People travelling overseas are not able to get all the vaccinations they need because of a global shortage of the hepatitis A vaccine.
A spokeswoman from the Department of Health and Ageing says pharmaceutical companies are working to address the shortage and priority is being given to travellers.
Lisa Maguire from pharmaceutical company GlaxoSmithKline says it is hard to say why there has been a bigger than usual uptake of the vaccine.
“It’s really hard to know why there can be peaks and troughs, but we can certainly make an assumption there’s been some increased travel and in turn there’ll be extra need for this vaccine,” she said.
“And what happens is there are a number of companies that supply the hepatitis A vaccine to the market. And if there’s a supply issue with any company, that will cause a shortage.”
Hepatitis A infects the liver, causing sickness for up to a month.