False claims and conspiracies spread amid rise in US measles cases

Measles cases in Florida and 14 other states prompted a spike in conversation across platforms about the disease and the measles vaccine. These conversations include a range of narratives, including accurate information, discussion about public health guidelines during a measles outbreak, and false claims. Much of the discourse about the outbreak is related to the Florida surgeon general’s letter to parents, which does not encourage vaccination and allows unvaccinated children to continue attending school. Some posts online falsely claim that COVID-19 or measles vaccines caused the outbreak, while others argue that measles isn’t serious and that vaccines are unnecessary. Viral videos trending on multiple platforms are also discussing immune amnesia, stating that measles “completely wipes out” existing immunity against other diseases.

Risk level: High

Recommendation: False claims about measles and the measles-mumps-rubella (MMR) vaccine can contribute to declining pediatric vaccination rates. They may also discourage patients from isolating after a potential measles exposure, which could lead to further cases of the disease. In Florida, guidance from the surgeon general conflicts with CDC guidelines, which elevates the risk.

Talking points may emphasize that measles is a serious and extremely contagious disease, and children without immunity are at high risk of contracting measles if exposed. Measles can cause serious long-term damage to the immune system, and measles immune amnesia is a real phenomenon, although it does not completely erase existing immunity, as some have suggested. The MMR vaccine does not cause measles; the vaccine is the best protection against the disease. Two doses of the MMR vaccine are 97 percent effective against measles and provide lifetime immunity. The CDC recommends that children receive their first dose of the MMR vaccine at 12 to 15 months old and their second dose at four to six years old, but any unvaccinated person can receive the vaccine within 72 hours of exposure.

The CDC also recommends that unvaccinated people isolate for the 21-day measles virus incubation period after exposure.