Q:

9/17/2013
I am doing the immunologic lab work-up for a patient (2 year-old boy with history of recurrent otitis media); he had labs drawn last week (September 10) and after labs were drawn he had Pneumovax given. I learned from the lab today that they missed putting in the order for the pre-vaccination pneumococcal antibody titers; hopefully the lab where the blood was sent will be able to add pre-vaccination pneumococcal antibody titers to the blood which was already drawn. If in case the lab can’t be added to blood already drawn, is there any value in checking the pneumococcal antibody titers now and then checking 5 weeks later? I don’t know how much the titers would have changed in 1 week after vaccination. Assuming that the lab can’t be added to the blood which was already drawn last week, when is the latest that the titers can be drawn so that I can still have an initial set of titers to compare the later titers to? Thanks as always for your helpful input!

A:

Thank you for your inquiry.

As you know, the maximum antibody titer after immunization with Pneumovax usually is reached by four weeks. It is possible that, should you redraw blood now, you might therefore see a significant rise in the intervening two to three weeks you have before the maximum titer is normally reached. I would therefore redraw the titers as soon as feasible.

You also, of course, would be able to assess whether this child was reacting normally by assessing the number of antigens showing a protective level of anti-pneumococcal titers. A protective or adequate response to a pneumococcal polysaccharide serotype is defined as a titer of 1.3 mcg/ml or higher. In a child from 24 months to 5 years of age, this protective level should be present in at least 50% of the serotypes evaluated (1).

Thank you again for your inquiry and we hope this response is helpful to you.

Reference:
1.Ballow M. Use of vaccines in the evaluation of presumed immunodeficiency. Annals of Allergy, Asthma, and Immunology 2013 (September); 111(3):163-166.

Sincerely,
Phil Lieberman, M.D.

AAAAI - American Academy of Allergy Asthma & Immunology