|3rd October 2019
In a local English church yard, not far from where I live, a single head stone stands for three children who died in quick succession, one after another, in the spring of 1887. Gone are the days of blaming miasmas and bad humours for such tragedies. We understand infectious diseases so well that we can control them, even eradicate them from this earth.
The success of infectious disease control depends in part on the strength of national immunisation programmes, which aim to achieve herd immunity – 95% of the population are immune to a contagious disease. When herd immunity is achieved, it is very difficult, if not impossible, to spread infection from person-to-person. Both the US and UK have well-resourced national immunisation programmes, however, they use unique approaches to achieve herd immunity given their different health and political systems. They also have unique challenges which include, getting a vaccine on to the national schedule in the first place, finding the unimmunised population, and driving population uptake. Before discussing these, let’s have a look at how immunisation uptake differs between the two countries.
Comparing two different national immunisation programs is difficult given the variation in immunisation schedules and combined vaccines, however, the World Health Organisation (WHO) suggests we can gain insight to overall quality and performance by comparing immunisation and disease rates for measles and rubella. For example, let’s look at the metrics for measles.
“The UK lost its measles-free status and the US is soon to follow”
Data above shows the US and UK have similar uptake of a single dose of a measles containing vaccine (MCV), about 92% (2018). Uptake of dose two was 94% in the US and 88% in the UK. This level of uptake may appear high but does not confer 95% herd immunity. However, missing from these graphs is a useful, comparable incidence rate. Based on calculations, the US saw 0.11 cases per 100,000 population and the UK had 1.81 per 100,000 population (2018).
Also missing from these graphs are data from 2019. Vaccine rates continue to fall in both countries and across Europe case numbers have dramatically increased because herd immunity has not been maintained. Consequently, the UK lost its measles-free status (established in 2016) and the US is soon to follow (status established in 2000), with the US Center for Disease Control (CDC) reporting more measles cases so far in 2019 than it saw in 1992.
“In the UK, where healthcare spend must maximise population health across all health conditions, cost-effectiveness matters a great deal to decision makers”
Readers are already well aware that the US healthcare system has a complex web of independent hospitals, clinics, and providers, whereas the UK has a single national health service (the NHS). As an American expat living in the UK, a patient, a mother and nurse, I’ve come to understand both systems well. I will be the first to say, navigating both health systems for the purpose of ensuring my daughter is up-to-date with both the UK and US immunisation schedules has been challenging.
My challenge started when my daughter Anna was born. The Hepatitis B vaccine is given at birth in the US, and at the time, this was not a part of the UK schedule. It took a bit of preplanning with my NHS midwife, but we were able to make it happen. The Meningitis B vaccine is unique to the UK and since we live in the UK that was easy to get. However, the Chickenpox vaccine was much trickier.
Independent committees in both countries are responsible for critically appraising the evidence of a vaccine’s effectiveness and putting forward recommendations to government for new vaccines on, or amendments to, the national schedule. In the US this is The American Committee on Immunization Practices (ACIP) and in the UK it is the Joint Committee for Vaccination and Immunisations (JCVI).
“The US influences uptake through the education system … but this varies considerably across 50 states”
The context in which both make decisions impacts on recommendations. In the UK, where healthcare spend must maximise population health across all health conditions, cost-effectiveness matters a great deal to decision makers. Vaccine funding is most likely to be agreed when costs come in below the willingness-to-pay threshold. In the US cost effectiveness is considered, but the ACIP does not rely heavily upon it. As a result, the consideration of cost-effectiveness is a key difference in the vaccine schedules between the US and UK.
The chickenpox vaccine, for example, was recommended for the US schedule by ACIP in 1996. However, JCVI considered the cost of the vaccine in addition to costs associated with shingles infection (reactivation of the chickenpox virus) and concluded that adding the vaccine to the UK national schedule would not be cost-effective.
Subsequently, the US has achieved good uptake of the vaccine and with the fall in chickenpox incidence has seen a reduction in outbreaks, outpatient appointments, hospitalisations and deaths.
I did manage to get the chickenpox vaccine for Anna when I was last in the USA. Conveniently, it was just prior to a rush of chickenpox infection that went through her nursery upon our return. I couldn’t help but feel a little smug when she didn’t get sick.
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