Officials in New South Wales, Australia, had to issue their 15th measles warning of 2019 this week, following two separate incidents involving babies too young to be vaccinated, The Guardian reports. Both infants reportedly contracted the virus in Sydney last month.

Sadly, this is not an anomaly. Forty-six cases of measles were reported in New South Wales between January 2017 and November 2018. This number has jumped in recent months, with 28 recorded in the last four months alone.

But it's not just Australia. Measles is making its comeback global – according to the World Health Organization, the number of cases reported worldwide has increased by some 30 percent since 2016.

In the US, outbreaks have popped up in counties across the States, including in Portland, Washington, and New York. Three months into 2019 and the number of measles cases topped those for the entirety of 2018.

Across the Atlantic, in Europe, the number of measles cases in 2018 were triple what they were in 2017 – and 15 times higher than in 2016. Large outbreaks are cropping up in Ukraine, Madagascar, and elsewhere.

Measles is a preventable disease, which means its comeback really comes down to just one thing – vaccination, or rather, a lack of. Sometimes, this may be unavoidable due to restricted access to medical resources, but often it is a voluntary decision.

More and more people appear to be choosing not to vaccinate their children. Indeed, the number of unvaccinated under-twos has quadrupled in the last 20 years.

This choice seems to be due to the spread of misinformation regarding the safety of vaccines. According to a recent study, the French are the most suspicious with 41 percent of respondents disagreeing with the statement "I think vaccines are safe".

While all medicines (including vaccines) have side effects, the vast majority, in this case, are extremely minor. Indeed, according to the National Health Service in England, vaccines are among the safest medicines you can take, with the most serious reactions affecting less than 1 in a million.

And yet, they are one of the best ways to deal with multitudes of viruses that have the potential to kill and disable hundreds of thousands if not properly controlled.

In these two incidences, both babies were too young to have been vaccinated but the illnesses may well have been prevented had other parents made sure to vaccinate their children. This is because of a concept called herd immunity.

The basic premise is that a whole community (or "herd") can be protected from a disease so long as a high enough proportion of the population is vaccinated. For measles, experts recommended that proportion is 90 to 95 percent of the population. This prevents the bacteria or virus causing the illness from being able to get a hold and spread. 

If that number is reached, it not only protects the vaccinated but those who can't be for health reasons. This could be because they are too young or because their immune system is weakened, either from treatment (for example, chemo) or an immuno-compromising condition like HIV. 

Countries are dealing with the crisis in their own ways. Australia introduced a controversial but effective policy called “No Jab, No Pay”, cutting child benefits to parents who don't vaccinate their children. Italy has prohibited unvaccinated children from attending school and Uganda has threatened to jail parents who do not vaccinate their kids.

While the latter is certainly quite an extreme measure to take, there is only one way to deal with the problem and that is (say it with me, people) vaccination.