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 immunization programs, which aim to achieve herd immunity or 95% uptake. This is an important number to remember through this article. 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 immunization programs, 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 vaccines on to the national schedule in the first place, finding the unimmunized population, and driving population uptake. Before discussing these, let’s have a look at how immunization uptake differs between the two countries.
Comparing two different national immunization programs is difficult given the variation in immunization schedules and combined vaccines, however, the World Health Organisation (WHO) suggests we can gain insight to overall quality and performance by comparing immunization and disease rates for measles and rubella. For example, let’s look at the metrics for measles.
Data below 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 95% in the US and 90% in the UK (2019/20). This level of uptake may appear high but does not confer 95% her immunity–remember?
Missing from these graphs is a useful, comparable incidence rate. Based on calculations, the US saw 0.004 per 100,000 population and the UK had 1.2 per 100,000 population (2020). 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 could be soon to follow (measles free status was established in 2000), with the US Center for for Disease Control (CDC) reporting significant numbers of measles cases in 2019 and 2020. However, no cases have been reported in 2021 so far in the US.
Key differences in approach
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 immunization schedules has been challenging.
My challenge started when 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 midwife in the NHS, but we were able to make it happen. The Meningitis B vaccine is unique to the UK, but since we live in the UK that was easy to get. However, the Chickenpox vaccine was much trickier. It is not easily accessible to patients in the UK and here is why…
The database includes (almost) the entire population and supports a central invitation process to invite the entire eligible population to be vaccinated.
Independent committees in both countries are responsible for critically appraising a vaccines evidence for 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 Immunizations (JCVI).
The context in which both make decisions impacts on recommendations. In the UK, where healthcare spend must maximize 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 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 UKs 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, hospitalizations, 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.
The nation versus the state
Another key difference between the US and UK immunization programs is how each manages performance to achieve herd immunity. The UK has two unique tools: a national patient database and regional immunization coordinators. The database includes (almost) the entire population and supports a central invitation process to invite the entire eligible population to be vaccinated. This is especially useful in an outbreak scenario, such as COVID-19. Program managers also support providers to audit and understand variation in uptake.
The US influences uptake through the education system by requiring all school children to be immunized. This is upheld by State laws but varies considerably across 50 states.
The variation in state laws range from allowing exemptions for philosophical reasons to only allowing medical exemptions by a doctor who has received annual, specialist training. The doctor must expressly note whether the exemption is temporary or permanent and for which vaccinations the exemption is written. Additionally, a thorough review of the case must be carried out by a Public Health Immunization Officer—way to go West Virginia! Unsurprisingly, states with the most stringent policies and laws benefit from the highest vaccination uptake rates.
“Given the falling immunization rates in both countries, it could be time to consider if these additional strategies could help to establish herd immunity once again”
Combating vaccine hesitancy
Vaccine hesitancy is a public health challenge faced by healthcare professionals in both countries. Patients have access to an incredible amount of information–some find it difficult to make sense of it all and have genuine concerns that need addressing. Constrained appointment times add to the challenge of engaging patients in meaningful conversations which also allow for time for technical explanations.
In the past, where specific groups have been vaccine hesitant, public health work to engage thought leaders has helped to improve uptake. In the 1990s for example, WHO engaged Muslim and Jewish faith leaders to clarify the acceptability of vaccines containing pork gelatine. This type of public health work, especially at the grassroots level, can have a big impact on population uptake.
If we think about what has led to disease eradication (smallpox, rubella, and measles—if only temporarily) most would conclude that vaccines have made this possible. In truth however, vaccines are tools that are a part of a public health strategy.
The US and UK, with very different health and political systems, face different challenges and can celebrate their unique achievements. The US has boldly used immunization mandates for school children. This has proved to be an effective strategy – where state laws and policies are most stringent, uptake is highest and vaccine-preventable disease incidence is lowest. Central invitation systems with the support of performance managers have also proven to be effective. Given the falling immunization rates in both countries, it could be time to consider if these additional strategies could help to establish herd immunity once again.
The key thing to remember when introducing a new vaccine into a national immunization schedule is that disease can be eradicated, but only if the program is politically supported, well resourced, and acceptable to patients.
I would like to extend special thanks to the following academics and experts who supported me in the creation of this article:
Dr Elizabeth Grant, Family Medicine Specialist in Helena, Montana
Sarah Kolman, RN, MA Registered Nurse and Health Coach in Lander, Wyoming
Dr Arthur Reingold, Professor and Head of Epidemiology at School of Public Health, University of California, Berkeley, and ACIP participant.
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