Tag: measles outbreaks

Measles Vaccines vs Measles Strains

Most people understand that for every virus or bacteria, their can be multiple strains of the same organism that cause disease.

For example, there is flu A and B, swine flu, bird flu, and even dog flu.

In the case of flu, those different strains are a problem, because having immunity to one, doesn’t mean that you will have immunity to others. In fact, usually you won’t, whether it is natural immunity from a previous infection or immunity from a vaccine.

Pains with Strains

Do we have the same issues with other diseases?

We certainly have situations in which vaccines don’t cover all disease strains, including:

  • Gardasil – now covers nine strains of HPV that cause 90% of cervical cancers
  • Hib – only covers Haemophilus influenzae type b, which causes invasive disease, like meningitis, pneumonia, and sepsis, but not other Haemophilus influenzae strains that can cause ear infections
  • Polio – originally protected against three serotypes of polio, but monovalent (one strain) and bivalent (two strains) oral poliovirus vaccines have also been available to respond to outbreaks and bOPV is the one used for routine immunization, except in industrialized, polio-free countries that use the IPV shot
  • Prevnar – now covers 13 strains of Streptococcus pneumonia
  • Rotavirus – protects against severe disease caused by rotavirus strains that aren’t even in the vaccine

Fortunately, even when a vaccine doesn’t cover all strains, it does cover those that most commonly cause disease.

Measles Genotypes

Knowing the genotype of a measles strain can help you understand where measles outbreaks are coming from.
Knowing the genotype of a measles strain can help you understand where measles outbreaks are coming from.

What about measles?

There are at least 24 different genotypes of measles that come from 8 different clades (A-H), with even more wild type virus strains (based on those genotype).

These genotypes include A (all vaccine strains are genotype A), B2, B3, C1, C2, D2, D3, D4, D5, D6, D7, D8, D9, D10, D11, G2, G3, H1, and H2.

In general, genotypes are restricted to a specific part of the world, such as:

  • African Region – B2, B3
  • Eastern Mediterranean Region – B3, D4, D8
  • European Region – D4, D5, D6
  • Southeast Asian Region – D4, D5, D8, D9, G2, G3, H1
  • Western Pacific Region – D5, D9, G3, H1

In countries that have eliminated measles, like the United States, the genotypes that are found will depend on from where the measles strain was imported.

Additionally, five genotypes, B1, D1, E, F, and G1 are now inactive.

Measles Strains

Specific strains of measles viruses include the vaccine strains (Edmonston, Moraten, Zagreb, Schwarz, AIK‐C, CAM, Leningrad-16, and Shanghai-191, etc.) plus wild strains, like:

  • MVi/NewYork.USA/94 – a wild strain of B3 genotype
  • Johannesburg.SOA/88/1 – a wild strain of D2 genotype
  • Manchester.UNK/30.94  – a wild strain of D8 genotype
  • Hunan.CHN/93/7 – a wild strain of H1 genotype

Why so many vaccine strains?

It may come as a surprise to some people, but the whole world doesn’t use the same vaccines. For example, unlike the United States, Japan has used measles vaccines derived from AIK‐C, CAM, and Schwarz strains of the measles virus.

And just how many wild strains of measles are there? It’s hard to know, but consider that a study of 526 suspected measles cases from 15 outbreaks over 3 years in one state of India found at least 38 different strains.

Myths About Measles Strains

Do the measles vaccines cover all of the measles strains that cause outbreaks around the world?

Yes they do, despite the myths you may hear about mutated measles strains.

This came up a lot during the Disneyland measles outbreak, when folks first tried to place blame on a vaccine strain and then on the fact that the outbreak strain didn’t match the vaccine strain.

“…California patients were genotyped; all were measles genotype B3, which has caused a large outbreak recently in the Philippines…”

CDC Measles Outbreak — California, Dec 2014–Feb 2015

And it is coming again in the latest measles outbreak in Minnesota. Could that outbreak be caused by a vaccine strain? Anything is possible, but it’s not. A communication’s director for the Minnesota Department of Health has confirmed that “that the virus strain making people sick in this outbreak is the B3 wild-type virus.”

Of course, none of these outbreaks are started by a vaccine strain of measles shed from someone who was recently vaccinated. It also had nothing to do with the fact that the strains didn’t match – after all we aren’t talking about the flu.

These outbreaks are imported from other countries by folks who typically aren’t vaccinated or are incompletely vaccinated and mostly spread among other people who are unvaccinated.

So what’s the most important thing to understand when considering all of these vaccine strains and wild strains of measles? It is that “there is only 1 serotype for measles, and serum samples from vaccinees neutralize viruses from a wide range of genotypes…”

In other words, the measles vaccine works against all strains of measles in all genotypes of measles. That makes sense too, because the measles virus, unlike influenza, is monotypic.

There is only one main type of measles virus, despite the many small changes in the virus that can help us identify different strains and genotypes. And these changes don’t affect how antibodies protect us against the measles virus.

What To Know About Measles Strains

The best way to get protected against all measles strains is to get vaccinated with two doses of the MMR vaccine.

More About Measles Strains

Updated May 23, 2017

Measles Deaths in the 21st Century

An infant hospitalized during a measles outbreak in the Philippines in which 110 people died.
An infant hospitalized during a measles outbreak in the Philippines in which 110 people died. Photo by Jim Goodson, M.P.H.

Measles is a big killer.

According to the WHO, “In 2015, there were 134,200 measles deaths globally – about 367 deaths every day or 15 deaths every hour.”

But it wasn’t that long ago, in 1980, that measles was causing at least 2.6 million deaths a year. And just 17 years ago, in 2000, measles caused about 777,000 deaths worldwide.

Measles Deaths in the 21st Century

While some experts doubt if we will ever truly eradicate measles, like we have done for smallpox, a lot of progress is being made on reducing measles outbreaks and deaths thanks to routine and supplemental immunizations.

Tragically, measles still kills.

“For every 1,000 children who get measles, one or two will die from it.”

CDC – Complications of Measles

And it is not just in developing countries that don’t have access to vaccines or adequate levels of vitamin A or modern healthcare.

During the 2010 and 2011 outbreaks in Europe, after all, with about 30,000 cases of measles each year, there were at least 28 deaths.

So far this year, there are reports of :

  • the death of a 10-month-old unvaccinated child in Bulgaria (among just 61 cases)
  • the death of a 17-year-old girl who was not vaccinated in Portugal (among just 23 cases)
  • 21 deaths in Romania, almost all unvaccinated children (among 4,793 cases since January 2016)
  • the death of a vaccinated man who was being treated for leukemia in Switzerland (among just 52 cases)
  • the death of a 37-year-old partially vaccinated women (the mother of 3 kids) in Essen, Germany (among about 504 cases)

Unfortunately, measles cases continue to rise in most of these countries and many others…

Are you planning a trip to Europe any time soon? How about Indonesia or Australia, for which the CDC has also issued travel health notices. Even if you aren’t, as these outbreaks rise, it increases the chances that another traveler will bring measles home and expose someone in your community, starting an outbreak.

And while we deal with folks who simply don’t want to vaccinate and protect their kids, no one should lose sight of the fact that “In 2015, there were 134,200 measles deaths globally – about 367 deaths every day or 15 deaths every hour.”

What To Know About Measles Deaths

Kids are still dying of measles and the big take away should be that it doesn’t take thousands of cases for there to be a death and it can happen to a healthy child in a developed country with modern healthcare.

Get Educated. Get Vaccinated. Stop the Outbreaks

More Information About Measles Deaths

Updated May 23, 2017

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About Those Measles Outbreaks in China

The MMR vaccine is one of the most effective vaccines ever made. Two doses are at least 99% effective at preventing measles infections. Even one dose is about 95% effective against measles.

We have measles outbreaks in the United States not because the MMR vaccine is not effective, but rather because there are still so many unvaccinated people around. Often, these unvaccinated people travel out of the country, get sick with measles, and start the outbreaks.

About Those Measles Outbreaks in China

A study in PLOS did not find massive outbreaks of measles in China despite high vaccination rates.
A study in PLOS did not find massive outbreaks of measles in China despite high vaccination rates.

But if the MMR vaccine is so effective, then why, as many anti-vaccine folks claim, is China having measles outbreaks when 99% are vaccinated?

The simple answer is that this claim is false – China is not having these big measles outbreaks among highly vaccinated people.

The source of the claim is from a real article in PLoS One, “Difficulties in Eliminating Measles and Controlling Rubella and Mumps: A Cross-Sectional Study of a First Measles and Rubella Vaccination and a Second Measles, Mumps, and Rubella Vaccination,” which found that in 2011, in Zhejiang province, there were:

  • 9 patients with measles, including 3 infants who were too young to be vaccinated and 6 young adults who were unsure if they had ever been vaccinated
  • 1122 patients with mumps
  • 186 patients with rubella

So no big measles outbreaks, but why the large number of cases of mumps and rubella?

History of Measles Vaccination in China

It becomes easy to understand when you look at their immunization schedule.

In the United States, the first live measles vaccine was introduced in 1963, the MMR was introduced in 1971, and a booster dose of MMR was added to the childhood immunization schedule in 1990. That helped to stop the endemic spread of measles in 2000 and rubella in 2004.

In contrast, the measles vaccine timeline has moved much slower in China:

  • a measles vaccine was introduced in 1966
  • continued use of a one-dose, single-antigen measles vaccine through the 1970s and mid-1980s
  • the addition of a single-antigen measles vaccine booster dose in 1985 to children who were 7-years-old
  • in 2007, the switch to a measles-rubella vaccine for 8 months old, with a MMR booster at 18-24 months
  • the addition of a measles-rubella vaccine booster for secondary school students in 2008
  • a campaign to get children between the ages of 8 months and 4 years vaccinated with a measles-mumps vaccine in 2010

So many of the children and young adults who had mumps and rubella would not have had a chance to get a mumps or rubella vaccine. They were too old when they started giving those vaccines and there was no catch-up for older children and adults.

The study authors conclude that a timely two-dose MMR vaccination schedule is recommended, with the first dose at 8 months and the second dose at 18–24 months. An MR vaccination speed-up campaign may be necessary for elder adolescents and young adults, particularly young females.

What To Know About Those Measles Outbreaks in China

Even considering the varied vaccine schedule, the study also clearly states that even for the measles vaccine, there is less than 95% coverage in almost all age groups and that measles cases are at an historic low.

It should be clear that anti-vaccine websites are putting out false information when they say that China is having measles outbreaks when 99% of the population is vaccinated.

More About Those Measles Outbreaks in China