health & science
Measles: as certain as death and taxes
Catching the highly-infectious measles virus during an outbreak used to be as certain as death and taxes. Now a vaccine is 97 percent effective against the disease. In the third in a series on vaccines and the diseases they prevent, Farah Hancock reports on the measles, mumps and rubella vaccine, its rollercoaster ride through public opinion and looks at where in New Zealand vaccine coverage is below the target.
The man who has saved more lives in the 20th century than any other medical scientist started his career in a Montana department store in 1937, helping “cowpokes” pick out chenille bathrobes for their girlfriends.
After prompting from his brother, and with a personality not suited to customer service, Maurice Hilleman gave up retail in favour of study. He turned his hands and mind from bathrobes to microbiology.
Few people know his name yet during his career, and in an era where being a child was perilous, he developed 40 vaccines, several of which are still used today. It’s estimated his work saves millions of lives every year.
Quick-tempered and with the vocabulary of a sailor, Hilleman described himself as a renegade.
As a child he got in trouble for reading Charles Darwin’s Origin of Species in church and suggesting a pastor get his stomach pumped to prove the claim sacramental wine turns into Christ’s blood.
Despite his renegade nature he ran his laboratory like a military operation, inspiring loyalty from his team and producing a prolific output of vaccines.
He was described as a genius when it came to coaxing a vaccine to achieve the balance of effectiveness without infection and with minimal side effects.
However, when he died in 2005, he was dismayed at the resurgence of some of the diseases he spent his life trying to prevent. His measles, mumps and rubella (MMR) vaccine was accused of causing autism. Instead of recognition for a life’s work spent making the world safer for children, he received hate mail.
Vindication came too late. Five years after Hilleman’s death the doctor responsible for the fraudulent study linking autism and Hilleman’s vaccine was stripped of his title and the study was retracted by the journal which published it.
Hilleman described his life as being devoted to “the quest of science and winning a battle over these damn bugs”.
Measles versus Ebola
Ask people what the scariest virus is and many will answer Ebola.
There’s no denying Ebola is terrifying, and the sight of doctors and nurses clad in hazmat suits only highlights its infectivity. Surprisingly though, measles leaves Ebola’s infection rates in the dust.
A person with Ebola will typically transmit the virus to 1.5 to 2.5 other people. A person with measles is likely to infect 12 to 18 people.
If you’re not vaccinated and haven’t had measles before, there’s a 90 percent chance if you come in contact with an infected person, you'll get the virus.
Measles doesn’t have the same fatality rate as Ebola's 50 percent, but because of its infectiousness it has killed more people than Ebola has, and is the leading killer among vaccine-preventable diseases.
The University of Auckland's Dr Helen Petousis-Harris describes measles as “an insidious little thing”.
The first thing the virus generally comes in contact with is lung tissue. Infected cells migrate to lymph nodes. Here they transfer to B and T cells.
The B and T cells then travel through the body releasing virus particles along their way and infecting lymph nodes, the spleen, liver, thymus, skin and lungs.
About 30 percent of people who get measles have one or more complications on top of the cough, fever and rash normally experienced.
These can include diarrhoea, ear infections, pneumonia, encephalitis, seizures and death. Children are most likely to die from pneumonia and adults from encephalitis.
In one in 1000 cases the virus crosses to the brain and causes swelling. If this occurs there’s a 15 percent chance of dying. An infection in the brain can cause convulsions, brain damage and permanent hearing loss.
There can also be long-term effects.
Subacute sclerosing panencephalitis (SSPE) is a rare, fatal disease of the central nervous system which can occur seven to 10 years after a person catches measles. Death occurs one to three years after the first symptoms of SSPE are noticed. Mood swings progress to uncontrolled jerking movements, then coma and death. There is no cure for SSPE.
Petousis-Harris said measles can also hijack your immune system.
“It actually has a whole lot of consequences I think people don't think about. There's been this idea for, for a long time that, that having a disease like measles strengthens your immune system. It does the opposite.”
A recent study also showed measles may also cause “immunity amnesia”. The damage the measles virus does to the immune system can have a two to three-year effect, leaving the measles sufferer vulnerable to other infectious diseases.
The study showed children who had measles were more likely to die from other infectious diseases.
Three diseases, one vaccine.
Vaccines work by exposing a person to just enough of a virus for the body to create antibodies, but not get sick. If the person comes across the virus their body already has the tools to fight it.
The first measles vaccine was created in 1963 by John Enders. It worked, but side effects such as rashes and fevers were common.
Hilleman worked to create a vaccine which didn’t have the same side effects. At the same time rubella was sweeping through the world.
In an effort to increase vaccination rates against measles, mumps and rubella, Hilleman created the combined MMR vaccine in 1971. It included his measles and mumps vaccine and initially it included a rubella vaccine he created. He later changed this in 1978 to a more effective rubella vaccine developed by Dr Stanley Plotkin.
Gaining immunity to the three viruses used to require 12 injections, the combined MMR vaccine meant just two injections were needed. This increased the chances of more children being protected against more viruses.
A common fear of parents is that the effect of giving their child three viruses at once to create antibodies could be over-whelming for their young bodies.
Petousis-Harris said what parents may think of as an onslaught on a child’s body, is actually child’s play for the immune system, which can respond to trillions of things at once.
“Your capacity to respond to lots of things at once is vast.”
She gives the analogy of birth to show the body’s capability of dealing with multiple things.
“At birth an infant has exposed just with the faecal flora from the mother to about 400 different types of bacteria and other microbes.”
Three weakened viruses at the same time pose no challenge, according to Petousis-Harris, who said a child's body can deal with them “without blinking”.
Wakefield’s body count
With the price of the MMR vaccine as low as $1 to $2 a dose, there’s a real chance measles could be eradicated from the world, however, the cases of measles in some countries has seen a sharp increase.
In 1998 Andrew Wakefield published a paper linking the MMR vaccine with autism. It was published in The Lancet.
His findings were seized upon by media and parents of children with autism. Wakefield made several public appearances recommending a single measles vaccine, rather than a combined vaccine.
However, all was not as it seemed. The study came under fire for several reasons. Wakefield had accepted a large amount of money prior to the study from a lawyer who wanted evidence for a court case against vaccine makers. Wakefield also had a patent for a single measles vaccine lodged. None of these conflicts of interest were declared in his study.
University of Otago associate professor Dr Andrew Moore specialises in ethics. He said there are a number of troubles with Wakefield’s study.
“It's important for a researcher to declare if they have a financial or any other interest in one rather than another answer to the study question you are answering.”
Moore said there was a significant conflict of interest in the study.
“If you're dealing with people in a way that could have big implications, potentially harmful ones for people and you've got more axes to grind and the one that is being presented up front, it's very important to declare that, not just assume that you've got ethical brilliance to manage it all yourself.”
Even if the conflict of interest had been declared Moore is skeptical of the study.
“The design for example of the study is not the kind of design that has any chance of answering a big question, like whether vaccination causes autism. There's a fundamental trouble with it right there.”
It was also found the medical histories of the 12 children involved in the story were misreported.
In 2010, Wakefield was struck off the medical register and The Lancet retracted the paper.
But by then, the damage had been done. Parents had linked vaccines with autism and chosen not to vaccinate their children. In parts of the United Kingdom vaccination rates which had previously been between 92 to 95 percent, plummeted to between 60 and 80 percent.
Petousis-Harris sums up the legacy of Wakefield’s study bluntly: “The legacy is a body count.”
“I think for a long time a lot of countries saw declines in their coverage and then that recovered.
“Then social media came onto the scene and Andrew Wakefield made a movie, Vaxxed and that has driven a renaissance of the zombie meme that MMR causes autism.”
Several studies since Wakefield’s have failed to find any link between the MMR vaccine and autism. The most recent surveyed 500,000 children. No link was found.
How is New Zealand doing?
Measles was eliminated from New Zealand in 2017. Outbreaks which occur are due to people who contracted measles overseas bringing it into New Zealand. There are 47 confirmed cases in the current outbreak, which is mainly centred in Christchurch.
If enough people are vaccinated, outbreaks are small, and the virus fails to spread. When vaccination is low, the virus can spread through the community.
Ideally, between 92 and 95 percent of the population needs to be vaccinated to achieve “herd immunity” which is where so many people are immune to a virus there's a lower chance those who can't be vaccinated, like babies, are exposed to it. Full vaccination for measles requires two injections, one at 15 months old, and one at four years old.
As of December 2017, 92.4 percent of infants had received their first dose of the MMR vaccine, but only 88.6 percent of five-year-olds had received their second.
Statistics from the Ministry of Health for District Health Boards show data by birth cohort from 2006 to 2012.
The West Coast, Bay of Plenty, Northland and Nelson Marlborough all have rates below 90 percent for children born between 2006 and 2012.
Inequalities exist between ethnicities. While Māori children have a higher vaccination rate than European children for their first dose of the vaccine, this drops for the second dose.
A Progress Towards Measles and Rubella Elimination in New Zealand document prepared by the Ministry of Health lists the national response to outbreaks. They include public communication to get vaccinated, but note there is no long-term strategy: "No funding has been available nationally to support supplementary immunisation activities to increase immunity against measles. However, further potential strategies are still being considered.”
The document notes there is a need to find and immunise the “significant pockets of susceptible individuals”. It estimates coverage in people born after 1980 and before the 2005 National Immunisation Register was created could be as low as 75 to 85 percent.
The concern about vaccination hesitancy, one of the World Health Organisation’s top 10 threats for 2019, has led The New Zealand’s Skeptics to start a fundraising campaign for a film competition. Children will be challenged to make their own film demonstrating the importance of vaccines, with the winner receiving $5000.
NZ Skeptics chair Craig Shearer said: “Children get taught the science of vaccines at school, but we think that creating a video, with the research and learning involved in that, will sow the seeds of critical thinking so important in countering vaccine misinformation."
Overseas unvaccinated children have been waiting until they reach an age of legal consent before getting vaccinated against their parents' wishes.
Before his death, Hilleman talked with long-time friend and doctor Paul Offit. In the documentary Hilleman: A Perilous Quest to Save the World's Children Offit recounts the conversation:
“I asked ‘Couldn’t there be some way to educate the public about the importance of these vaccines without having to watch what we are watching now?' Which was children suffering and dying again from these diseases?’
He [Hilleman] paused for a long time, then looked back at me and said, ‘No. I think the only way we actually are going to get people to understand the importance of these vaccines is to watch children suffer again’. Then he turned his back to me and looked again outside.”
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