Cases of vaccine-associated polio are being reported in the media. I thought polio was almost eradicated with only a few cases being reported annually in Pakistan.
What is vaccine-associated paralytic polio (VAPP)?
Vaccine-associated polio viruses come from mutated forms of oral poliovirus (OPV). These viral strains can cause paralytic polio in the same way as the previous wild virus. This form of polio has become a challenge to the polio eradication program. Increasing numbers have been reported in the last few years. There were 1,000 cases in 2020.
In recent times (2024), cases have been reported in Guinea, Democratic Republic of Congo, Algeria, Benin, Burundi, Cameroon, Central Africa Republic, Chad, Congo, Eritrea, Ethiopia, Ghana, Kenya, Malawi, Mozambique, Niger, Nigeria, Tanzania, Togo and Banda Aceh (Indonesia).
There are many reasons for the resurgence in cases attributed to this form of polio. It is primarily due to low immunization rates in the target population. This is due to many factors including vaccine shortages, distribution problems as happened during the COVID-19 pandemic, civil disturbances, and funding shortfalls. It has global implications.
How is vaccine-associated paralytic polio (VAPP) transmitted?
VAPP is transmitted the same way as wild polio. The virus is transmitted from person to person through contact with faecal material or when a person coughs or sneezes (droplet infection).
It can also be transmitted by untreated sewage in places where public health infrastructure is lacking. This is an issue in many low-income countries. Infected people with poor hand hygiene may pass it on through contaminated food.
Who is at risk of getting VAPP.
Anyone who is unvaccinated for polio can get VAPP. It may also be a risk for those who are not current for the vaccination.
There is no transmission of polio in Australia. We have high rates of polio immunization and we do not currently use a live form (OPV) for vaccination against the disease. The use of oral polio vaccine (OPV) ceased in Australia in 2005. It was replaced with IPV (inactivated polio vaccine). It is impossible for this type of vaccine to infect another person with the disease. Prior to the change, it was common practice to update mothers with a polio booster at the same time as vaccinating their child with OPV. Australia made the change to IPV when it was determined the risk of VAPP was higher than the risk of getting the wild polio disease.
Polio vaccine is provided free to all children, eligible, under the National Immunisation Program in the first year of life. It is now included in a combination vaccine (Infanrix hexa, Vaxelis) and given at 2, 4 and 6 months with a booster at 4 years.
How is VAPP prevented?
Polio vaccination protects you against the disease, whether it is caused by the wild virus or VAPP. Travellers may be at risk if visiting countries with circulating paralytic polio virus.
A booster is recommended if they have been previously fully vaccinated, and it is more than 10 years since their lost dose.
Travellers should strictly adhere to the rules of “eating and drinking safely” when travelling in a low-income country.
Polio is a notifiable disease in Australia.
Did you know?
Vaccine associated paralytic polio strains were detected in London sewage in 2022. No associated cases of polio occurred. The risk of transmission was considered very low given the high vaccine coverage (> 86%). At risk communities were targeted to check their vaccination status. The last case of polio in the UK was reported in 1984.
Australia was declared polio-free in 2000. Only one case has been reported since 1987.
PNG experienced an outbreak of VAPP in 2018. Twenty-six cases were reported across 9 provinces. Factors attributed to the outbreak included low population vaccination rates and poor surveillance systems. This has since been addressed.
Actress Mia Farrow contracted polio in 1954 at the age of 9 years. She needed to use an iron lung. More than 500 people were affected in the outbreak. She was appointed a UNICEF goodwill ambassador in 2000 for her work on polio vaccination programs around the world.
Johnny Weismuller also contracted polio and was recommended swimming for rehabilitation. He went on to win 5 Olympic gold medals in swimming. He was the most famous Tarzan.
