Share this article on:

Evidence of Homosubtypic But Not Heterosubtypic Immunity in Young Children Following Wild-type Influenza Illness

Ambrose, Christopher S. MD*; Wu, Xionghua PhD

The Pediatric Infectious Disease Journal: October 2011 - Volume 30 - Issue 10 - p 900-901
doi: 10.1097/INF.0b013e31821ffe43
Brief Reports

The effect of subtype-specific influenza illness in young children on the probability of influenza illness in the following year was analyzed for placebo recipients in four 2-year vaccine efficacy studies. There was evidence of homosubtypic protection but no evidence of heterosubtypic protection; however, a moderate-to-low level of heterosubtypic protection could not be ruled out. This analysis supports previous observations that children do not develop lasting, clinically significant heterosubtypic protection after influenza illness.


From *Medical and Scientific Affairs and †Biostatistics, MedImmune, LLC, Gaithersburg, MD.

Accepted for publication April 13, 2011.

Supported by MedImmune.

Both authors are employees of MedImmune, LLC, Gaithersburg, MD.

The authors have no other funding or conflicts of interest to disclose.

Address for correspondence: Christopher S. Ambrose, MD, Medical and Scientific Affairs, MedImmune, LLC, One MedImmune Way, Gaithersburg, MD 20878. E-mail:

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Web site (

© 2011 Lippincott Williams & Wilkins, Inc.