Mr Cary, perhaps you should be putting more effort into rescuing a fast-dying faith following than crying for continued privilege in a modern society.

I’ve always found it extraordinary to consider that in a sin-fearing culture the unrighteous might breed as they chose but the supposedly Godly should fail to be permitted to rear another generation who might be supposed to be brought up in a righteous fashion [well we've seen the strangleholds some religions have on their children but it still seems a good idea in theory....]

Just remember, celibacy is not hereditary.

You question whether people who are (for example) immunocompromised are at more risk from the vaccine or the disease. I think it’s a bit more complicated than that.

There are broadly two types of vaccines: live vaccines, which contain a very weak form of the target pathogen, and non-live vaccines, which contain dead fragments of the target pathogen. Examples of live vaccines include MMR, FluMist (nasal) and the old oral polio vaccine. Most other vaccines are non-live.

Patients can have compromised immune systems as a result of genetic conditions (eg. primary immune deficiencies such as neutropenia, common variable immune deficiency, severe combined immune deficiency and more), as a symptom of another condition (eg. HIV, radiation poisoning, some forms of leukaemia) or as a side-effect from another therapy (eg. in response to many forms of cancer therapy which kill off fast-growing cells such as those found in the immune system.).

Patients with a compromised immune system absolutely should not have a live vaccine. This is because there is a risk that such patients will develop the actual disease; there are documented cases of this, including an outbreak of oral polio in a secluded religious community in which a large number of children had a primary immune problem.

Another reason not to give people a particular vaccine is that they have an established allergic response to an ingredient; a common example I hens eggs.

Non-live vaccines can (normally) be given to immune deficient patients. In some this will confer protection, in others it will not. Regardless, it’s a passive injection unlikely to cause harm. For example, I (who have common variable immunodeficiency) always have the seasonal flu jab, but we don’t know if it confers any protection.

It’s also worth noting that immune systems are so genetically variable that even healthy people with “normal” immune systems may not develop immunity in response to a particular vaccine.

However, for a vaccination program to be effective, not every individual in a community needs to be effectively immunised against a particular pathogen, regardless of the reason. If a person who is unprotected is surrounded by people who are immune, then the pathogen cannot be passed on to them. This is herd immunity, and it can be thought of as a biological insulation of vulnerable individuals.

For herd immunity to be effective, however, a very high percentage of the population must be inoculated. The more infectious and virulent the disease the greater the percentage required for effective protection. Whooping cough requires more than 90% coverage; mumps around 75-86%.

So in response to your second point: the issue from my perspective isn’t whether or not we should put immune deficient people at risk through giving them live vaccines, but whether we should allow them to be put at risk by people not vaccinating their children. From my perspective, it’s immoral to decide not to vaccinate children when it put me at greater risk than the child.

In response to your first point, vaccination monitoring is a key task in public health, and statutory agencies (HPA in the UK at the moment, shortly to become local authority public health teams; CDC in the USA) use various intelligence systems to identify when there is an association between a vaccine and a syndrome or a particular disease.

Unfortunately, these monitoring systems can be subject to false positives and are often indeterminate. For example, there was a question as to whether Guillaine-Barré disease (a neurological condition) was associated with a vaccination program in the USA in the mid twentieth-century. Although there was a correlation, evidence of a definitive cause was lacking.

If the immune system was “overloaded”, this would definitely be picked up on by these monitoring systems. The sample sizes (>60 million people in the UK alone over the last 50 or so years) would result in a strong signal being identified.

It’s also worth noting that “overload” is a fairly emotive term that has no real meaning in immunology: we get exposed to thousands of bacteria and viruses every day from the day we’re born. It’s difficult to see how vaccines would result in a different effect.

Finally, government have certainly handled vaccine problems badly in the past; it handled pertussis vaccination so badly in the UK that rates dropped to ~30% in the 1970s, resulting in three whooping cough epidemics in the year I was born (1977).

However, monitoring is now handled by independent professionals (in the UK), and vaccine companies are much more accountable and visible than they used to be. Whilst government sets policy, it’s professionals who determine which strains are likely to be high risk.

Unless you are willing to suggest a massive conspiracy involving thousands of people – in which case there is little or no point trying to debate the issue – it’s very unlikely that such a case would remain secret. That’s not to say that government responses to public health problems couldn’t improve (see the horse meat kerfuffle!), but that keeping it a secret would be a challenge.

However one looks at it, immunisation is an emotive issue. For vulnerable people (and their parents) there’s the concern that someone at work or in their class might be putting them at risks; for parents deciding whether or not to vaccinate, there’s the concern that regardless of statements of safety by experts whether one’s child might be one who is affected. Where does the balance lie?

The balance lies in seeking to protect the interests of both. There is no such thing as a zero-risk vaccine any more than there is a zero-risk form of transport. We can’t invoke the precautionary principle because the consequences of not vaccinating (millions of unnecessary deaths) overwhelm any potential objections. Ultimately, it is a decision that has to be made as an informed, conscientious individual. For me, the danger lies in the sheer volume of misinformation which is promulgated by some very unsavoury characters who, far from fighting massive corporate interests to protect the defenceless citizen, are often empowering a different and less accountable and regulated set of big companies. At least if you decide not to vaccinate, ensure the decision isn’t based on known untruths.

I’m not suggesting I don’t enjoy these things, merely that they are the cultural equivalent of McDonald’s