still protected against monkeypox?
A systematic review published in 2019 suggests that protection offered against smallpox virus may last more than 20 years after vaccination. A separate small study found protection may last 35 years or longer. It is hoped protection against monkeypox would last similarly.
According to Atagi: “Childhood smallpox vaccination may confer a longer lasting immune response than vaccination during adulthood, however this is uncertain. Those who have previously received a smallpox vaccine are likely to have some residual protection.”
