London children offered polio booster vaccine as more virus detected

Driving the news: The U.K. Health Security Agency said it had discovered a positive sample of the poliovirus in eight boroughs throughout London suggesting a level of spread. No specific cases were identified.

• UKHSA said Wednesday that all children in London 1-9 years old should get a polio vaccine booster dose now to stay protected.
• "This will ensure a high level of protection from paralysis and help reduce further spread of the virus," UKHSA said.

Be smart: The risk for paralytic polio across the U.K. remains low due to high vaccination numbers, the UKHSA said.

State of play: The levels of spread in London are a hint "that there is some level of virus transmission in these boroughs which may extend to the adjacent areas," UKSHA said.

• "This suggests that transmission has gone beyond a close network of a few individuals."

Flashback: U.K. health officials discovered polio samples in sewage for the first time in nearly 20 years back at the end of June, Axios previously reported.

• Officials said this meant there was likely a spread of a "vaccine-derived" polio virus between close contacts in London.
• In rare cases, the live polio virus in an oral vaccine can mutate and cause a new outbreak, AP reported at the time.

Meanwhile, New York health officials confirmed the first case of polio in the United States in almost a decade. Officials urged New Yorkers to get vaccinated.

Go deeper ... First U.S. case of polio in decades discovered in New York

• Back-to-school, back to outbreaks