Vaccine Side Effects

It has been said that pro-vaxers (i.e. docs, especially pediatricians), always talk about vaccine benefits and rarely about side effects. I agree! So today I want to talk about some of the side effects most commonly encountered with the routine vaccines we give to children.

Overall I think the reason that we accentuate the positive with vaccines is for 2 reasons: time and odds. Time is the biggest reason, at least for me. In my usual 15 minutes for a well visit, I need to take a history, discuss concerns, examine my patient, show parents growth charts, discuss any abnormal findings, AND then talk about labs and vaccines that are due. As we already give out a Vaccine Information Statement (aka VIS) that lists individual vaccine side effects with each vaccine, most docs, me included, are a little fast and loose with discussing vaccine side effects in detail unless a parent has specific questions.

Odds are a different story. Doctors are trained in thinking about risk:benefit ratios, making choices that serve the greatest good, and taking a global perspective of a patient’s health. This means (I hope) that we presume that a parent will share our perspective of, say, the value of receiving a measles, mumps and rubella vaccine despite the pain of vaccination, the chance of rash and fever, and the small possibility of more severe side effects such as a febrile seizure.

Some side effects of vaccination are common to almost all vaccines given, while some are particular to a certain vaccine or when certain vaccines are given together. Also, due to how side effects are monitored, almost any symptom might occur after a vaccine, whether it was an actual side effect or just a coincidence. Some definite side effects are very serious but also very rare, which makes the vaccine “worth” giving to people in general although horrible for those who experience the severe side effect (see “odds” above).

So in no particular order, here is my take on some vaccine side effects.

Side effects of most or all vaccines:

Pain: ok, I know this is obvious, but it’s also by far the biggest factor for all young children and lots of older ones as well. Any injection is likely to cause pain although some kids seem not to care very much, even after the shot has been given. Pain is most commonly present for up to a day or two after vaccination, at the site of the injection. Pain meds like acetaminophen and/or ibuprofen work well. If one is averse to medication, an ice pack can help.

Fever: also a biggie; timing varies by vaccine but commonly one should expect a fever in the 1-3 days following most vaccines. The big exception is the measles vaccine (either MMR or MMRV), which can cause fever starting anywhere from 5-12 days after vaccination and can last several days from then. Just like with pain, normally the best treatment for this is acetaminophen and/or ibuprofen. Also you can consider cool cloths draped onto your child. Do not try to put a child with a fever into a cold bath, because if he/she does have a febrile seizure (see below) that is the last place you want him or her to be, at risk for hitting the head or inhaling bath water or both.

Fussiness: many children are more fussy in the day or two after a vaccine; often it is hard to tell if this is due to fever or pain or the vaccine itself

Rash: common after MMR and varicella (aka chickenpox) vaccines or the two combined as MMRV, rash usually happens in a similar time period as fever. There’s not much to do about it unless it itches, in which case a topical anti-itch medicine or moisturizing lotion may help.

More uncommon side effects:

Febrile seizure: this is an uncommon side effect but one that can occur after vaccination. Febrile seizures usually occur as a child’s temperature is rising, and the is usually not any warning beforehand. They are most common in children from 6 months to 5 or 6 years old, which is also an age range when lots of vaccines are given. Thankfully, febrile seizures are usually very brief (under a minute) and almost always stop on their own. If this occurs, after making sure the child is in a safe place (safe from falls, sharp objects and other dangers) you should call you child’s doctor but there is usually not much to do as the seizure is usually over before you reach anyone. Of course, a prolonged seizure should prompt a call for an ambulance. See below for a reference about this. *It has been found that in 12-15 month olds, febrile seizures are more common when the MMR and varicella vaccines are given at the same time, so many doctors give them at different visits, say one at 12 months and the other at 15 months old.

Fainting: fainting, if it occurs, is most common in the 10-30 minutes right after a vaccination. It seems to happen much more commonly with teens than with younger children. The biggest worries are getting injured during a fall, especially head injuries. Some people are prone to faint after vaccines, so with them a period of waiting while sitting down for 15 or 20 minutes after being vaccinated is advised.

A rare one but a big deal:

Guilian-Barre Syndrome: this is a rare but serious condition that usually occurs after infections but can also rarely occur after influenza vaccination. It is a rapidly worsening tingling of nerves and weakness of muscles and can be life-threatening for some. Again, rare but very serious. People with a history of GBS are not given flu vaccine.

Whew! That is a quick summary of some more common vaccine side effects. There are many more as well, feel free to comment if you like.

This reference on measles-contains vaccines is from the CDC; it’s long but pretty comprehensive; with an excerpt below:
https://www.cdc.gov/mmwr/preview/mmwrhtml/00046738.htm

The following recommendations concerning adverse events associated with measles vaccination update those applicable sections in “Measles Prevention: Recommendations of the Immunization Practices Advisory Committee” (MMWR 1989; 38{No. S-9}), and they apply regardless of whether the vaccine is administered as a single antigen or as a component of measles-rubella (MR) or measles-mumps-rubella (MMR) vaccine. Information concerning adverse events associated with the mumps component of MMR vaccine is reviewed later in this document (see Mumps Prevention), and information concerning the rubella component is located in the previously published ACIP statement for rubella (18).

Side Effects and Adverse Reactions

More than 240 million doses of measles vaccine were distributed in the United States from 1963 through 1993. The vaccine has an excellent record of safety. From 5% to 15% of vaccinees may develop a temperature of greater than or equal to 103 F ( greater than or equal to 39.4 C) beginning 5-12 days after vaccination and usually lasting several days (19). Most persons with fever are otherwise asymptomatic. Transient rashes have been reported for approximately 5% of vaccinees. Central nervous system (CNS) conditions, including encephalitis and encephalopathy, have been reported with a frequency of less than one per million doses administered. The incidence of encephalitis or encephalopathy after measles vaccination of healthy children is lower than the observed incidence of encephalitis of unknown etiology. This finding suggests that the reported severe neurologic disorders temporally associated with measles vaccination were not caused by the vaccine. These adverse events should be anticipated only in susceptible vaccinees and do not appear to be age-related. After revaccination, most reactions should be expected to occur only among the small proportion of persons who failed to respond to the first dose. Personal and Family History of Convulsions

As with the administration of any agent that can produce fever, some children may have a febrile seizure. Although children with a personal or family history of seizures are at increased risk for developing idiopathic epilepsy, febrile seizures following vaccinations do not in themselves increase the probability of subsequent epilepsy or other neurologic disorders. Most convulsions following measles vaccination are simple febrile seizures, and they affect children without known risk factors.

An increased risk of these convulsions may occur among children with a prior history of convulsions or those with a history of convulsions in first-degree family members (i.e., siblings or parents) (20). Although the precise risk cannot be determined, it appears to be low.