There's nothing like parenting to bring out the "experts" and the naysayers.

With the rise of the #WalgreensFluFighter hashtag on Instagram, this week's topic of choice is whether or not to vaccinate our children—and the anti-vaxxers are taking it personally.

As a part of this year's promotional materials and their mission to improve everyone's health nationwide, Walgreens has launched the hashtag #WalgreensFluFighter in partnership with leading social media influencers.

Those with more than twenty-thousand followers on Instagram, as well as social leaders in the health and parenting niches, received an email from Walgreens' marketing department. For this season, influencers have the opportunity to receive $200 after receiving their annual flu shot at their local Walgreens pharmacy and sharing their flu shot story on Instagram, with the hashtags "WalgreensFluFighter" and "ad."

Unfortunately, what should have been a simple visit to the pharmacy and a quick Instagram post has come at quite a cost to some influencers—though the cost is nothing medical.

Rather, anti-vaxxers have swiftly moved in on the movement.

They've been using the movement's hashtag as a way to draw attention to their own agenda. They've also been actively posting on vaccination positive posts in condescending and even threatening ways.

One family, Bryce and Jeffrey of @thisiswherewestarted, a same-sex couple with two children, are used to negative comments. But nothing compared to what they received after participating in Walgreen's sponcon.

Bryce and Jeffrey said:

"There were comments talking about how we don't deserve children or that we might as well just kill our children. Being a same-sex couple, we are used to people leaving mean comments while hiding behind their keyboard. We were shocked at the level of comments we received."

And the couple is not alone. Other Instagram influencers have received similar treatment from anti-vaxxers.

Mom Shannon of @boys_plus_triplets, experienced the irony that is often brought on by anti-vaxxers after they threatened her life for trying to take care of her children.

Shannon said:

"I was personally attacked by many of them and received some very threatening messages, which was very ironic [because] they wanted to hurt me for choosing to keep my children healthy."

Laura of @frugalforluxury experienced similar responses, some so severe that she considered keeping her children home from a family trip, fearing some of her more extreme attackers would track her down.

Laura said:

"The most vicious were saying that I'm poisoning my family… that it is child neglect."

On the flip-side, many on Twitter argued refusing to receive vaccinations is a form of child abuse.

They also pointed out how it endangers the surrounding community.

Whether or not a family decides to vaccinate, however, should not be cause for threatening remarks.