Measles and Vaccination

February 27, 2009 at 10:32 pm (Anti-Vaccination, Good Science) (, , , , , , , )

Today’s post looks at how serious measles is and what difference vaccination against measles has made.

How serious is measles?

Very. The Lay Science blog has covered this topic here. The post includes details of recent outbreaks of measles:

Italy, 2002: 4 deaths, 594 hospitalizations.
California, 1989/90: 75 deaths, 3,390 hospital admissions.
Japan, 2000: 88 deaths.
Germany, 2006: 160 children hospitalized, 3 with brain inflammation.
Ireland, 2000: 3 children dead, 350 hospitalized.

This “MMR the Facts” PDF has a list of the complications of measles and how frequently they are likely to occur:

ear infection (1 in 20)
pneumonia/bronchitis (1 in 25)
convulsion (1 in 200)
diarrhoea (1 in 6)
hospital admission (1 in 100)
meningitis/encephalitis (1 in 1,000)
late onset: SSPE* (1 in 8,000 children
under 2 years old)
death (1 in 2,500-5,000)

*Subacute sclerosing panencephalitis (SSPE) is a rare, degenerative neurological condition that can develop some years after natural measles infection and causes brain damage and death. The risk is greatest in those who were infected at a young age. The average interval from measles infection to onset of SSPE is around 8 years. Death invariably follows. Since the introduction of live attenuated measles vaccine in the 1960s, the incidence of SSPE has dramatically decreased and we expect the death rate from SSPE to fall even further. Measles vaccine directly protects against SSPE.

Convulsions, inflammation of the brain, and death seem to me to be pretty serious complications. In fact, in America, of the 501 measles cases reported during 2000-2007, one in four patients was hospitalized, and one in 250 died. This is referred to in the Lay Science blog post and the original source is this page.

How effective is vaccination against measles?

Both the single measles vaccine and MMR were successful in reducing measles notifications.

The single measles vaccine and MMR have both been successful in reducing measles notifications.

If you prefer numbers to graphs: HPA has some.

The 10 years prior to the introduction of the single measles vaccine (1958-1967) brought 863 deaths (and 4,120,936 notifications) and in the 10 years following the introduction (1968-1977) there were 292 deaths (a fall of 571 deaths – or 66%) – and 1,600,979 notifications (a fall of 2,519,957, or 61%).

The last 10 years of the single measles vaccine saw 837,424 notifications of measles and the first 10 years following the introduction of MMR saw 106,210 notifications of the disease. This is a fall of 731,214 (87%). Deaths in the 10 year period 1979-88 were 140, 10 year period 1989-98 were 18 – a fall of 87%.

So, deaths and notifications both fell about 60-65% following the introduction of the single measles jab in 1968 and deaths and notifications both fell a further 87% following the introduction of the MMR triple vaccine in 1988.

What happens if we reverse this trend? All we need to do is stop vaccinating our children and this is what we see – by 2003 MMR coverage was down to 82% (BBC report), which is represented by this graph:

MMR coverage down from a peak of 92% in 95-96 to 82% 02-03

MMR coverage down from a peak of 92% in '95-96 to 82% '02-03

Following the drop in MMR uptake, there was (unsurprisingly) an increase in cases of measles:

Vaccination goes down, measles cases go up...

Vaccination goes down, measles cases go up...

Hundreds died because of measles in the ten years prior to the introduction of MMR. Less than twenty died for this reason in the ten years following the introduction of this vaccine. As vaccination levels drop, measles notifications increase and the number of deaths inevitably increases. How many lives have these vaccines saved? How many people have been spared serious complications? How many people have avoided being infected with measles?

I’ll try to give an answer to the final of those three questions first: in the period from 1940 to 1968 (the year the single measles vaccine was introduced), there were 11,337,267 notifications of measles infection – a rate of 390,940 per year over the 29-year period. In the period following the introduction of the single measles vaccine and leading up to the introduction of the MMR vaccine, there were 2,326,316 notifications, a rate of 116,316 per year over the twenty year period. So it looks like the single measles vaccine may have prevented around five and a half million cases of measles in the period in which it was used (this is only hypothetical, but a reduction in the average number of cases per year of 277,624 over twenty years gives you 5,492,489). Five and a half million cases equates to 275,000 incidences of convulsions or 550,000 cases requiring hospitalisation according to the figures provided by MMR The Facts (1 in 200 and 1 in 100 respectively). The introduction of the MMR vaccine has seen an average of 109,429 fewer cases per year – over 19 years, that comes to about 2 million cases of measles (2,079,154 if my sums are correct). Again using the figures from MMR The Facts, this number of cases would equate to 100,000 incidences of convulsions and 200,000 cases requiring hospitalisation over the period of use so far. That’s an awful lot of people who avoided becoming seriously ill through measles infection and it looks like it is thanks to vaccination.

Deaths: there were 7,863 deaths in the period 1940-1968, with 5,687 occurring in the ’40s, 1,409 in the ’50s, and 767 from 1960-1968 (about 85 per year). Following the introduction of the single measles vaccine, deaths fell to about 20 per year (401 over twenty years of use). The introduction of MMR saw deaths fall still further to about 1.5 per year (27 over 9 years of use). From 85 deaths per year in the last nine years without vaccination down to 20 deaths per year in the twenty years we used single measles vaccine and then further down to 1.5 deaths per year – that means that (hypothetically) 1300 fewer people died during the period in which we used the single measles vaccine than otherwise would have done. A further reduction of 18.5 deaths per year over the nineteen years we have used the MMR vaccine equates to an extra 350 lives saved.

And finally

Some graphs were pinched from here, here and here. The media’s coverage of MMR, Andrew Wakefield’s approach to science, and the anti-vaccination movement have all been criticised on some of the blogs aggregated at badscienceblogs.net – e.g., this list of blogs covering MMR. The Bad Science blog itself has an archive containing 39 posts on MMR.

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6 Comments

  1. dvnutrix said,

    For the benefit of people who haven’t seen the Duisburg analysis of an outbreak in 2006, there are some sobering statistics that are a rather distressing of the story in the link that you give for Germany. As you highlight, measles has a high rate of complications: in this outbreak, it also had a mortality rate of 1 in 307 as 2 of the 3 young people with encephalitis died.

    The researchers interviewed patients/parents of cases in Duisberg district: 614 cases. The reported complications from these 614 cases were as follows:

    Otitis media (middle ear infection) 19%
    Pneumonia 7%
    Encephalitis 0.6%, (3 patients, 2 of whom died)
    Hospitalised 15%, median duration 6 days (range 2-97 days)

    Looking at infants:

    Otitis media 22%
    Pneumonia 17%
    The 2 children who developed encephalitis and died were aged 2 months and 2 years. The infant was too young for vaccination and would have relied upon herd immunity for protection.

    Overall, 13% of the children were too young to receive the vaccination.

    Of 464 patients for whom information was available, 373 (80%) were reported as unvaccinated, 62 (14%) as having received one MVCV dose and 29 (6%) as having received two doses. Seven patients or parents refused to answer this question, and 28 did not know the vaccination status.

    In addition to the above, the possible future toll of SSPE from that outbreak may remain unknown for some time.

  2. jdc325 said,

    Thanks for that dvnutrix. The mortality rate of 1 in 307 in Germany isn’t that far removed from that seen in the US from 2002-2007 (1 in 250). The figures from MMR The Facts do seem a little conservative in light of recent outbreaks. [Caveat: the number of cases involved are quite small in comparison with previous years - e.g., prior to vaccination. The UK figures for 1940, for example, had a mortality rate of 1 in 500 - which saw 857 deaths from measles in the UK. 1968 saw a rate of 1 in 5000 and a total of 51 deaths.]

  3. John Fryer said,

    How about developing a safer single vaccine using killed rather than live measles in the shots?

    By every expectation and from the data this disease should be like smallpox an illness that doesnt exist anymore.

    We need to use the full spectrum of health measures to combat this illness.

    The proliferation of vaccine given one at birth, 5 at 2 months, 5 at 4 months is causing some deflection from the aim of eliminating very serious illness whil vaccinating now for side effects of other vaccines.

  4. northerndoctor said,

    John, where to start?

    There is no evidence that a single vaccine is safer. It is a live attenuated vaccine and poses no risk to the child.

    The vaccine schedule you mention has no resemblance to the UK schedule. We don’t vaccinate at birth for a start. We do vaccinate at 2,3 and 4 months but there is no MMR until around 13 months.

    And how on earth are we ‘vaccinating now for side effects’??

  5. jdc325 said,

    Thanks for the comment Northern Doctor.

    I’ve seen John Fryer elsewhere make statements to the effect that mercury-containing vaccines are linked to 100,000 deaths in the US. Despite requests for references, he doesn’t seem to ever give them. Multiple vaccines seem to be another hobby horse of his. As does pointing out that he is a chemist [He signs his name elsewhere as "John Fryer MSc BSc Chemist"].

    Regarding multiple vaccinations, John seems to be an advocate of the “immune overload” hypothesis – a hypothesis that does not agree with the evidence. This page on the WHO website includes links to the Offit and Miller papers that show that:

    Current studies do not support the hypothesis that multiple vaccines overwhelm, weaken, or “use up” the immune system. On the contrary, young infants have an enormous capacity to respond to multiple vaccines, as well as to the many other challenges present in the environment. By providing protection against a number of bacterial and viral pathogens, vaccines prevent the “weakening” of the immune system and consequent secondary bacterial infections occasionally caused by natural infection.

    And:

    Combined measles, mumps, and rubella (MMR) vaccine did not increase the risk of hospitalisation with invasive bacterial infection in the three months after vaccination; rather there was a protective effect. These results provide no support for the concept of “immunological overload” induced by multiple antigen vaccinations, nor calls for single antigen vaccines.

    With regards the relative safety of MMR and the single measles vaccine, I would argue that it is actually safer to provide MMR – single vaccines have no advantage over MMR that I am aware of, and the MMR vaccine has the advantage that children are protected from all three diseases at once (rather than having a gap between vaccinations in which time they are left exposed to one or more of the diseases that MMR protects against).

  6. Measles - spot check from the HPA « Northern Doctor said,

    [...] Sadly, the headline ‘Measles Falling as Vaccination Works” won’t make the news and it won’t get blogged about much either. It is encouraging to see the rates come down but I will refer back to the Most Used Graph – it would be much more reassuring to get back to pre-2006 rates and the risks are still very real. [...]

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