It's "flu-shot season" again, and the U.S. Centers for Disease Control and Prevention (CDC) continues to push vaccines on the population (pregnant women and infants included), in a futile effort to prevent cases of influenza. Towards the end of every season, we hear from the CDC that the efficacy of the vaccine was 62% or 58% or lower. But it is even worse. The percentages reported by the CDC are based on the ability to match the most prevalent strains of flu infections each year with the flu "antigens" used in the yearly shot. This does NOT take into account whether the flu shot actually confers any type of immunity to the patient. In fact, the prestigious Cochrane Review in 2014 stated that the flu vaccination "shows no appreciable effect on working days lost or hospitalization." Moreover, out of an average of 71 individuals receiving the flu shot, only one case of the flu was prevented.
A big issue to consider, besides the lack of effectiveness of the flu shot, is the risk associated with receiving the vaccine, especially for pregnant women. In early this year, Zerbo et al. (2017 JAMA Pediatrics) published a paper showing that pregnant women receiving the seasonal flu shot in the first trimester of pregnancy had 25% greater odds of having a child with Autism Spectrum Disorder (ASD).
Although the authors of the paper tried to dismiss the finding, given their deep institutional conflicts of interest as employees of the insurance giant Kaiser Permanente, later rebuttals to the paper by me (Hooker et al. 2017 JAMA Pediatrics) and a medical research group in Italy (Donzelli et al. 2017 JAMA Pediatrics) demonstrated that the finding was indeed statistically significant.
Even more alarming, the CDC just published a paper (Donahue et al. 2017 Vaccine) showing an increased risk of spontaneous abortion (miscarriage) in women receiving the seasonal flu shot during the 2010 through 2012 seasons. Although these vaccines carried the H1N1 antigen (for protection from Swine Flu) which is not used currently, the CDC could not rule out the fact that this association might exist in the type of seasonal flu vaccine distributed currently.

Over this next "flu-shot season", over 20 million of the influenza vaccines distributed will contain thimerosal, the mercury-laden preservative used in multidose vaccine formulations. This means that every adult, child, and infant receiving one of these flu shots will be exposed to 25 micrograms of mercury. Mercury in thimerosal has been linked to tics, speech delay, and language delay in children (Thompson et al. 2007 NEJM, Barile et al. 2013 J Pediatr Psychol, Verstraeten et al. 2003 Pediatrics, Andrews et al. 2004 Pediatrics) and many published studies also show a relationship with autism and ASD (Geier et al. 2013 Translational Neurodegeneration 2:25, among others). It's odd and unsettling that we warn pregnant women against tuna consumption because of mercury, but in contrast, allow them to get mercury containing flu shots. It has been well established that mercury from thimerosal selectively accumulates in the placenta and travels through cord blood to the developing fetus, who does not have any mechanism to detoxify heavy metals (Ablesohn et al. 2011 Canadian Family Physician 57:26).

Flu shots have been encouraged and marketed specifically to seniors as well. Yet the effect of thimerosal on older adults has not yet been studied. Information I have received from the CDC shows that their own epidemiologists proposed a study to CDC officials regarding mercury in the seasonal flu shot and the incidence of Alzheimer's disease. However, CDC leadership would not allow them to conduct such a study. To this end, only one study on PubMed by Spaeth et al. 2012 (J Neurosci Res) even mentions such a connection, suggesting that the pro-oxidative behavior of thimerosal could cause a type of cellular defect seen in Alzheimer's disease. However, mercury exposure is another story.

The presence of mercury amalgam fillings has been shown to correlate with the incidence of Alzheimer's disease (Sun et al. 2015 Alzheimer's Res Ther) and further, mercury exposure has been linked to the presence of Alzheimer's amyloid plaques in the brain (Kim et al. 2014 J Toxicol Sci.). However, even today, the CDC's website on thimerosal calls it the "safe mercury" which is quickly excreted from the body, which is not consistent with science. Instead, ethylmercury (the degradation product of thimerosal which circulates in the blood stream after exposure) is transported to the brain where it is converted to elemental mercury (the kind of mercury found in dental amalgams) which is essentially locked in the brain forever (Burbacher et al. 2005 Environ Health Perspectives). Given this fact, at a minimum, we need to study this effect further, specifically in senior populations who are highly vulnerable to neurodegenerative disorders.

Ultimately the decision to receive a flu shot is yours alone. I am a scientist, not a medical practitioner, and do not give medical advice, only present the scientific facts. That being said, I will not be receiving the influenza vaccine