It's foolish and dangerous to avoid vaccines

PHOTO: It's foolish and dangerous to avoid vaccines

SINGAPORE - Parents in Singapore don't worry too much about diseases that vaccines prevent, like measles, which was well on its way to being eradicated from the world.

The World Health Organisation (WHO) reported a 78 per cent drop in deaths from measles worldwide between 2000 and 2012. This was in large part due to progress in Africa, India and other developing regions.

In developed nations, however, progress has been stymied by the rise of "vaccine denialism". As a result of fraudulent research linking the MMR (Measles, Mumps & Rubella) vaccine to autism, some parents in the West now refuse to have their children vaccinated.

Denialism has now spread to the educated class in many countries, including Singapore, if online discussion is any indication.

Vaccine denialism translates into utterly preventable deaths. Earlier this year, a young man in Wales and a teenage girl in the Netherlands, both not vaccinated, died of measles. Last year, there were 2,000 measles cases in Britain, the most in 19 years; and 175 cases in the United States, the most in 17 years.

Meanwhile, there has been a major measles outbreak in the Philippines, with 2,417 cases last year. Since January this year, 23 Singaporeans who travelled to the country have come back infected. Cases from the Philippines have also turned up in Australia, Britain, Canada, Japan, New Zealand and the US recently.

So far, 80 people in Singapore have come down with measles this year - half of whom had not been vaccinated - a great rise against the 40 cases in 2012 and 31 cases last year.

Parents may remember measles as just a fever and rash. Mainly a respiratory infection, it kills one or two out of 1,000 cases.

The gravest complication is encephalitis, which afflicts one in 1,000 cases. Here, the brain is inflamed and swollen, so the patient has severe headaches, clouded thinking, fits, and problems with movement. If the brain swells enough, the skull basically crushes the organ, leading to death in 15 per cent of measles encephalitis.

Some 20 to 40 per cent of those who survive measles encephalitis suffer neurological deficits for life, like deafness, blindness or mental retardation.

Crucially, a minority of those infected before they are one year old will develop in childhood and adolescence - but even up to 27 years afterwards - an incurable condition. This is subacute sclerosing panencephalitis (SSPE), in which the child seems to recover fully from measles. But because its immune system reacts abnormally to the virus, brain and spinal cord nerve cells are perpetually swollen, so they gradually break down.

This degenerative brain disorder is fatal, usually within a year or two after diagnosis.

The patient develops abnormal behaviour, muscle spasms, unsteady gait and fits, as well as suffers from memory loss, impaired speech and so on.

British studies suggest that 18 of every 100,000 babies infected under age one will develop SSPE but only 1.1 per 100,000 of those infected after age five do so.

The more cases of childhood measles, the more likely there will be cases of encephalitis and SSPE. In contrast, the risks with the vaccine are negligible: fever, a mild rash, one in 3,000 risk of fits, and one in 30,000 chance of developing a bleeding tendency for a little while. But there is no deafness, encephalitis or SSPE with MMR.

Prior to 1963, when the US licensed the first measles vaccine, almost every child had measles by age 15. By 1968, there were almost no measles cases in the US. Singapore mandated the vaccine from 1985.

As the vaccine was first tested in 1958, anyone born in or before 1957 is assumed to have had measles and thus immune. No one else is immune unless vaccinated and all it takes is one child on a flight from Manila or London, say, for an outbreak to start. So MMR is reasonable insurance.

MMR denialism began in Britain with fear-mongering by Andrew Wakefield, a doctor now struck off the British medical register for his 1998 study, a fraudulent case series linking MMR to autism. It was published in the top medical journal, The Lancet.

None of his cases tallied with the actual patient case notes. The British Medical Journal engaged an investigative journalist to detail Wakefield's plan to enrich himself by discrediting MMR and have a lawyer sue vaccine makers.

Because the British media sensationalised Wakefield's claims, many parents were taken in, leading to plummeting vaccination rates. In certain regions of the country, these fell to 50 per cent. Measles, considered already conquered in Britain, became endemic again in under a decade.

Likewise in Europe that has, in recent years, even exported cases to other countries, including Africa.

To prevent measles outbreaks, 90 per cent to 95 per cent of the population must be vaccinated. (The rates in Singapore have been consistently above 95 per cent so we may still be safe - for now.)

When enough numbers in a community are vaccinated, the non-immune are less likely to become infected because the bug cannot thrive out there. These non-immune cases are those who cannot be vaccinated because of their compromised immune status; those in whom MMR never took; kids whose parents forgot to get them the shots; and, kids of denialists.

Denialists put all children at risk since vaccines are never 100 per cent effective. In general, up to 10 per cent of vaccinated kids may be non-immune.

But since at least 90 per cent of the population must be immune for this "herd immunity" to work, even a modest fall in vaccination rates may put all kids at risk.

This is why despite the high vaccination rates in Singapore (required for school enrolment), outbreaks can still occur.

The WHO reports that field investigations of recent measles outbreaks confirm that most cases involved non-vaccinated persons.

The more contagious the disease, the higher the percentage of vaccinated is required to protect the non-immune - and measles is one of the most contagious viruses ever. But now there are wilful non-vaccinators, including expatriates, in our midst who are creating pockets of the non-immune.

In the West, even where it is mandated, exemptions may be permitted by the authorities, like school districts, for what are called "philosophical objections" to vaccines. These denialists are generally educated, affluent parents whose Google research has transmuted them into experts on vaccine risks.

They ignore the multiple well-designed studies that have repeatedly shown, at great costs in time, effort and money for over over a decade now, that MMR is safe and not linked to autism.

How to stop more parents from becoming denialists? Only aggressive public education can do so, which may need to be undertaken with some urgency.

andyho@sph.com.sg

Get a copy of The Straits Times or go to straitstimes.com for more stories.