In response to rising concerns about the possibility of polio returning, UK health officials will give children living in London under 10 years old an extra dose of polio vaccine.
Although no one has been tested for the poliovirus that causes paralysis, it was found in a number of London sewage samples. This suggests “there is some level of virus transmission” in parts of London that “has gone beyond a close network of a few individuals,” the UK Health Security Agency said in a statement.
The UK’s vaccine expert advisory committee recommended offering the extra polio booster to kids after considering London’s polio vaccination coverage, which is lagging behind World Health Organization targets.
Learn More Polio’s Arrival in the U.S. Is Another Urgent Reminder That Kids Need to Get Vaccinated
Of the 116 polio viruses isolated from London sewage samples in recent months, the vast majority are relatively harmless versions classified as “vaccine-like” virus. People can spread this version through their feces after receiving a live-attenuated oral version of polio vaccine that’s no longer offered in the UK.
This virus can sometimes cause paralysis if it undergoes sufficient mutations. On several occasions in London since February, this more dangerous strain, known as “vaccine-derived” polio virus, has been detected in sewage samples.
Normal surveillance would not detect any trace of the vaccine-like viruses within a year. However, the constant detections in the past months warrant further intervention by health officials.
Officials said that the booster program’s goal is to improve protection in London from poliomyelitis and reduce transmission. According to the UKHSA, paralytic Polioma is considered low at the national level because many people are immune through vaccination. Authorities are expanding surveillance of sewage in London and other parts of the country, to see if there is any spread.
It is possible to transmit the virus from one person to another without showing any symptoms. However, many people will develop a flu-like illness, with fever, headaches, and sore throats. Although these symptoms usually disappear, the virus may cause paralysis in certain cases. If the virus attacks breathing muscles, it can cause paralysis and even death.
Learn More Why It’s So Hard to Get a Monkeypox Vaccine Right Now
The UK’s last case of wild polio was in 1984 and the country was declared polio-free in 2003.
In July the US announced its first case of polio in almost a decade. It was reported by a 20-year old man from New York State who had not been vaccinated. A second case of polio was reported by Israel in March. This time, a girl unvaccinated suffered paralysis. The results were positive.
The UK health authorities said they are working with peers in the US, Israel and the WHO to probe links between what’s detected in London and the cases reported in those two countries.
Read More From Time