Administering Influenza Vaccine to Patients with Human Immunodeficiency Virus (HIV): Does Timing Matter?
Session: Poster Abstract Session: HIV: Comorbidities and Coinfections
Saturday, October 11, 2014
Room: The Pennsylvania Convention Center: IDExpo Hall BC
Background: Researchers have developed methods to predict the magnitude, timing, intensity and duration of the upcoming influenza season largely based on data from previous years. The Centers for Disease Control and Prevention (CDC) records peak months of flu activity annually. In recent flu seasons, the incidence of flu did not start to dramatically increase until mid-December. In the U.S., influenza risk is low in September and October, but begins to increase toward the end of November. The highest risk typically occurs from January through March. It takes 2-4 weeks to develop peak antibody titers after influenza vaccination. In the general population, once immunity to influenza has been acquired, it begins to wane over time. Patients who have human immunodeficiency virus (HIV) are at risk for rapid decline in protective immunity to influenza, thus rendering them more susceptible to influenza infection. It is known that antibody titers wane over time, but it is unclear if timing of influenza vaccination within the flu season affects the probability of an influenza infection later during the flu season. This retrospective analysis will explore the relationship between the occurrence of flu or influenza-like illness in HIV patients and the time after influenza vaccine was administered.
Methods: A retrospective chart review was conducted at VA San Diego Healthcare Systems from September 1, 2005 to May 31, 2013. Patients with laboratory confirmed influenza, diagnosed with influenza by a physician, or who retrospectively met criteria for influenza like illness (ILL) were included. Specific criteria for ILL included: fever (T > 100°F) and cough or sore throat in the absence of any other known cause.
Results: A total of 1176 patients were screened. If vaccinated early (n=2773) (9/1-11/15) vs. late (=1802) (on or after 11/16) there was a higher incidence of flu, 30/2773 (1.1%) vs. 7/1802 (0.4%), p=0.0105. Vaccinated patients who developed flu were more likely to have symptoms later in the season (on or after 1/16) 26/37 (70%) vs. 11/37 (30%), p=0.0094.
Conclusion: The results of this study can provide insight and guidance on timing and administration of influenza vaccination administration in HIV patients.
Elizabeth R. Glinka, Pharm.D., BCPS and Scott T. Johns, PharmD, BCPS, Veterans Affairs San Diego Healthcare System, San Diego, CA