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Do You Ever Have to Restart an Immunization Series?

With all of the rules for minimum and recommended ages and intervals between doses of vaccines, if you are late with a dose of a vaccine by a few extra days, months, or years, what happens?

Fortunately, we rarely have to restart an immunization series because of a late dose of a vaccine.
Fortunately, we rarely have to restart an immunization series because of a late dose of a vaccine.

Do you ever have to start the series over?

Do You Ever Have to Restart an Immunization Series?

While it is best to follow the recommend schedule when you get your vaccines, fortunately, you usually don’t have to restart an immunization series if you are a little late.

“Q. If a dose of HPV vaccine is significantly delayed, do I need to start the series over?
A. No, do not restart the series. You should continue where the patient left off and complete the series.”

Ask the Experts about HPV Vaccines

Or even a lot late!

“Q. If dose #1 of HPV vaccine was given before the 15th birthday and it has been more than a year since that dose was given, would the series be complete with just one additional dose?
A. Yes. Adolescents and adults who started the HPV vaccine series prior to the 15th birthday and who are not immunocompromised are considered to be adequately vaccinated with just one additional dose of HPV vaccine.”

Ask the Experts about HPV Vaccines

In fact, very rarely would you need to repeat a dose or restart a series of immunizations because of a late dose of a vaccine.

“Prolonged intervals between doses do not appear to diminish and may enhance antibody response to 4vHPV.”

Widdice et al on Antibody responses among adolescent females receiving two or three quadrivalent human papillomavirus vaccine doses at standard and prolonged intervals

And that’s good news, as it is sometimes hard to get folks to complete their immunization series on time.

When You Have to Restart an Immunization Series

There are a few very specific times when a late dose of a vaccine would lead to the need to restart an immunization series though, including the:

  • oral typhoid vaccine – if the interruption between doses is less than 21 days, you can resume the schedule without repeating previous doses, but if the interruption is more than 21 days, then you should repeat the series of vaccines
  • cholera vaccine (Dukoral only) – if the interval between doses is greater than or equal to six weeks, then you should restart the series

So if you are even a little late getting a dose of oral typhoid or cholera vaccine, then you might have to start the series over. In most other situations, you just continue the series from where you left off, even if it has been years since your last dose.

What about the rabies vaccine?

“If any doses are delayed, vaccination should be resumed, not restarted.”

Rabies vaccines: WHO position paper – April 2018

Although you don’t have to restart the series if you are late with a dose, the CDC does recommend serologic testing 7-14 days after the last dose of rabies vaccine if there are “substantial deviations” to the schedule.

Again, in most other situations, including all of the vaccines on the routine immunization schedule, you just catch-up and continue from where you left off if you are late getting a vaccine dose.

More on Late Doses of Vaccines

1 thought on “Do You Ever Have to Restart an Immunization Series?”

  1. Pingback: Catch-Up Immunization Schedules - VAXOPEDIA

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