The first time you can get the MMR vaccine is at 12-15 months old. Children under that age and people who are unable to get vaccines for medical reasons (eg they are allergic to the vaccine or have a weakened immune system) rely on herd immunity to not get sick. If enough people are vaccinated against a contagious disease (in the case of measles, 95 percent of the population) they create protection for the unvaccinated.
This 6-second gif gives a pretty good explanation of how herd immunity works.
Protection of the young and the vulnerable relies on others who can get vaccinated doing so. Unfortunately, as several mothers have found out over the last few months, the levels of vaccinations in the population may not be high enough to offer this layer of protection.
Sara Blum, from California, has shared her "terrifying" ordeal of her baby catching measles after discovering that her 5-month-old son Walter had a rash and a fever of 39°C (102.5°F). He was diagnosed with measles, and fortunately, after receiving medical care, he recovered well.
“This would have been 100% preventable if people would just trust doctors and science, and vaccinate their children rather than going off of their own opinions and doing their research through Facebook,” Blum wrote in a now-hidden Facebook post where she shared pictures of her son's full-body rash, MSN reports.
“Because of them, my little boy had to get measles and suffer. Luckily there were no major complications and he is doing okay, but it could have easily been a different turnout. He is only 5 months old and didn’t even have a chance to get vaccinated."
In an emotional part of the post, Blum said her son had been sick for one-fifth of his life and probably “thinks this is part of life.” Blum worked closely with her local public health department, reporting any potential exposure so that others didn't have to go through the same ordeal.
She is not the only person sharing a story like this recently. Earlier this month another mother, this time Jilly Moss in the UK, shared a similar story of her young daughter, who is less than a year old, catching measles and having "her eyes swollen shut for 4 days" and a high fever that lasted for over two weeks.
"The truth is this all could have been prevented if the protection layer of older kids above Alba had been vaccinated," she wrote in her own Facebook post.
In 2019 so far in the US there have been 704 confirmed cases of measles, nearly double the number of cases in the whole of 2018, according to the Center for Disease Control and Prevention (CDC). An outbreak of particular concern is taking place in New York, where there have been over 300 cases this year, mainly concentrated in the Orthodox Jewish communities in Brooklyn, which anti-vaxxers are reportedly targeting with misinformation.
"When measles is imported into a community with a highly vaccinated population, outbreaks either don’t happen or are usually small. However, once measles is in an under-vaccinated community, it becomes difficult to control the spread of the disease," the CDC said in a statement.
Measles was eliminated in the US in 2000, but "the longer these outbreaks continue, the greater the chance measles will again get a sustained foothold in the United States," the CDC warns.