Vaccines work and they work very well.
Unfortunately, they don’t work 100% of the time.
A breakthrough infection is the term for when you get sick despite having been vaccinated and responding to the vaccine.
On the plus side, breakthrough infections are typically much milder than what you would have gotten if you were unvaccinated.
For example, compared to chicken pox in an unvaccinated child, breakthrough chicken pox:
- causes fewer chicken pox lesions (less than 50 lesions vs 200 to 500 lesions)
- goes away faster (4 to 6 days vs at least 7 days)
- has less or no fever
- is less contagious
And that’s just another good reason to get vaccinated.
For more information:
- Ask the Experts: Chickenpox (varicella)
- ACIP – Prevention of Varicella
- Why do we continue to use vaccines that are not 100% effective?
- Vaccine Effectiveness – How Well Does the Flu Vaccine Work?