Who decides who should be vaccinated?
Countries set their own vaccine policies, and so these vary around the world, with some countries choosing to make certain vaccines mandatory.
Slovenia, for example, requires that all children are vaccinated against nine key diseases before they start school. Exemption is allowed only for medical reasons, and parents that don’t comply are fined.
On the other hand, a number of other European countries, as well as Australia and Canada, have no mandatory vaccinations. Here, parents or (if old enough) individuals themselves decide.
However, the governments of such countries may offer incentives to make sure that vaccination levels remain high. In Australia, for example, parents receive certain child benefits from the government only if their child has had all of its routine vaccinations.
Why don’t we have a vaccine for every infectious disease?
For some diseases, it’s a question of difficulty.
HIV, for instance, can insert itself into the genetic material of your cells and hide there undetected. Other viruses, like dengue, have multiple strains, which makes it very difficult to create a vaccine that covers them all. With other pathogens, the problem is mutation: continual morphing means that the immune system essentially encounters a new threat every single time, making past exposure count for nothing. This is why the common cold is so problematic.
For other diseases, it’s a question of process: there may already be several promising vaccine candidates in development, but rigorous safety and efficacy testing to make sure they work properly means that an actual approved vaccine is still years away. Developing a vaccine typically takes over a decade.
This is a particular problem with diseases that appear intermittently, as there’s limited scope for testing vaccines to fight them. This is why it’s really important to have vaccine candidates for emerging diseases ready for when outbreaks occur – so that they can be tested, approved and begin protecting people as quickly as possible, before an outbreak can harm too many people. Today we have a vaccine for Ebola only because candidates were ready to test at the beginning of the West African outbreak in 2014 – and even then we were too late to prevent over 11,000 deaths.
Finally, the absence of a vaccine may be down to economics. Vaccine development costs are often quoted in the billions, but many diseases without vaccines disproportionately affect low- and middle-income countries. Pharmaceutical companies have little incentive to invest in treatments that are unlikely to return a profit. This leads to diseases that predominantly affect the low-income world becoming neglected.
Why doesn’t everyone get vaccinated?
In theory, every person should receive every vaccine necessary to protect them from disease. However, not everyone may be able to be vaccinated, for various reasons.
People allergic to trace elements such as egg protein or pork gelatine have to avoid vaccines that are grown using these substances. And some people may be allergic to the antibiotics used in certain vaccines – this is why antibiotics known to often cause allergic reactions, such as penicillin, are generally not used in them.
Others may not be able to take certain vaccines due to pre-existing medical conditions, particularly those that affect the immune system, such as HIV/AIDS, cancer, having had a transplant or being on certain drugs.
But, there are also more contentious reasons. Religious and cultural beliefs lead some people to refuse vaccines, and there’s also hesitancy among some due to beliefs about vaccines being unsafe and/or unbeneficial.
However, the greatest barriers to full vaccine coverage are to do with delivery. One in five children across the world don’t receive their routine childhood immunisations, largely because of difficulties in getting vaccines to them. These children predominantly live in low-income countries.
This may be because of wars or natural disasters disrupting immunisation programmes, or it may be because these children live somewhere where it is difficult to get vaccines to them unspoiled. Vaccines contain biological matter, meaning they often need to be kept cool, which can be difficult in areas with intermittent electricity supplies.
Or, in some countries, it may be because providing all vaccines is too expensive. For the poorest countries in the world, Gavi, the Vaccine Alliance, provides funding assistance for immunisation. However, as its economy develops, a country must move from being financially supported to paying for vaccines itself. In this transitionary period, the costs of providing comprehensive vaccine coverage can sometimes be too great.
What is vaccine hesitancy?
Some people delay taking or refuse vaccines, either for themselves or their children, because they do not trust them. This is known as vaccine hesitancy.
Vaccine hesitancy is dangerous. It leaves individuals unprotected against diseases, and also lowers the overall rate of vaccination coverage, threatening herd protection.
Over the past decade or so, vaccine hesitancy has been rising, so much so that the WHO listed it as one of the top ten threats to world health in 2019.
What causes vaccine hesitancy?
Vaccine hesitancy is caused by mistrust, when people don’t trust vaccines’ safety or their effectiveness – or both.
According to the Wellcome Global Monitor – the world’s largest study into what people think and feel about science and health – globally only 79 per cent of people agree somewhat or strongly that vaccines are safe, with 7 per cent somewhat or strongly disagreeing. Another 11 per cent neither agree nor disagree, and 3 per cent don’t know.
The Global Monitor has shown that these levels of trust aren’t uniform across the world. People in high-income countries are less sure of vaccine safety. Only 72 per cent of people in Northern America and 73 per cent in Northern Europe agree that vaccines are safe. In Western Europe it’s is even lower, at 59 per cent, and in Eastern Europe it stands at only 40 per cent.
The opposite is true in low-income countries. The proportion of people who agree strongly or somewhat that vaccines are safe tends to sit at 80 per cent or above, with highs of 95 per cent in South Asia and 92 per cent in Eastern Africa.
We can’t say definitively what builds and erodes trust in vaccines. However, there is a correlation between trust and exposure to vaccine-preventable diseases. Where these diseases are endemic or their effects can be recently remembered, trust is higher. Conversely, where vaccines have removed the threat of disease and their effects aren’t immediately apparent, mistrust tends to appear.
Within regions, people who have high trust in doctors and nurses are consistently very likely to consider that vaccines are safe. Likewise, there is a clear positive relationship between overall trust in scientists and overall attitudes towards vaccines.
But there are also other, more complicated correlations – for example around education. In some places – like Northern Europe and Northern America – people with higher levels of science education are less likely to regard vaccines as unsafe. But in others – like Eastern Europe, Central Africa and Southern Africa – the opposite is true.
In certain places, we can hypothesise specific causes of mistrust. The long-debunked claims by Andrew Wakefield that the measles, mumps and rubella (MMR) vaccine was linked with autism are likely to be behind uptake of the vaccine falling in the UK.
And in Eastern Europe, where people are least likely to agree that vaccines are safe or effective, some researchers claim that vaccine scepticism may have been bolstered by Russian disinformation campaigns, which have amplified the vaccine debate on social media.