A New Zealand expert says the detection of viruses derived from the oral polio vaccine in London and New York's wastewater serve as a "wake-up call" around childhood immunisation rates.
"It's sort of a wake-up call to make sure we're giving attention to keeping our vaccination rates as high as possible," University of Otago professor Peter McIntyre told Breakfast.
His comments come after health authorities in the UK reported finding evidence the virus, derived from the oral polio vaccine, has spread in London.
Professor Peter McIntyre says the detection of viruses derived from the oral vaccine highlights the need for children to get immunised. (Source: Breakfast)
No cases of the paralytic disease have been found in people, but London children aged one to nine have been made eligible for booster doses from an injected polio vaccine.
READ MORE: Polio in NYC's wastewater points to virus circulating
Poliovirus has also been found in New York's wastewater and one person recently suffered paralysis from an infection.
McIntyre, a paediatrician specialising in infectious diseases, said it appeared a "rogue vaccine virus" is circulating.
The oral vaccine contains weakened live poliovirus, so there is a risk, described as rare, of vaccine-derived poliovirus infection. The live virus in the oral vaccine can mutate into new forms potent enough to trigger new outbreaks.
According to the Ministry of Health, the weakened virus can cause polio in about one in 750,000 cases.
New Zealand switched to using the inactivated polio vaccine (IPV) in 2002. Most other developed countries also use the IPV, but many developing countries still use the oral vaccine.
"It doesn't matter even if a rogue vaccine virus is circulating, as long as your immunity is OK," McIntyre, also an epidemiologist, told Breakfast.
Polio has disappeared from New Zealand and has mostly been wiped out from other developed countries. However, outbreaks remain in Pakistan, Afghanistan and parts of Africa.
There is an outbreak of circulating vaccine-derived poliovirus type 3 in Israel.
Initial symptoms of polio include fever, fatigue, headache, vomiting, and muscle stiffness. Among people paralysed by the disease - one in 200 infections - death can occur in up to 10% of cases when their breathing muscles become immobilised, the World Health Organization says.
The disease mostly affects children under five. Given there is no cure for polio, immunisation is responsible for protecting people against the disease.
READ MORE: London kids offered polio booster after more virus found
In New Zealand, babies can be immunised against polio as part of their free childhood immunisations at six weeks, three months and five months old. Children aren't considered protected until they've had all three doses.
Booster doses are given when they're four years old.
McIntyre said childhood immunisation rates in New Zealand had recently slipped, singling out coverage at six months.
Data shows immunisation coverage at six months as at June (three-month reporting period) is 67.2%. In early 2020 - before the Covid-19 pandemic - it was 79.2%.
"It's not mayday yet by any means but I think this is just another reminder about how important it is to keep those rates high and to get them [vaccinations] at the right time," McIntyre said.
"As long as the disease exists somewhere it can potentially come back here unless we make sure our vaccination rates are as high as they can possibly be."
SHARE ME