Vaccines help prevent infectious diseases. It is important that most people get vaccines and if enough people are vaccinated, protection is also given to people who have not been vaccinated. This is known as herd immunity. Even though most children do get the vaccines they are offered, there are still some areas in the UK where there have been outbreaks of disease.

In general, parents in the UK need to give permission for children under the age of sixteen to have a vaccination. Whilst many parents choose for their children to be vaccinated, some parents decide not to. It is important for us to understand why parents might decide not to vaccinate their children, so that we can address any issues that might be stopping parents from vaccinating. Only once we understand the reasons for non-vaccination can we start to think of ways to tackle them, to try and increase uptake of childhood vaccinations. The best way for us to find out what these issues might be is to review existing research in this field, much of which has been qualitative. Qualitative research aims to understand a topic by finding out people’s opinions, attitudes, motivations etc. This is often done by conducting interviews or focus groups.

In our review, published this week, we aimed to do just this; to look at qualitative studies in the UK that had looked at vaccines for children, to try to understand what might influence parents’ decisions about vaccination. We reviewed a total of 34 studies. The results of each of these studies were then re-analysed to find common themes between them.

We found that parents make decisions about vaccination in two different ways: some made decisions automatically, and others made more intentional decisions.

Automatic decisions

Automatic decisions are decisions that are made by parents without too much thought. When parents made these types of decisions they were often happy to go along with the advice about vaccination that was being given to them from health professionals. Parents also made automatic decisions when they did not feel like they had a choice and/or when they were copying the decisions other people had made about vaccinating their children. These types of decisions are often made quickly and parents did not appear to weigh up the pros and cons of vaccination when making them.

Intentional decisions

Intentional decisions are decisions that parents have taken more time to think about. When parents made these types of decisions they often weighed up what they perceived to be the risks and benefits of vaccinating and often judged how appropriate it was to vaccinate their child based on other people’s advice or experiences. Many parents making intentional decisions felt responsible and/or were worried about being judged by other parents for the decision they were making. Parents’ emotions had an effect when making intentional decisions, as did the media and what was being reported about vaccination.

Additional factors

The media affected the trust that parents had in information they received about vaccination, and in medical professionals, the government and the NHS. Trust (or a lack of trust) was important for parents when making both automatic and intentional decisions. Practical issues, for example travelling to the vaccination clinic, having a lack of time or being unable to get an appointment, also affected the decisions of parents who had decided to vaccinate, regardless of whether they had made an automatic or intentional decision.

What does this tell us?

Many parents who made automatic decisions had decided to vaccinate their child. However, some of these parents had decided to vaccinate because they felt pressured to do so. Other parents had copied other people and not vaccinated their child. Some parents who made intentional decisions had involved others in their decision-making, by speaking to family members, friends or work colleagues.

The findings of this review highlight how important social factors are for parents when making decisions about vaccinating their child. The impact of one child not having a vaccination may go beyond just that child being unprotected, as that decision may influence other parents’ decisions. By understanding more about the decisions parents make about vaccinating their children we will be in a better position to start to think of things we can do to encourage more parents to give permission for their children to have childhood vaccinations.

As mentioned in one of our previous blog posts, talking about genes in the context of obesity is often not well received.  Those discounting their role in the development of obesity often argue that, because genes have not substantially changed over the past 200 000 years, whereas obesity levels have only been soaring over the past 20 odd years (where it became possible to mass-produce cheap, tasty food in combination with a decreased need for physical activity), obesity must be due to changes in the environment, and not genetics.

However, using this argument against the heritability of obesity is somewhat flawed, because it ignores that a condition can be dormant over a period of time until the right circumstances bring it to life.  The gardeners among you will know that many plants will adjust their growth according to their surroundings – a plant in a small pot will remain small, whereas a larger pot will allow it to grow.   This, however, does not mean that the plant loses its ability to grow larger in a smaller pot; it merely remains small because its surroundings restrict its growth.  Similarly, genes predisposing to obesity may be present in an environment where little food is available, but without the right ‘medium’ (i.e. food), this is of little consequence.  In the current environment, however, where eating opportunities are plentiful, obesity genes can express their full force.

If obesity was resulting purely from environmental change, all individuals exposed to this change would become overweight.  Yet, this is not the case. In fact, the proportion of lean people has not substantially changed, but large people are becoming even larger.  This suggests that people respond to the food environment differently.  However, undoubtedly, to gain more weight than is healthy, food must not only be available in sufficient quantities, but one must ingest more of it than necessary.  Therefore, researchers started to look at differences in eating behaviours, such as how much we are drawn to food and how quickly we feel full, to see what is going on.

Twins can help to untangle the influence of genes and environment on obesity, because identical twins are 100% genetically identical, whereas non-identical twins only share approximately half of their genes (like normal siblings); both, however, grow up in a very similar environment.  This means that researchers can compare identical twins’ resemblance for weight with that of non-identical twins; if genetically identical twins are more similar in a trait than non-identical twins, it is evidence for genes being responsible for the trait.

Using twins, researchers from our department wanted to see whether genes that influence weight also influence appetite.  If the same genes that influence weight also influence appetite, it suggests that genes influence weight through their effects on appetite – i.e. individuals who inherit more avid appetites might be more susceptible to overeating in the modern food environment, and consequently  more likely to gain excessive weight.  They looked at this in infants, because infants are exclusively milk-fed, which ruled out that other factors such as preference for certain foods would influence the results.   The researchers used questionnaires to ask parents about how fast their twins fed, how easily they got full and how big their appetite was, and related the answers to the babies’ weight.   Because they used a sample of identical and non-identical twins the researchers were able to explore the extent to which appetite is heritable, and the extent to which appetite and weight are caused by the same genes.

They found that identical twins were not only very similar in weight, but shared many more similarities in appetite than non-identical twins, suggesting a strong genetic basis to both appetite and weight.  In addition, the results  showed that a substantial proportion of the genes that are responsible for weight are also responsible for appetite, in line with the idea that genes influence weight through appetite.  These findings lend evidence to the idea that some of us are more likely to overeat in the current environment because of a larger appetite, which is ultimately driven by genes.

These discoveries will hopefully contribute to reducing the stigma that surrounds unhealthy weight gain; because it clearly shows that those struggling with weight are in a sense ‘battling against their biology’.  This of course, does not mean that there is nothing that can be done about it; however, acknowledging these differences as real and designing strategies to ‘outsmart’ one’s genes is crucial if the battle is to be fought successfully.

Article reference: http://www.ajcn.org/content/95/3/633.long