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more on measles

If you've seen today's papers (& I guess it's on TV/radio as well), you'll know that the outbreak of measles that began in Christchurch seems to have spread to Auckland (by the simple path of someone picking up the infection in Christchurch & then travelling north, I suspect). A measles expert quoted on the Science Media Centre site (I'll post the interview below) commented that this can probably be put down to lower-than-desirable vaccination rates, & that in some ways vaccination has been a victim of its own success: complications due to once-widespread diseases are now so rare that a generation of people has forgotten what they were like & why they were so serious.

This resonated with me. My mother had polio as a young woman in the 1930s. It left her with much smaller & weaker muscles in her right hand & right calf (her arm & leg were most affected by the illness.) And a very close friend spent months in an iron lung in the 1950s, completely paralysed by the virus & relying on the 'lung' to maintain her breathing. But these days the odds of meeting someone affected are really pretty small, due to the effectiveness of the modern vaccine - & so we tend to forget how bad the illness actually was. The same can be said of diptheria, whooping cough & yes, measles - while many children may escape with a mild infection, this is not a trivial disease.

That's one reason we vaccinate. But some individuals can't be vaccinated - those who are immuno-compromised, for example, or the very young. And they therefore rely on something called 'herd immunity' to reduce the odds of their catching a life-threatening illness. Once vaccination rates drop below a given level, herd immunity begins to break down & rates of infection increase.

Anyway, here (from the Science Media site) is the interview.

In response to questions posed by the SMC, Dr Katz [replies]:

What do you believe explains the relatively low level of immunisation in some western countries such as New Zealand and what are the consequences if the rate of immunisation for measles isn't improved?

"Because in most countries who can afford vaccine programs many of the formerly common childhood infections no longer cause major outbreaks, young parents as well as health care workers are often unfamiliar with the morbidity and mortality that may result from them.

"Measles vaccine has been available for more than 45 years and in those countries where it has been widely accepted and used, measles is almost  an invisible disease.

"Instead of 3 or 4 million cases a year (20% of whom were hospitalized with complications, most often pneumonia or gastroenteritis) prior to vaccine, we have had fewer than 100 cases per year over the past decade in the U.S. Those few cases almost all result from importations. This is true throughout the western hemisphere In the absence of universal immunisation, an importation can lead to a cluster of cases or an outbreak among the unvaccinated. Measles is the most highly transmissible of the vaccine-preventable infectious diseases.

What does the latest research say about the safety and effectiveness of vaccination for measles? Is there any scientific basis for parents not vaccinating their children?

"Measles vaccine is both safe and effective. Repeated studies in Europe and North America have totally disproven the claim that MMR led to autism and bowel disturbances. As with any biological item, there are unusual adverse reactions (allergic, hematologic, neurologic) but these are extraordinarily rare."

As one of the scientists who came up with the measles vaccine, how do you feel about parents refusing the vaccine for their children in wealthy Western countries when children in the developing world still have limited access to vaccination?

"We are participating in a campaign called the
Measles Initiative to reduce the death toll of measles in the resource-poor nations of sub-Saharan Africa and Southeast Asia. Prior to vaccine, WHO estimated there were 6 million deaths annually from measles. As recently as 10 years ago this had been reduced to about 1 million with the use of vaccine.

"However, even that was intolerable so the program was started in 2001 to bring vaccine to as many of these children as possible,  and has successfully reduced deaths to about 200,000 per year.

"The virus is the same as that encountered throughout the world, but these children suffer from malaria, malnutrition, HIV and/or intestinal parasites so that measle infection pushes them over the brink. Children in "wealthy" nations do not suffer that sort of mortality (1 per 500 measles cases rather than 5-10% of them) but 20% end up in hospital and some of them may be left with enduring sequelae (pulmonary, neurologic, hearing, visual)."

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2 Comments

This is surprisingly topical for me, as my (one-year old) daughter had her first MMR vaccination today. It was probably as painful for me as it was for her - ah the never ending guilt of parenthood!

But I really don't understand the reluctance of people to immunise their children when often the possible complications from the disease are worse than the supposedly possible complications from the vaccine. I guess it shows how susceptible people are to media hype and half-truths, rather than taking the time to research topics thoroughly themselves.

Part of the problem may be that vaccination is a victim of its own success - diseases that regularly killed or permanently injured children of my parents' generation simply aren't seen these days, or if they are, they're rare. So as that older generation disappears, & their children in turn age & die, we're losing that intergenerational 'memory' of what those diseases were really like.

On the 'vaccines cause [insert name of 'problem' here] - we do tend to look around for something or someone to blame for our misfortunes. Perhaps it's easier to blame a vaccine (especially where the disease itself is relatively unknown) rather than accept that we may never know the cause of the problem or - for, say, autism - than it is to accept that there may be a genetic component & hence we are ourselves implicated in some way.

While I think of it, that lack of intergenerational memory doesn't stop with childhood diseases. I having lunch with a volcanologist yesterday & he remarked that people have a remarkable ability to forget disasters like major eruptions. Following such an event, people may disappear from a volcano's slopes & surrounds in the short term, but given time they'll be back...

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