Vaccine Reactions: Fact or Fiction?


While many children handle vaccines without any noticeable difficultly, some have reactions which cause understandable concern among parents – concern which can affect how and if they continue vaccinating their children. Adults suffer side effects too. Just how real are these reactions? The Centers for Disease Control and Prevention has created a Vaccine Information Statement (VIS) for every vaccine so that consumers can understand the small risk of moderate to severe side effects which may occur. Vaccine Product Inserts, written and distributed by the vaccine manufacturers, provide even more detailed information.

DTaP vaccine (Diphtheria, Tetanus, Pertussis):

The CDC tells parents that about 1 in 1000 babies will react with non-stop crying for 3 or more hours. What the CDC fails to disclose, however, is this type of crying after receiving vaccines refers to what is known as encephalitis, which is much more harmful than the “standard fussiness” common after most vaccines. Encephalitis is actual swelling and inflammation of the brain, and it can cause permanent harm. A risk of 1 in 1000 may sound small, but realize that infants take a risk with each dose – 3 doses in the first six months of life, and 6 total doses throughout childhood. The CDC also warns that DTaP can cause long-term seizures, coma, or permanent brain damage in rare instances. Vaccine product inserts for DTaP also discuss side effects including brachial neuritis (nerve dysfunction in the injected arm) and Guillain-Barré syndrome (temporary, or sometimes permanent, paralysis or muscle weakness).

Hepatitis B vaccine:

The product insert warns the vaccine can also cause fever, poor feeding, lethargy, and irritability in newborns. These are potentially-serious symptoms that could impact a newborn’s ability to thrive and develop in the early weeks and may require invasive medical testing and treatment. Hepatitis B is a sexually-transmitted blood-born disease, so newborns are not at risk (unless the mother is already infected). Adult side effects are also possible, including autoimmune and neurological reactions.

Pneumococcal vaccine:

The vaccine product insert warns that during the initial safety testing, severe reactions occurred in 8% of test subjects, most commonly pneumonia, severe wheezing, and intestinal infection. The CDC states that when given at the same time as a flu vaccine, common at 6 month or 12 month appointments, an infant has about a 1 in 1600 chance of having a febrile seizure reaction. While some believe febrile seizures to be harmless, research does show possible connections to ongoing epilepsy. The CDC also reveals that nearly all infants become fussy or irritable (8 out of 10) with each dose, and about half suffer drowsiness and poor feeding. This vaccine is given to infants in 4 doses at the same time as DTaP and Hepatitis B, which may compound the likelihood and harm of these common reactions for young infants.

Rotavirus vaccine:

The CDC cautions that the Rotavirus vaccine can cause intussusception in up to 1 in 20,000 infants. This serious intestinal blockage can be fatal and can require emergency surgery to correct. It is also important to note that a version of Rotavirus vaccine was taken off the vaccine schedule in 1999 because of safety risks and a higher frequency of intussusception. Two other serious reactions disclosed in the product insert are seizures in 1 in 1000 infants and Kawasaki disease (a severe autoimmune reaction that can trigger a heart attack) in 1 in 10,000.

MMR vaccine (Measles, Mumps, Rubella):

The CDC warns that this vaccine can cause a febrile seizure reaction in about 1 out of every 2500 doses; when given combined with the Chicken pox vaccine (standard practice for most pediatricians at the 12 month appointment), seizure is twice as likely- 1 in 1250 doses. Two doses are recommended for infants and children. The CDC also reports that this vaccine can very rarely cause long-term seizures, coma, or permanent brain damage. There is also a warning for women: the vaccine causes moderate to severe arthritis in 1 in 4 teen or adult women; and a small percentage of these women go on to suffer permanent autoimmune arthritis. The product insert adds side effects including deafness, encephalitis, multiple nerve dysfunction, vision loss, testicular swelling, and bleeding problems.

Flu vaccine:

A serious adverse reaction to the flu vaccine, according to the CDC, is a neurological condition called Guillian-Barre syndrome – a temporary paralysis which can be fatal. In some cases, the paralysis is permanent. The vaccine is now recommended for all children beginning at six months of age (two doses, one month apart). The flu vaccine is also known to cause rare but fatal allergic reactions, particularly in those who are allergic to eggs. Most infants don’t eat eggs until after their first year, leaving allergy status unknown for those first two doses. This makes early administration of the flu vaccine even more risky. Other side effects noted in the product inserts include seizures, inflammation of the brain and spinal cord, and multiple nerve dysfunctions (one brand of the flu vaccine lost its pediatric approval when it was found to cause a febrile seizure in 1 in 200 infants). Many brands of the flu vaccine still contain mercury/thimerosal, and although some states have outlawed mercury, like CA, it has still been given 6 out of the last 10 years because of perceived shortages of mercury-free alternatives.

All vaccines carry about a 1 in a million risk of causing life-threatening anaphylactic shock, a statistic often misquoted as the risk of all serious events. Vaccine product inserts warn about other rare, but potentially fatal, side effects. The CDC receives about 30,000 reports of vaccine reactions every year: about 2000 of these are serious and result in prolonged hospitalization, permanent disability, or death.

While severe side effects remain rare, moderate reactions that may cause permanent harm are not. Ask your health care provider to review the possible risks of your child’s vaccinations at your next health check-up. Asking questions does not make you anti-vaccination . . . it makes you pro-immunity education.

To review the CDC Vaccine Information Statements for yourself, click here 

To view Vaccine Produce Inserts, click here.