The recent detection of the vaccine-derived poliovirus type 2 case in New York, USA, and isolates in several environmental samples collected in London are stark reminders that as long as polio exists anywhere, it is a threat everywhere. It also highlights the importance of vaccination as the only form of protection against polio and other vaccine-preventable diseases and the work that needs to be done in our communities to encourage the uptake of vaccines. Also, as the world gets closer to zero wild poliovirus cases, it is increasingly important to track all forms of the virus wherever they may appear, including in polio-free regions.