Scientists find even a small dip in measles vaccination numbers could spark a major outbreak

A new study sheds light on the potentially disastrous consequences of not vaccinating. Photo / Getty

A reduction as small as five percent in the number of people getting vaccinated for measles could lead to three times the number of annual cases of the disease, a new study shows.

Researchers from the Standford University School of Medicine and Baylor College of Medicine have found that it doesn't take a big dip in the number of people getting vaccinated for an outbreak to happen.

In fact, a five percent reduction in the number of children ages two to 11 getting the measles vacinne could see the number of cases of the disease as much as triple for that age group.

The numbers would be substantially higher if unvaccinated infants, adolescents, and adult populations were also considered, the study also warned.

The researchers also calculated that the public health costs of such a scenario could be as high as US $3 million.

"We focused on measles as a case example of the effects of declining vaccine coverage because it is highly infectious," Nathan Lo, the study's lead author, said in a statement.

"It's likely to be the first infectious disease causing outbreaks if vaccination declines."

The researchers say even minor reductions in childhood vacinnation, drive by vaccine hesitancy (nonmedical and personal belief exemptions), can have great public health as well as economic consequences.

The experts are calling for a public discussion on the issue of vaccine hesitancy, saying a lot of parents base their decision to not vaccinate on misinformation, such as a low perceived risk of measles, as well as misinformation on the side-effects of vaccines.

"Our study conclusions find that measles still poses a substantial threat for large outbreaks in children, despite public perception that measles is no longer a risk to children in the United States, especially under scenarios with further decline in vaccine coverage. Furthermore, the safety of MMR and other vaccines is well established in the scientific literature, including the finding that MMR vaccination has no association with the development of autism."

They point out that measles is a highly contagious disease, which spreads through the air. The viral disease requires a high vaccine coverage (>90%-95%) to achieve herd immunity and stop large outbreaks (Based on an estimated 95% vaccine efficiency).

What this means is that vaccines are much more than a personal issue as herd immunity is vital to protect other members of the community.

Reddit user "theotheredmund" recently created an animated gif that attempts to use visualisation to explain how herd immunity works. The gif was created using data from Epidemiologic reviews and attempts to show how vaccinating not only protects the one receiving the vaccine but also those around them.

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According to Statistics New Zealand, the government and Ministry of Health have set goals to increase immunisation rates to 95% for eight-month-olds and two-year-olds.

The study was published this week in JAMA Pediatrics.