When injectable vaccine volume is lost (patient moves, syringe leaks), it may be difficult to judge how much vaccine the patient actually received. Use your discretion to determine whether an adequate dose was given. In general, you should treat this as a nonstandard injectable dose and should not count it. If it was an inactivated vaccine, you should re-immunize the person as soon as possible. In the case of Shingrix (RZV; GSK) if the person is still in the office the dose can be repeated immediately; however, if the repeat Shingrix dose cannot be given on the same day CDC recommends that it should be given 4 weeks after the invalid dose.
If it was a live vaccine, you can give another dose if you detect the error on the same clinic day; otherwise, you should wait 28 days to give the next dose. However, if part of a dose of an oral vaccine (rotavirus) was spit out by an infant, count the dose and do not administer a second dose. If a person sneezes after live attenuated influenza vaccine (Flumist; AstraZeneca) the dose can be counted as valid.