Clinton is the prohibitive favorite for the Democratic presidential nomination in 2016 and the tweet was seemingly aimed Republican presidential hopefuls
who have questioned whether vaccinations should be required and whether they are tied to mental disorders.
Clinton ends the tweet with a nod to her granddaughter, Charlotte, who was born late last year. Clinton regularly used her grandmother status as a rhetorical tool while campaigning for Democrats in 2014.
Federal health officials have expressed concern over a recent measles outbreak that has been fueled by skepticism among some parents of infant vaccination schedules. Measles is a disease that children a regularly vaccinated against.
The issue has become political, despite the fact that claims like vaccines leading to childhood autism have been debunked by scientific research.
Sen. Rand Paul of Kentucky questioned
the safety of vaccines when he said he had "heard of many tragic cases of walking, talking, normal children who wound up with profound mental disorders after vaccines."
"I'm not arguing vaccines are a bad idea. I think they're a good thing. But I think the parents should have some input," he said during an interview on CNBC.
New Jersey Gov. Chris Christie, when asked about the issue, said that he choose to vaccinate
his children, but added, "Parents need to have some measure of choice in things as well, so that's the balance that the government has to decide."
Former Hewlett-Packard CEO Carly Fiorina, who is also exploring a 2016 run, told Buzzfeed
that while she thinks vaccinating for the measles makes sense, the decisions should be up to the parents.
But renowned neurosurgeon Ben Carson, also a potential Republican presidential candidate, broke from the pack and defended mandatory vaccinations.
"Certain communicable diseases have been largely eradicated by immunization policies in this country and we should not allow those diseases to return by foregoing safe immunization programs, for philosophical, religious or other reasons when we have the means to eradicate them," he told Buzzfeed.
But Carson aside, these comments from Paul, Christie and Fiorina contradict with what Clinton tweeted and President Barack Obama said in an interview on Sunday.
"I understand that there are families that, in some cases, are concerned about the effect of vaccinations," Obama told NBC News before the Super Bowl. "The science is, you know, pretty indisputable."
Both Obama and Clinton have altered their opinions on this issue, though, because during the 2008 presidential nomination fight, the two left the door open to vaccines causing autism and other issues.
the science was "inconclusive," while Clinton wrote in an anti-vaccine questionnaire
that she was "committed to make investments to find the causes of autism, including possible environmental causes like vaccine."
The Republican National Committee noted that Clinton altered her position in a statement to CNN on Tuesday.
"Since Hillary Clinton is running for President Obama's third term, it's no surprise she abruptly changed her position just 24 hours after he restated his," said spokesman Michael Short.