An investigation is underway of a possible poliovirus outbreak in London.
The threat to public health is very low, but this is a good time to make sure you’re up-to-date on polio vaccines! Many kids have fallen behind on the vaccine schedule during the past 2+ years.
In the UK, babies get vaccinated for poliovirus at 8 weeks, 12 weeks, and 16 weeks as part of the “6-in-1 vaccine.” A booster is included in the pre-school booster series given age age 3 or 4, and in the teenage booster given at age 14.
In the United States, polio vaccine is routine at 2 months, 4 months, and between 6 and 15 months. A booster is given between ages 4 and 6. If you’ve missed any of these appointments, it’s time to catch up now!
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The virus was detected in several wastewater samples taken between February and May in a wastewater treatment plant that serves North and East London. The strain of virus is a “vaccine-derived” poliovirus type 2. This takes a bit of explaining.
There are two kinds of vaccine for polio. Both have been around for a long time–since the 1950’s/60’s. Many people who are now grandparents will remember getting their polio vaccines at school, either as a shot or in a sugar cube.
In both the UK and the US, and in many other places, young children receive an *inactivated* polio vaccine (IPV) as an injection. This vaccine cannot cause an infection. Similar to other inactivated vaccines, it’s made with cultured poliovirus that has been killed using laboratory processes. Inactivated virus vaccines often take several doses to offer lifetime immunity, which is why kids get 4 or 5 doses in a series. Other inactivated vaccines include those against Hepatitis A, rabies, and influenza.
In low-income settings, the oral polio vaccine (OPV) is often given instead. OPV is preferred in low-resource settings and mass vaccination campaigns because it does not require a health professional or sterile needles to administer. This is a live attenuated virus vaccine. That means it contains live virus that has been weakened so that it replicates poorly. But it DOES cause a mild infection in the intestine. This is actually considered an advantage of OPV because the low-level exposure to shed viral particles can help immunize people who didn’t get to the vaccination clinic. However, in very rare instances, OPV can cause an infection severe enough to require medical attention. In the 60+ years this vaccine has been used, there have been a few cases where it even caused paralysis.
The virus found in the current outbreak has been identified as a vaccine-derived strain. That means this outbreak originated with someone who received the oral poliovirus vaccine abroad (since it’s not used in the UK), and it has spread to other unvaccinated people in close contact with one another.
UK health officials are actively working on the outbreak. It’s nothing to panic about.
💉 Just get your kids up to date on their vaccines. 💉
NHS Press release about the outbreak
Childhood vaccine schedules:
for the UK and for the US
Polio general info:
