The Australian Poliovirus Surveillance Program has detected a vaccine-derived poliovirus in pre-treated sewage from the Western Treatment Plant in Melbourne on 2 December 2024.
Victoria's Chief Health Officer, Dr Clare Looker, said the virus was detected in tiny concentrations as part of routine environmental surveillance in Victoria that supports the Global Polio Eradication Initiative.
"The poliovirus detection shows our routine testing is working and does not mean someone has polio. It is likely to have come from a person who received live vaccine in another country and has continued to excrete it since arriving in Victoria," Dr Looker said.
"Australia remains polio-free, and Victoria hasn't had a locally acquired case since the 1970s.
There is an extremely low risk that the detection of this poliovirus will cause disease in anyone."
"Australia has very high rates of immunisation across the population, and we have excellent sanitation infrastructure that prevents people being exposed to sewage," Dr Looker said.
Victorians have access to a free polio vaccine at two, four and six months of age and a booster dose at four years of age through the National Immunisation Program.
An inactivated polio vaccine is used in Australia, which means it cannot multiply in a person in the way the live vaccine does, and is not found in the bowel or sewage and cannot cause polio disease.
Polio immunisation coverage in Victoria is extremely high with 95 per cent of children at five years of age protected - above the national average. However, childhood immunisation coverage has declined since 2021 and some populations in Victoria have lower coverage.
In addition, eligible people less than of 20 years of age, and refugees and humanitarian entrants of all ages are eligible to receive free inactivated polio vaccine missed in childhood as part of catch-up arrangements through the National Immunisation Program.
Dr Looker said the high level of immunisation in children and adults makes any risk of polio occurring in Victoria extremely low.
"Due to this recent detection, increased testing of sewage samples from the Western Treatment Plant in Melbourne will continue over the next 6 months to monitor the situation.
"This is a reminder that immunisation provides the best protection from many infectious diseases, and I encourage everyone, especially parents of young children, to keep immunisations up to date," Dr Looker said.
