This does not happen with injected vaccines, which contain a form of the virus that is essentially dead and cannot replicate. That’s why many countries have switched to polio vaccination – the UK, for example, eliminated oral polio vaccination in 2004. The injected vaccine is distributed in four or five doses, the first dose when the baby is two months old.
How did it get here?
So why is there a virus in London’s sewage? The chain of transmission can start with a child – someone who was recently vaccinated with the oral vaccine in another country, Stonehouse said. “That child may be perfectly fine, and may have stopped producing vaccine-derived polio,” she said. “But they could have passed it on to someone else, who passed it on to someone else.” The virus appears to have spread through a small, but unknown, number in London.
I say London because that’s where the virus was discovered. Stonehouse says wastewater is periodically tested for multiple viruses at several sites there and one in Scotland. But many virologists think the virus could spread more widely in the UK and beyond — we just haven’t looked.
Why now? Stonehouse classed it as “unlucky”. Maybe this kind of spread has happened before and we didn’t notice. However, that is no reason to criticize. “The virus spreads so easily that any sign of transmission is really worrying,” she said.
How worried should we be? Adults can develop severe, but rare, disease, and they still need protection with any vaccines they received during childhood. I feel grateful for the vaccinated sugar cube that I was fed as a child.
Children under the age of 5 are at the highest risk of polio and its complications, so it is important to make sure children are vaccinated regularly. My daughter should be protected already – she has had the three recommended doses for a child her age.
Children are more likely to get and spread the polio virus than adults, and they can do so even if they have been vaccinated. A statement from the UK’s Joint Committee on Immunization and Immunization (JCVI) mentions unpublished evidence that pertussis vaccine given to pregnant women may reduce the child’s immune response compared to vaccinations, suggesting that those vaccines may not provide protection early in life. That’s part of the reason why even vaccinated kids like me are getting it. And because this vaccine is so safe, “even if you’re fully insured, you won’t be harmed by another shot,” Stonehouse said.
Polio cannot be cured, but it can be prevented. That’s why I packed my daughter with toddler-friendly cookies and a preloaded YouTube Video Cocolon on my phone, to our local doctor on a sunny Thursday afternoon.
My oldest daughter was not offered a booster dose — the vaccine was not given to children who had been vaccinated in preschool (at three years and four months) in the last year. But she will be eligible in a few months. I hope by then we won’t need one more.