The American Medical Association (AMA) is worried that anti-vaxxers are weaponizing the world's biggest social media platforms, including Facebook, Google, and Twitter.

Parents often use these platforms to spread misinformation about vaccine dangers that aren't real.

Doctors say the content is having a dangerous impact on the number of vaccinated people in America, and that could have deadly consequences.

"I t is important that people be aware not just that these diseases still exist and can still debilitate and kill, but that vaccines are a safe, proven way to protect against them," the AMA letter states.

Doctors think too many American kids are missing vaccinations, and that fake news spreading like wildfire on social media platforms like Twitter, Facebook, and YouTube may be largely to blame.

On Wednesday, the American Medical Association (AMA), the largest professional group of doctors in the US, sent an open letter to the CEOs of Amazon, Facebook, Google, Pinterest, Twitter and YouTube, voicing concern that parents are taking in all kinds of fake information about childhood vaccines from inaccurate videos, posts, and links on their platforms.

"Physicians across the country are troubled by reports of anti-vaccine related messages and advertisements targeting parents searching for vaccine information on your platforms," AMA CEO James Madara wrote. "We urge you to do your part to ensure that users have access to scientifically valid information on vaccinations, so they can make informed decisions about their families’ health."

The anti-vaxx content that's been cropping up on social media for years appears to be having a harmful effect: a recent UK study suggested that two in every five parents have been exposed to anti-vaccine content on social media, and more than one in four believe, wrongly, that a person can have "too many" vaccines.

In the US, researchers are worried about several potential "hotspots" that are ripe for a disease outbreak, including Portland, Oregon; Seattle, Washington; Phoenix, Arizona; Salt Lake City, Utah; Houston, Texas; and Detroit, Michigan.

Measles, a vaccine-preventable disease that was nearly unheard of in the US as recently as the early 2000s, is cropping up in more and more rich countries where people are neglecting their shots. In 2018, measles killed 72 people in Europe, and over 225 people in the US have contracted measles so far this year.

Some big tech companies are starting to take note.

Last Thursday, Facebook promised to de-rank anti-vaxx pages on its site. Ethan Lindenberger, an 18-year-old who has recently taken it upon himself to start catching up on his own childhood vaccines, said his mother often used Facebook to spread false information about vaccines to her friends, and inform her beliefs that vaccines were dangerous for him.

"Her love, affection, and care as a parent was used," Lindenberger told the Senate Committee on Health, Education, Labor, and Pensions last week.

Pinterest is taking a more conservative approach by completely blocking vaccine searches. Amazon is also taking steps to remove anti-vaxx videos and stop selling books with quack medical "cures," as NBC reported Tuesday.

Rhett Krawitt (pictured here with mom Jodi) can't get shots because his immune system is too vulnerable. Krawitt relies on the power of a large, vaccinated population to shield him from diseases. Reuters/Elijah Nouvelage

Doctors could also be doing more to combat the problem, as studies suggest they are some of the most trusted sources that vaccine-hesitant parents may consult to change their minds. Here's the AMA's letter in full:

Dear CEOs of Leading Technology Companies,

At a time when vaccine-preventable diseases, particularly measles, are reemerging in the United States and threatening communities and public health, physicians across the country are troubled by reports of anti-vaccine related messages and advertisements targeting parents searching for vaccine information on your platforms. As physicians, we are concerned that the proliferation of this type of health-related misinformation will undermine sound science, further decrease vaccinations, and persuade people to make medical decisions that could spark the spread of easily preventable diseases.

With public health on the line and with social media serving as a leading source of information for the American people, we urge you to do your part to ensure that users have access to scientifically valid information on vaccinations, so they can make informed decisions about their families’ health. We also urge you to make public your plans to ensure that users have access to accurate, timely, scientifically sound information on vaccines.

We applaud companies that have already taken action but encourage you to continue evaluating the impact of these policies and take further steps to address the issue as needed.

The overwhelming scientific evidence shows that vaccines are among the most effective and safest interventions to both prevent individual illness and protect public health. When immunization rates are high, people who cannot be protected directly by the vaccines are protected because they are not exposed to the disease. This includes children too young to receive vaccinations and people with medical contraindications.

The reductions we have seen in vaccination coverage threaten to erase many years of progress as nearly eliminated and preventable diseases return, resulting in illness, disability and death. In order to protect our communities’ health, it is important that people be aware not just that these diseases still exist and can still debilitate and kill, but that vaccines are a safe, proven way to protect against them.

As evident from the measles outbreaks currently impacting communities in several states, when people decide not to be immunized as a matter of personal preference or misinformation, they put themselves and others at risk of disease. That is why it is extremely important that people who are searching for information about vaccination have access to accurate, evidence-based information grounded in science.

Thank you for your attention to this critical, public health matter. We look forward to hearing from you.

Sincerely,

James L. Madara, M.D.

CEO, Executive Vice President, Americal Medical Association