An Unimmunized Young Adult: What Now?

September 16, 2016

The patient is 19, was home-schooled, and is referred to primary care by the local emergency department. Where to start?

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A 19-year-old male is referred to your office for further immunizations from your local emergency department. Twenty-one days ago he presented there with a dog bite wound and a history of no previous immunizations. He received a dose of human tetanus immune globulin (TIG) along with a Td shot. His parents didn't “believe” in vaccines when he was a child and he had been home schooled. He moved out of his parents household 6 months ago and is planning to start community college part time and was told he would need to get immunized to enroll. He denies having had any childhood illness other than whooping cough at age 3. He is sure he never had chickenpox or measles. He also wants you to look at an itchy, slightly painful rash on his back. On examination, he has a classic case of shingles.

A few questions present themselves. You first address the one around Td/Tdap.

Which of the following is the correct approach?

A. You administer a Tdap today and have him return in 6 months for a Td.

B. He needs 2 more Td doses, but having had pertussis does not need a Tdap

C. It's too early to give the second Td or Tdap; 8 weeks is the recommended minimum time between doses 1 and 2 of this series  

D. Since he got TIG, you will need to wait 3 months before the next Td/Tdap since the TIG will interfere with the immune response to the vaccine.

E. None of the above are correct    

Please click here for answer, discussion, and next question.


The correct answer is E. None of the options is correct.

Pertussis immunity is not lifelong after natural infection so he does need a Tdap. The minimum time between doses 1 and 2 is 4 weeks, so he needs to wait at least another week before the second one. Generally speaking, it is not a problem immunologically to have extra time between doses, but if a dose is given before the recommended minimum time, it will have to be repeated. Option D is incorrect since the response to non-live vaccines is not affected by immune globulin, unlike live vaccines. This young man should return in one week for a Tdap and then 6 months after that for a Td.


Next: What do you do about the MMR vaccine?

A. Give a single dose now. Unlike a child, adults do not need a second dose.

B. Give a dose now and in 4 weeks since he will be attending a post-secondary school

C. Wait 3 months after the dose of TIG since the immune globulin can blunt the immune response to the MMR.

D. Wait 6 months after the dose of TIG since the immune globulin can blunt the immune response to the MMR.

Please click here for answer, discussion, and next question.


The correct answer is: C. Wait 3 months after the dose of TIG...

Previously unimmunized adults only need one dose of MMR unless they work in a health care facility, are attending a post-secondary school, or plan to travel internationally. TIG is not a monoclonal antibody, so is assumed to have some anti=measles antibody present and The RED BOOK published by the AAP recommends a 3-month interval between TIG and MMR administration.


Finally, which of the following statements about varicella vaccine administration in this case is/are true?

A. He doesn't need it, ever.

B. Immune globulin administration does not impact the decision to administer the varicella vaccine.

C.  He should receive a dose 3 months after the TIG was given and a second dose 8 weeks after that.

D. Both A and B are true

Please click here for answer and discussion.


    T    he correct answer is D. Both A and B are true

One is considered immune to varicella if any of the following is true:  you were born in the US before 1980; previously had a health care provider diagnosis of varicella or shingles; had 2 doses of vaccine given appropriately; or have lab evidence of immunity. Unlike measles, immune globulin has not conclusively been shown to interfere with the immune response to varicella vaccine administration, so both answers A and B are correct.



The current adult recommended vaccine schedule.

The RED BOOK, 2015. Gives information on immune globulin administration and the impact on measles and varicella vaccine administration.