Polio Spread Detected In London Sewage For First Time In Decades

Topline

Several related samples of the virus that causes polio have been detected in the U.K. for the first time in decades, the U.K.’s Health Security Agency said Wednesday, leading British health officials to declare a national incident and urge the public to ensure they are vaccinated, though they caution the risk of contracting polio is low.

Polio vaccine vials seen at the vaccine distribution centre at Kasturba Hospital, during a national … [+] Pulse Polio Immunization program. (Photo by Pradeep Gaur/SOPA Images/LightRocket via Getty Images)

SOPA Images/LightRocket via Getty Images

Key Facts

The HSA said vaccine-derived poliovirus had been detected in wastewater from North and East London between February and June.

The virus most likely originated from a person who was vaccinated with a live form of the virus overseas, according to the HSA, as the live oral polio vaccine hasn’t been used in the U.K. since 2004 when it was replaced with an inactivated polio vaccine, which doesn’t carry the risk of transmission.

The HSA said small amounts of the poliovirus have been detected in sewage in recent years, but they have all been single detections that have been unrelated to each other.

The samples identified between February and June have been genetically related, indicating that there may have been some spread between closely-related individuals in London, according to the HSA.

No cases of polio, or its symptoms, have been reported in the U.K., and health officials said the risk of a vaccine-derived outbreak is rare.

The U.K’s last wild case of polio was in 1984, and the country was declared polio free in 2003.

Surprising Fact

Individuals who are vaccinated with the live virus can shed traces of the virus from their gut, which can then be spread through sewage—and be detected in the wastewater. In the U.S., the Centers for Disease Control and Prevention has also been monitoring Covid-19 levels through wastewater during the pandemic.

Key Background

Polio is a contagious virus that is spread mostly through contact with fecal material, and less commonly through coughs and sneezes, and in rare cases, can cause paralysis in those who are not vaccinated. While polio was widely eradicated in many countries around the world due to a successful global vaccination drive, vaccine-derived polio is on the rise. The live oral polio vaccine is still used in some parts of the world, which uses a weakened, but living form of the virus. Countries in Africa, the Middle East and parts of Asia, some of which had previously eradicated the disease, reported cases of vaccine-derived polio in the past year, and experts are working to update the live oral vaccine to reduce the risk of transmission.

Big Number

92%. That’s how many children reported completing the full series of a combination vaccine that protects against polio, among other diseases in the U.K. between 2020 and 2021, according to the National Institutes of Health. Regionally, about 87% of children in London reported receiving the vaccine, which is below the target rate of 95%.

Crucial Quote

Dr. David Elliman, a consultant pediatrician at Great Ormond Street Hospital, said in a statement anyone who is not immunized against polio, especially children, should get vaccinated. “Although we are an island, we are not isolated from the rest of the world, which means diseases could be brought in from abroad,” Elliman said. “The finding of vaccine-derived poliovirus in sewage proves the point.”