Claims about thimerosal, including its mythological connection to autism, are gaining new life because of an announced vote regarding thimerosal in influenza vaccines during the ACIP meeting.

We know a lot now about thimerosal. Thimerosal, a mercury compound used today in some flu vaccines, has caused concern due to its name being confused with a harmful type of mercury. Thimerosal contains ethylmercury, which is safe and quickly leaves the body. It’s different from harmful methylmercury found in some fish. Thimerosal has been used safely in vaccines, drugs, and contact solutions since the 1930s. Nowadays, most vaccines use single-use vials, and thimerosal-free vaccines are available for those still concerned.

To drum up concerns, vaccine opponents have to travel back in time and make dull government meetings look nefarious. Such is the case with Simpsonwood.

The 2000 Simpsonwood CDC conference was a two-day meeting organized by the CDC to discuss data from the Vaccine Safety Datalink regarding the possible link between the mercury compound thimerosal in vaccines and neurological issues in vaccinated children. Attendees included experts in various fields, public health organizations, and pharmaceutical companies.

The conference gained notoriety in the anti-vaccination movement when RFK Jr. wrote an article in 2005 alleging a conspiracy to withhold vaccine safety information. However, the article contained numerous factual errors, leading to its retraction.

In 2007, the Senate HELP Committee reviewed the allegations against the CDC and found them to have little merit. The committee found that the CDC did not interfere with vaccine safety studies, and the review groups did not rely on manipulated studies.

Studies show that thimerosal does not increase the risk of autism. In addition, thimerosal has not even been used in childhood vaccines since 2001.

Finally, autism diagnoses continued to rise following the 2001 removal of thimerosal from all childhood vaccines. The continued rise of autism diagnoses is, in fact, mostly due to growing awareness and changing diagnostic criteria.

Autism is linked to genetics and prenatal development, not vaccines. Studies show that if one identical twin has autism, there is a high chance the other twin will, too, even if they were never vaccinated. Research also shows that brain differences in autistic children start developing before birth, long before any vaccines are given. Scientists have studied many possible causes, and vaccines are not a possible cause.

RSV concerns continue to circulate, also due to the vaccine’s inclusion in the ACIP agenda.

It is advised to limit tuna consumption during pregnancy due to methylmercury exposure. Conversely, the RSV vaccine is recommended in pregnancy to protect that same baby through passive immunity after they are born. RSV is a respiratory disease that can be very dangerous in infants and young babies. Vaccinating the mother in pregnancy between 32-36 weeks allows her to create antibodies which will then pass through the placenta to the fetus, protecting them from RSV for several months after birth.

Some claim that RSV vaccines could cause pre-term birth, and that pharmaceutical companies knew this, but pushed the FDA to approve them nonetheless.

As a member of the FDA advisory committee, Dr. Paul Offit was directly involved in these discussions. During a publicly available webinar, Dr. Offit observed that an initial safety signal concerning pre-term birth appeared only in lower- and middle-income countries. But in those places, the presence of an additional vaccine is not linked to an increase in prematurity rates in the vaccine group.

Instead, there is a clear decrease in prematurity rates in the placebo group. Individuals in the placebo group were more likely to have received a COVID-19 or flu vaccine, reducing the risk of prematurity from those diseases.

In a video posted on Twitter, ACIP committee member Robert Malone claims that vaccines aren’t very effective and that warnings about unvaccinated kids endangering others are just scare tactics.

Vaccines work. They are not 100% effective, but for many, vaccines protect against disease, hospitalization, and death. Because vaccines don’t work 100% of the time, some people will be vulnerable to a disease even though they have been vaccinated. Also, some people cannot be vaccinated because they are too young or immunocompromised, so they are vulnerable, too. Those people are at risk of get sick or worse from a disease, so if others in their community are unvaccinated and therefore susceptible to contracting and passing along a disease, those people pose a risk to those who aren’t protected by their own vaccines.

Herd immunity, or community immunity, happens when enough people in a community are immune to a disease that they “shield” those who don’t have immunity from getting the disease. What constitutes “enough” is dependent on how contagious a specific disease is. If not enough people in a community are vaccinated and the threshold to reach herd immunity is not met, then anyone who is susceptible to the disease, whether unvaccinated for personal or medical reasons, or for those for whom the vaccine didn’t work, is at risk from the disease.

Studies show that when vaccination rates drop, diseases return. For example, measles outbreaks tend to happen in areas with low vaccination rates. Then even the vaccinated are at increased risk of getting sick or worse.