The typical question I am asked is along the lines of, "He is due for his 4 month shots on July 5th, but we are on vacation. Is it okay to wait until the end of July?"
"Tweeny is getting her first HPV vaccine today, but she has a big out of town tournament the week she is due for the 2nd dose. Can she come later?"
The answer to both questions: yes.
Vaccines are recommended with minimal intervals (you can't give them too soon) but if there is a delay for whatever reason (missed appointments, scheduling conflicts, immune compromise-such as cancer in a child or their caregiver) it is recommended to catch up as soon as possible. Doses do not need to be repeated if the interval has been longer than recommended.
Conversely, it is not appropriate in most cases to give vaccines at shorter intervals or before the recommended age.
The 12-15 month vaccines are occasionally given before the 1st birthday, which does not count in Kansas. Some states have a leeway for giving doses early, but Kansas does not. This is an issue with some children moving to our state from a more lenient state. Maybe they get their MMR a couple days before their first birthday. Does this protect them against measles, mumps, and rubella? Probably. Does the school count it? No. They need to repeat it.
Another scenario is children traveling outside the US. It is recommended for international travelers over 6 months to get an MMR early due to worldwide outbreaks. This dose does not count toward the 2 doses typically given because younger children do not make immunity as reliably, but is felt to potentially benefit those at higher risk due to travel.
Another common scenario involves Hepatitis A and B vaccines due to the ages given and the intervals required.
The dosing interval for Hepatitis A is a minimum of 6 months. We typically give it at 12 months and 18 months, but if these appointments are scheduled with less than 6 months between, we typically wait until the 24 month visit to do the 2nd Hepatitis A vaccine. This delay is okay.
Hepatitis B vaccine is given in 3 doses, with the second 4 weeks after the first, then the 3rd at least 8 weeks from the 2nd and 16 weeks after the 1st. If a newborn does not get the first Hepatitis B vaccine on the date of birth for whatever reason (too ill, parental preference, prematurity) and the one month well check is less than 28 days from the first dose, we delay the 2nd Hepatitis B vaccine until a future visit. This will push the 3rd dose back in most cases.Each year the CDC updates the recommended vaccine schedule. We know it is confusing to parents, but we will help keep your kids on track!