On the other hand, truly significant vaccine adverse events are exceedingly rare.
Vaccine Side Effects vs.
Adverse Events
People often talk about vaccine side effects and adverse events interchangeably.
Common side effects occur in more than 1 in 100 people.
True adverse events, in contrast, are much more unexpected and idiosyncratic.
But some vaccine side effects may actually indicate that the vaccination process is working.
Different vaccines do this in different ways.
Live vaccines use live organisms that have been specifically altered to trigger an immune response.
Other types of vaccines use killed pathogens, or part of those pathogens, to trigger an immune response.
They prime the immune system by showing it something to rev it up.
In response, the immune cells go into action.
These cells provide part of the long-term immune protection that we need from vaccines.
If they are ever exposed to the pathogen in the future, special memory B cellsramp up antibody production.
Or in some cases, you might get a mild illness without severe symptoms.
Innate Immune Response
One of the challenges for vaccine developers is that theimmune systemis very complex.
Its not just B cells that respond when your body is infected or when its vaccinated.
Various parts of your innate immune system respond too.
Sometimes, these responses can also come into play when a person has been vaccinated.
Relatively Common Vaccine Side Effects
Side effects at the injection site are relatively common.
These might include pain, redness, and swelling.
Fainting is another not-infrequent side effect that sometimes occurs just after getting a vaccine.
Because of this, its standard to monitor adolescents for 15 minutes or so after giving these vaccines.
If you are feeling dizzy or lightheaded after getting a vaccine, stay seated and let someone know.
Having a little something to drink and eat can help.
The feeling should pass relatively soon.
Febrile Seizures
Febrile seizuresare an important complication that some children experience after a vaccine.
Although they are alarming, such seizures usually arent serious.
Children grow out of having these types of seizures, and they dont require long-term anti-seizure drugs.
They also dont increase a childs risk of death or cause any long-term neurological problems.
But they are more common after certain types of vaccines.
The newer version of the vaccine causes high fevers and febrile seizures much less commonly.
Who Gets Side Effects?
An example is an MMR vaccine given in childhood, used to preventmeasles, mumps, and rubella.
Your symptoms might not be related to vaccination.
Can I Take Medicines to Reduce Side Effect Symptoms?
You may wonder whether it is OK to take medicines for side effects like fever after a vaccination.
Your child may seem fussy and uncomfortable for a while, so its natural to want to help.
Or you may feel out of sorts yourself.
These often decrease side effect symptoms.
Theoretically, that might mean decreased protection.
Still, pain-relieving medications may be the right choice in some situations.
Vaccine Adverse Events
Serious vaccine adverse events are extremely rare.
Specific risks of these occurrences vary based on the vaccine.
Both MMR vaccines can also (extremely rarely) cause neurological issues such as encephalitis.
Another good example is therotavirusvaccine.
(Thats a serious disorder in which part of the intestine slides inside another part.)
Severe Allergic Reactions
A very rare potential adverse event from all vaccinations are allergic reactions.
In some cases, an allergic reaction might just cause mild symptoms, like a rash and itchy skin.
But sometimes allergic reactions can cause life-threatening swelling of the airway, causing difficulty breathing (anaphylaxis).
Symptoms of a severe allergic reaction usually occur within a few minutes to an hour of getting vaccinated.
Studying Vaccine Adverse Events
One of the challenges of studying vaccine adverse events is their rarity.
Because they are so rare, it can be difficult to determine exactly how common they are.
Another challenge is that sometimes, medical problems occur after a vaccination coincidentally.
The vaccine didnt have anything to do with the problem happening.
But the problem might be documented and go into the medical literature as an adverse event from a vaccine.
Also, getting the flu itself also increases ones risk of GBS.
So its not clear that getting vaccinated poses more risk overall.
Using the Vaccine Adverse Event Reporting System, individuals can submit information about potential adverse events related to vaccination.
For example, new versions of theflu vaccinemay be less likely to induce anaphylactic reactions compared to older versions.
That may be the price we have to pay for protective immunity.
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Smith DK, Sadler KP, Benedum M.Febrile seizures: Risks, evaluation, and prognosis.Am Fam Physician.
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