Vaccines work by mimicking disease agents that make us ill, causing acquired immunity so that when your body encounters the real disease-causing agent it is ready to mount a defence. The vaccine can be made of killed or weakened forms of the disease-causing agent (such as bacteria or viruses), its toxins or its surface proteins. More information about vaccines in general can be found at the Wikipedia page on vaccines.
Vaccinations have greatly reduced the prevalence of diseases and they continue to be important for global health today. The World Health Organization (WHO) estimates that vaccination averts an estimated 2 to 3 million deaths every year.1 However, if vaccination coverage is improved an additional 1.5 million deaths could be avoided.2 The number of under-vaccinated children in Nigeria has rapidly increased, with 3.4 million children going without the DTP3 vaccine (compared to 2.9 million in India).
The low price of vaccines compared to other health interventions has made them especially attractive as a way to improve global health and today they reach billions of people around the world. All countries implement some kind of routine childhood vaccination program. As vaccines can disrupt transmission of infection, they not only protect the vaccinated individuals but the wider community also. These public health benefits are the reason why some governments pay all or part of the costs of vaccinations in national vaccination schedules. In addition to governments there are a large number of other institutions that contribute to vaccination efforts. These include non-governmental organisations (NGOs), public health institutions such as the World Health Organization (WHO) and more recently the public-private partnership Gavi (the Vaccine Alliance).3
There is a technical difference between vaccination and immunization, as the National Health Service (NHS) explains: “Vaccination means having a vaccine – that is actually getting the injection, or nasal spray or oral vaccine. Immunization means both receiving a vaccine and then becoming immune to a disease”. The distinction is made because in a very small number of those who are vaccinated the vaccination will not ‘take’ and therefore that vaccinated person will not be immunized (i.e. will not be immune to the disease). However, as this refers to a very small number of people both terms are often used interchangeably across the academic literature and in media reporting and we will follow this convention in this entry.
An early form of vaccination was called variolation (more broadly referred to as inoculation). Practised in Asia, this was an ancient technique of deliberate smallpox infection with dried smallpox scabs blown up the nose to expose the person to a form of the disease which was often milder.4 By the 1700s variolation had spread to Africa, India and the Ottoman Empire, followed by the UK and America, where the method of infection more frequently used was a puncture to the skin.5 Variolation did work for many people, but there were risks. Those variolated could contract the more severe form of smallpox and die, and they could also transmit the disease to others. In 1796 English physician Edward Jenner demonstrated another method of inoculation, using cowpox, a similar disease that had previously been observed to protect against smallpox. Jenner conducted an experiment using matter from a cowpox lesion to inoculate his gardener’s eight-year-old son James Phipps. Two months later Jenner exposed the boy to smallpox lesion matter and when Phipps did not develop smallpox, it showed he was protected against the disease.6 Jenner called the procedure ‘vaccination’.
Following the findings of Jenner as the first scientific attempt to control disease by vaccination, the smallpox vaccine went through many iterations, with the newer vaccines produced by modern cell culture techniques (passing the virus through cell culture makes the vaccine safer). By the middle of the 20th century confidence grew that smallpox could be the first disease eradicated by humankind. In 1967 the WHO launched a global eradication of smallpox program. Mass vaccination of over 80% of a country's population ensued but people who were nomadic or lived in politically unstable regions posed particular problems. A number of innovations came in the development of foot-powered injector called the “ped-o-jet” and then the bifurcated needle, which was efficient and cost-effective to use.
In order to reach large sections of population, epidemiologist William Foege developed Eradication Escalation (E2) to contain smallpox outbreaks during October (the seasonal low point of smallpox transmission where prevention of a case could stop a smallpox chain transmission). Other obstacles faced included forcibly vaccinating an Indian religious leader to convince his followers to be vaccinated, negotiation of ceasefires for vaccine transport in war-torn Nigeria, vaccinating in concentric rings around an outbreak, and cash bounties to reward the reporting of smallpox cases. Finally in 1977 the last case of naturally contracted smallpox was reported in Somalia, in Ali Maow Maalin, and in 1980 the WHO announced that smallpox had been eradicated.
Eradication is the ultimate goal of vaccination against a disease. For other diseases, a vaccine has been less forthcoming. The first visualization below shows a timeline of innovation in the development of vaccines. Each bar begins in the year in which the pathogenic agent was first linked to the disease and the bar ends in the year in which a vaccination against that pathogen was licensed in the US.
For some diseases there has been a relatively short timespan between when the infectious agent was linked to the disease and a vaccine was developed. The quickest was 10 years for measles, with the agent linked to the disease in 1953 and the vaccine licensed in the U.S. in 1963. Malaria is proving harder as it has been over 135 years since the agent was linked to the disease. A vaccine is now in development – RTS,S is undergoing pilot trials in select countries after being approved by European regulators in 2015. Vaccine innovation has followed both scientific and political-economic developments:
- Bacterial culture techniques which allowed the development of bacterial vaccines for diphtheria, tetanus, and pertussis in the early 1900s.7
- The first and second world wars prompted combined efforts by universities, governments, and private companies.8
- By the 1950s viral tissue culture techniques allowed the development of vaccines against polio, measles, mumps, rubella, and varicella (chickenpox).
- New technologies in molecular biology and advanced chemistry techniques have most recently led to vaccines against hepatitis B, flu, and pneumococcus, which causes meningitis.9
The most common and serious vaccine-preventable diseases tracked by the World Health Organization (WHO) are the following:10
- Diphtheria, tetanus, and pertussis (DTP3): are all bacterial diseases and they are often grouped together as a combination vaccine against all three diseases is commonly used.
- Diphtheria primarily infects the throat and upper airways and is fatal in 5 – 10% of cases.
- Tetanus is not passed person-to-person but through spores of a bacteria living in soil and animal intestinal tracts. These bacteria enter the body through wounds and release a toxin that affects the nerves, which causes muscle stiffness and spasms.
- Pertussis is a highly contagious disease of the respiratory tract. Children who contractpertussis tend to have coughing spells that last four to eight weeks. Vaccinating health workers and pregnant women is the most effective strategy for preventing disease in infants too young to be vaccinated.
- Haemophilus influenzae type b (Hib): is a bacterial infection that causes meningitis and pneumonia transmitted through the respiratory tract from infected to susceptible individuals.
- Hepatitis B (hepb): is a highly contagious viral infection that attacks the liver and is transmitted through contact with the blood or other body fluids of an infected person. As the chart below shows is estimated that about 100,300 people die each year due to consequences of hepatitis B. WHO recommends that all infants should receive their first dose of vaccine as soon as possible after birth, preferably within 24 hours.
- Poliomyelitis (Pol3): is a highly infectious viral disease. Once the poliovirus invades the nervous system it can cause irreversible paralysis in a matter of hours. No cure exists for polio, only treatment to alleviate symptoms. As we detail in our separate entry on polio the world is on its way to eradicate the disease thanks to the vaccine against the virus. While in the 1980s there were 350,000 paralytic cases of polio every year, the world saw only 42 cases in 2016.
- Measles, mumps, and rubella (MMR): are all viral diseases.
- Measles is a highly contagious killer of young children globally, despite a safe and effective vaccine being available. Around 70,000 people die because of measles every year, the huge majority of whom (87%) are children younger than 5 (falling from 90,000 in 2016).
- Mumps infection occurs via direct human contact or by airborne droplets. It causes painful swelling at the side of the face under the ears (the parotid glands), fever, headache and muscle aches. It can cause sterility in teenagers and adults.
- Rubella is usually mild in children, but infection during early pregnancy leads in 90% of cases to fetal death or congenital rubella syndrome, which can result in serious defects of the brain, heart, eyes, and ears.
- Meningococcal meningitis (‘MenA, B, C, W X and Y’): is a bacterial disease which can cause severe brain damage and is often deadly. Transmitted through contact with respiratory droplets or secretions, it kills more than 120,000 people every year.
- Tuberculosis (TB): is a bacterial disease transmitted by people infected with pulmonary (lung) TB. The BCG vaccination is only partially effective providing some protection against severe forms of TB in children but is unreliable against adult pulmonary TB. 1.2 million people die because of TB every year.
- Yellow fever (YF): is a viral disease transmitted by infected mosquitoes. There are 42 countries and territories at risk for yellow fever in Africa and the Americas. In these 42 countries and territories, vaccine coverage is estimated at 45%.
The WHO have a larger list of 26 diseases for which vaccines are available (including pneumococcal disease, varicella/chicken pox, HPV, Hepatitis A and rotavirus). Also many vaccines are currently in the pipeline of development.
The time-series plot below shows the number of deaths caused by some of these diseases over time. By selecting ‘change country’ it is possible to see this change for any country in the world.
Additionally there is the possibility to see this change as a bar chart here.
The visualization below shows the reduction in cases and deaths from vaccine-preventable diseases in the United States after the introduction of each vaccine. This data was published by Roush and Murphy (2007)1 and the data can be viewed in a table here.
For several diseases the US has achieved a 100% reduction of cases and deaths and for many other diseases the reduction is often very substantial as well.
Reduction of cases and deaths of vaccine-preventable diseases in the United States after the introduction of the vaccine.2
The development of the vaccine against measles and the history of measles in the US
The introduction of a vaccine was however not the only reason for progress against these diseases as the visualization below shows. The case-fatality rates of measles was falling in high income countries such as the US prior to the introduction of the vaccine in 1960 – this is best seen by switching from the linear to the logarithmic axis. Improved living conditions and medical advancements meant that contracting measles was less and less likely to be fatal.
The rate of cases however was virtually unchanged until after the measles vaccine was introduced – as our visualization below shows.3
A visualization showing the total number of cases and deaths can be seen here.
Supply constraints have caused problems for country access to vaccination. One-third of 194 countries have run out of a vaccine for a month or longer (according to data submitted to WHO and UNICEF of average year between 2011 and 2015) and this includes both higher and lower income countries. In the US, the Centers for Disease Control and Prevention (CDC) stated that reasons for shortages as were multi-factoral from: "...companies leaving the vaccine market, manufacturing or production problems, and insufficient stockpiles". The supplies of vaccines that are critically low include those that target yellow fever, hepatitis B, cholera, meningitis C, diphtheria, whooping cough, tetanus, hepatitis A, and tuberculosis.
Concerns about the supply of vaccines in an epidemic or pandemic have been raised. For example, the supply of yellow fever vaccine was limited for the outbreak in Angola in 2016 leading to the recommendation of a fractional dose to extend existing supplies.4 Laurie Garrett argues that because the drug had become so cheap (60 cents for each vaccine 2008) few companies wanted to make it and world stocks of the vaccine were nearing zero, forcing the WHO to dilute donated vaccines from countries like Brazil (which sent 18 million doses) by 5 to 1 with the hope they would still work. Romania experienced a situation of parallel vaccine exports in 2016 where more vaccines were exported than was supplied to meet the country's needs. A shortage of the measles, mumps, and rubella (MMR) vaccine was partly responsible for the measles outbreak in 2016-17.5
There are five big pharmaceutical companies that account for 80% of vaccine production: Sanofi Pasteur, GlaxoSmithKline, Merck, Pfizer, and Novartis.6 Many vaccines are only provided by one or two suppliers. For newer vaccines there are often particularly few suppliers due to the high investment needed to develop a vaccine and also having patents attached can also lead to high profits. Prevenar, the brand name for the pneumococcal vaccine (PCV), was hugely profitable for the pharmaceutical company Wyeth (purchased by Pfizer in 2009), with sales in 2005 of $1.5 billion. One vaccine for tetanus and diphtheria (td) has a large number of suppliers (at 13 and 7 for the paediatric formation).
The WHO reports that vaccines that are supplied by more suppliers have a more competitive environment and this ultimately drives down prices.7
As a share of the global pharmaceutical market worth over $1 trillion a year, vaccines make up a small proportion of $24 billion or about 2.4 percent. In the past vaccines were often viewed as less profitable treatments for pharma companies, which led to a lack of investment and some companies pulling out of production altogether.8 But this has changed as the revenue of the global vaccines market has increased and richer country governments and insurance companies have been willing to pay more for new vaccines. In addition, growing economies such as India and China are spending more, and poorer countries now have Gavi to help governments pool resources and make advance purchase commitments.9 These emerging economies are also able to produce more of their own vaccines. For example the Serum Institute in India is the world's largest vaccine manufacturer by number of doses produced and sold globally.
New vaccines tend to be more expensive as they have patents attached. For example when the HepB vaccine was developed many lower income countries could not afford to pay $30 a dose.10 Today there is often a differentiation between the prices paid by richer and poorer countries.
Price differences for vaccines between the US and developing countries11
|Vaccine||Cost per dose in a developing country||Cost per dose in the US|
|HepB||$0.58 - 13.20||$50 - 100|
|BCG||$0.16 - 1.11||$100 - 200|
|Yellow fever||$4.30 - 21.30||$50 - 100|
Some vaccines still remain more expensive. For example, the pertussis vaccine either comes in two versions: whole cell (wP) where the whole pertussis organism is contained or acellular (aP) where part of the pertussis organism is contained. The pertussis vaccine is combined with diphtheria and tetanus to produce either a DTwP or DTaP vaccine. DTaP is more expensive; it is sometimes called 'the painless vaccine' because it causes less of a local reaction and pain but should not be given to children over the age of seven. However, DTwP has been shown to prevent the transmission and spread of disease to unvaccinated people and to those with weak immunity because it is more efficacious.
We provide detail on three vaccinations: DTP3, measles, and polio. These diseases were the original ones targeted by the WHO for their Expanded Program on Immunization (EPI). Mass vaccination coverage expanded greatly through the Expanded Programme on Immunization (EPI). The EPI was initiated by the WHO in 1977 to build on the success of smallpox eradication and the goal was universal immunization. The first diseases targeted by the EPI were diphtheria, whooping cough, tetanus, measles, polio, and tuberculosis.
Diphtheria, Tetanus, and Pertussis (DTP3) – global vaccination coverage and decline of the disease burden
The chart below shows the progress over time of DTP3 immunization coverage for children around the world. By clicking on any country you can see the change in that country over time.
The WHO reports in 2016 that 86% of infants worldwide (116.5 million infants) received 3 doses of diphtheria-tetanus-pertussis (DTP3) vaccine. Also in 2016 130 countries had reached at least 90% coverage with the DTP3 vaccine.12 If we look at the change over time by world region it is South Asia in particular that stands out. While 85% of one-year-olds today are immunized, that same figure was as low 6% in 1980.
Within each country there can be substantial differences in vaccination coverage. The WHO reports that in all regions children in the richest 20% of urban households are more likely to get immunized than children from the poorest 20% of households.
Some countries lag behind however. Ukraine stands out as having particularly low DTP vaccination rates in 2015 of 23%, falling from 98% in 1999. Ed Holt writing for the Lancet in 2013 attributed the decline to: "A combination of public mistrust in vaccinations, poor vaccine supply, and corruption in the health system".13
The world map shows the share of children vaccinated against measles.
You can switch to the 'chart' view to see the global coverage against vaccines. The measles vaccine was developed in 1963. In 1983 – the first year for which global data is available – only every second child was vaccinated against measles. In the latest data this share has increased to 85% globally up from 72% in 2000.14 The sub-Saharan African region achieves the lowest measles vaccination rates, along with conflict-ridden and unstable countries (e.g. Syria, Afghanistan, and Iraq). But also some of the Pacific Islands – such as Papua New Guinea and Vanuatu – are performing poorly.
Today (2014 numbers) 114.3 million children are vaccinated against measles every year, this is on average 313,071 children every single day.15
The WHO estimate that 164 countries had included a second dose as part of routine immunization and 64% of children received two doses of measles vaccine according to national immunization schedules.16 Two doses are needed for a higher level of protection.
This scatterplot compares the vaccination coverage against measles with the coverage against DTP3.
Global decline of measles
The visualization below shows the discussed increase of the global vaccination coverage of one-year-olds and the simultaneous decline of reported cases of the disease; from close to 1,000 cases per million people globally to 28 cases per million. This represents a 33-fold reduction.
Country by country you can see the change over time in this visualization here.
Polio is targeted for global eradication and we present the empirical evidence on this fight in an entry entirely dedicated to polio.
The WHO estimate that in 2015, 85% of infants around the world received three doses of polio vaccine.
The number of paralytic polio cases have decreased by over 99% since the 1980s, from an estimated 350,000 to 400,000 cases per year to fewer than 100 cases per year today.
While the benefits might possibly be forgotten as vaccine-preventable diseases have lost their threat thanks to the introduction of the vaccines it is still true that people around the world – including those in richer countries – continue to benefit from vaccinations.
To see how we are benefiting from vaccinations it is necessary to compare the suffering before and after the introduction of the vaccine. To show this we have visualized the data by Roush and Murphy for the US reduction in mortality for vaccine-preventable diseases in the graph above.
Below we show the evidence on one of the greatest successes of global health. Smallpox, which just decades ago killed several hundred thousand people every year was successfully eradicated in 1980 thanks to the vaccine.17
The Gapminder Ignorance Project studied how well-informed people are about global development. The visualization below shows what people perceive to be the status in global vaccination efforts.
Americans greatly underestimate the successful expansion of vaccination around the world. Only 17% of the American public know that around 80% of the world's children are vaccinated against measles.
Result from the Gapminder 'Ignorance Test'18
Vaccines typically cause acquired immunity via some agent inside the vaccine that resembles the disease-causing microorganism. The agent can be made of killed or weakened forms of the microorganism, its toxins or its surface proteins. More information about vaccines in general can be found at the Wikipedia page on vaccines.
There is a collective social benefit in more people vaccinating. For most diseases, the greater the share of people who are immunized, the better protected is everyone in the population as the disease transmission can be stopped. Herd immunity is a community protection that is produced when a high percentage of the population is vaccinated, such that it is difficult for infectious diseases that are contagious to spread.19
Herd immunity provides a protective barrier, especially also for those who cannot be vaccinated. These include vulnerable groups such as babies too young to be vaccinated or immune-compromised children who are the first potential victims of low vaccination rates.
When a person is immune to a disease they can act as a barrier to slow down or prevent the transmission of disease to other people. When the number of people in a population that are immune against a disease is reached, such that a disease no longer persists in the population, this is called the herd immunity threshold (HIT). The table below shows the HIT for several diseases. Measles and pertussis are very contagious airborne diseases and a larger share of people need to be vaccinated to stop the transmission. Because of this these diseases have the highest HIT rates that need to be reached.
Herd Immunity Thresholds of vaccine-preventable diseases20
|Disease||Transmission||Basic reproduction number||Herd Immunity Threshold|
II.2 Determining impact: Why do vaccine schedules differ and what is the effect of vaccination compared with better hygiene?
Chickenpox (varicella) is an example of a vaccine that some countries adopt into their routine childhood vaccination schedules, while others do not. The question that follows is why there is a difference in opinion for introducing widespread uptake of a vaccine or not. Japan was one of the first countries to adopt universal chickenpox vaccination.21
Most European countries do not vaccinate against chickenpox, except for 'at risk' groups. The main reason for not adopting universal vaccination is the high cost. Additional supporting justifications are that it is usually a mild disease and the benefit of fewer cases of shingles – as explained here.
The Centers for Disease Control and Prevention in the US ran the Varicella Active Surveillance Project (VASP) from 1995 through to 2010 to monitor the impact of the varicella vaccination program and the key finding is shown in the chart below. The coverage of the vaccine in Los Angeles County rose from 37.9% in 1997 to 95.1% in 2010, and in Philadelphia from 41.2% in 1997 to 94.6% in 2010 (one-dose vaccinations for children between 19 and 35 months of age). By 2010, varicella incidence declined by 98% in Antelope Valley (California) and West Philadelphia (Pennsylvania) compared with 1995. Outbreaks and hospitalizations also decreased rapidly. From 1995 to 1998, hospitalization rates ranged from 2.2 to 3.3 per 100,000 population but by 2006-2010 this had declined to 0.2 per 100,000 in Antelope Valley and 0.5 per 100,000 in Philadelphia.
Chickenpox can also help to answer the question of whether better hygiene or vaccination are in fact responsible for the reduced rates of disease. Although both are important, a more recently adopted vaccination such as chickenpox can demonstrate the effects of vaccination in reducing the rate of disease after the importance of hygiene was discovered and became a preventative measure against disease. The impact on disease rates demonstrate it is not hygiene but vaccination that reduced the incidence of chickenpox so dramatically in the US.
Chickenpox incidence in two counties in the US, 2000-201022
Anti-vaccination opposition is as old as mass vaccination itself. The original anti-vaccination organisation 'Anti-compulsory Vaccination League' was established in the UK in 1866 as a protest against smallpox vaccination mandates. In the late 1880s and 1900s opposition to vaccines in the U.S was organised through the 'Anti-Vaccination League of America' and the 'American Medical Liberty League'.23 At that time resistance could be attributed to concern about the safety and efficacy of vaccines, which were an unregulated industry along with a dislike for the extension of state powers.
Since then, vaccine resistance in both higher and lower income countries has been attributed to a mixture of reasons including safety concerns and suspicion of state power. In higher income countries a number of controversies have arisen due to fear and uncertainty about side effects. In the 1970s and 1980s the DPT vaccine was questioned in connection with permanent brain injury or encephalopathy, but studies would show no connection. In the late 1990s and early 2000s MMR was connected with bowel symptoms and autism by a 1998 paper authored by Andrew Wakefield and others. The paper was later retracted by the journal (The Lancet) and Wakefield struck off the UK medical register after results were found to be fraudulent.24
In lower income countries examples of opposition can be seen in worries about government powers. In Channai (Madras) India the 1950s, oppostion to BCG vaccination was a regional push-back against the will of nationalist and outside post-colonial forces.25
Resistance to polio vaccination in some majority Muslim countries has also been attributed partly to underlying political reasons. There are only three countries that have never been able to stop the transmission of polio: Afghanistan, Nigeria and Pakistan. Jonathan Kennedy and Domna Michailidou explain some of the political dynamics behind the low vaccination rates in Nigeria and Pakistan. In Nigeria the opposition to the vaccine reflected political shifts where a majority Muslim population in the North feared the intervention of the newly appointed Christian majority government. In Pakistan Pashtun communities resist the expansion of the Pakistani state and Pakistani Taliban hostility was fueled by the fake hepatitis vaccination campaign led by the CIA to try to gather DNA to help find Osama Bin Laden. In Afghanistan it appears that supply problems persist in a post-conflict country.26
Results from the Vaccine Confidence Project
To view vaccination beliefs and attitudes on a global scale across countries, researchers at the Vaccine Confidence Project have begun to measure skepticism of vaccination.
The world map shows that in most countries the huge majority considers vaccines to be safe. But in some countries – several former Soviet countries, France, and Japan – a substantial share of the population disagrees. In France 41% of the population does not consider vaccinations safe. In other countries the share that is of the same opinion is smaller than 10% (in Bangladesh only 0.2%).
Beliefs and attitudes do not translate straightforwardly into behaviour. Even for countries where a large share of respondents had a high level of skepticism of the safety of vaccination, coverage rates may remain high.
Countries vary in whether vaccination is compulsory, required (according to specific mandates), or voluntary. Which policy is followed has depended much on historical legacy, which becomes clear when one considers some of the different regulations and their history around the world:
Compulsory vaccination: Many Eastern Bloc countries introduced compulsory vaccination during the communist era. Vaccination was previously compulsory in Romania for example and after a drop in vaccination rates the country is going through the process of reintroducing compulsory vaccination. The same is true for Italy and also France, which had compulsory vaccination for three diseases but increased this number to 11 in 2017/8 in response to a drop in vaccination rates.
Vaccine requirements and mandates: The US has mandates for vaccination where vaccination is required to enter state school or daycare. An early case in the US paved the way for state jurisdiction to protect public health in light of personal liberty.28 In Jacobson v. Massachusetts (1905) the Supreme Court ruled that states have the authority to require vaccination against smallpox during a smallpox epidemic. Since then the United States has had a history of school vaccination requirements. The increased number of children in public schools as a result of the compulsory school attendance law led to an increased risk of smallpox outbreaks, through close contact in large crowded classrooms.29 Similarly in Australia two policies penalize parents for not vaccinating their children. The 'No jab no play' policy removed state-sponsored childcare. The 2016 'No jab no pay' policy removes state welfare by not providing the universal 'Family Allowance' welfare payments for parents who are conscientious objectors of vaccination.
Voluntary vaccination: Some countries where vaccination is voluntary had early pushback against vaccination, as with the UK and the Netherlands. In 1853 a law was passed in England and Wales requiring universal vaccination against smallpox, but opposition from anti-vaccinationists led to laws being passed to allow for conscientious objection.30
Vaccination for country entry: For countries in Africa and South America where yellow fever is endemic or where the mosquito vector is present a certificate of proof of vaccination is required. Only then will the country issue a visa upon entry to that country to prevent importation of this disease (particularly if travellers come from, or have visited yellow fever endemic areas).31 In past centuries (17th to 19th), yellow fever was transported to North America and Europe, causing large outbreaks that disrupted economies, development and in some cases decimated populations. Throughout the 18th and 19th century, yellow fever was among the most feared diseases in the ports of the Old and New World. Saudi Arabia is the only country that requires the additional vaccinations of meningococcal disease and polio for pilgrims visiting Mecca.
Whether compulsory vaccination results in improved vaccination rates is not a straightforward question to tackle because it is highly dependant on country context (reasons for compulsory vaccination), historical circumstance, cultural and social norms, as well as the practicalities of implementing and enforcing such a law. Certainly in Eastern Bloc countries whether vaccination was compulsory vaccination rates have been high but it is unclear whether to attribute this to the law or the behaviours and mechanisms of compliance under communist rule. Certain vaccinations have historically been compulsory such as smallpox, polio, and yellow fever. Here vaccination rates have also been high but it has also encouraged organised opposition to vaccination and public discontent. This is a major worry of public health authorities that a relationship of trust, between governments and citizens is threatened (particularly for health where a rhetoric of self-responsibility, personalisation, and choice is encouraged). There are countries with high vaccination rates without compulsory vaccination and governments do not want to disrupt public trust and self-responsibility by making vaccination compulsory, particularly if it is not seen as needed. It has been argued that high coverage has been achieved through "other approaches or efforts" and so acceptance of compulsory vaccination might be problematic in countries such as Sweden, Norway, Denmark, the Netherlands, and the UK.32 In recent years governments have acted in response to epidemics to make vaccinations compulsory, as we have seen for 2017-18 with compulsory vaccinations in France, Italy, Germany, and Romania.
One country where we can see variation in vaccination policy and the effects this has is the US. In the US states decide on what exemptions are allowed for the mandate for children to receive vaccinations to access education and daycare. The reasons for such laws in the first place came with a free, public education system, which also unfortunately meant schools became sites of epidemics for childhood diseases. Exemptions are granted for medical reasons but many states also allow for philosophical, personal belief or religious exemptions. Only three states – Mississippi, West Virginia, and California – only allow for medical exemption. Californian immunization rates have increased following a new Senate Bill SB 277 in 2015 to remove non-medical exemptions to vaccination. We can see on the chart below that there is not a strong correlation between stricter requirements for vaccination (i.e. only allowing for medical exemptions). Indeed Mississippi does often top the list as having the highest vaccination rates and only medical exemptions are allowed in the state but also starkly Mississippi residents are also the consistently the unhealthiest and poorest in the entire country. Health outcomes are very poor and most cannot afford healthcare (the state has the highest percentage without health insurance in 2017) and so perhaps it is unsurprising that resident accept subsidized vaccinations that are required in any case for access to childcare and state schools (without the option for home or private schooling where vaccines are not required).
Vaccination coverage of children, by US state in 2016/17
33 Questions have arisen about how accurately parents can recall child immunization history and the limitations of phone calls to collect data.
Even accurately estimating target populations in low-income settings can be difficult and discrepancies have been found when comparing country-reported figures to independent surveys.34
Furthermore, childhood vaccinations are rarely considered altogether. The DTP3 vaccination tends to be the vaccination most often used as a marker of strength in a country’s immunization programs, since three administrations of the vaccination are required.35
National coverage rates are what is focused upon, but even when national coverage are high, subnational coverage can reveal inequities, which is why the WHO and UNICEF are increasing efforts to gather high quality subnational coverage data.36
In 2015 coverage estimates at the district level, were only reported for 158 of the 194 WHO Member States. National data only provides part of the picture of immunization coverage. Different levels of coverage data, including at sub-national or district level is useful for gaining an understanding of where there might be clusters of under- or un-vaccinated children.
World Health Organization - Immunization surveillance, assessment and monitoring
- Data: Immunization coverage, system indicators and schedule, and disease incidence
- Geographical coverage: WHO member nations
- Time span: 1980 onwards for many countries
- Available at: Online here
- Data: Percent of one-year-olds immunized
- Geographical coverage: UN member nations
- Time span: 1980 onwards for many countries
- Available at: Online from UNICEF here. Also available via Gapminder here (search "vaccine" to find the data).