INSIGHTS INTO ANTIBODY AND T-CELL MEDIATED IMMUNITY TO INFLUENZA FROM POPULATION-BASED COHORT STUDIES

Abstract

INFLUENZA VACCINES INDUCE VIRUS-SPECIFIC ANTIBODIES TO PROTECT AGAINST INFECTION. HOWEVER, THE DECLINE OF ANTIBODY OVERTIME INCREASES THE NEED FOR DEVELOPING VACCINE THAT ELICIT CYTOTOXIC T-CELL IMMUNITY. THE OBJECTIVES ARE TO INVESTIGATE: 1)THE TRAJECTORY OF ANTIBODY DECLINE FOLLOWING SEROCONVERSION TO A(H1H1)PDM09; 2)THE ROLE OF PRE-EXISTING T-CELL IMMUNITY TO A/SINGAPORE/CDC204/2012(H3N2) IN PROTECTING AGAINST SUBSEQUENT INFLUENZA INFECTIONS. IN CHAPTER 2, THE DECLINE WAS ASSESSED WITH A COHORT WHO PREVIOUSLY SEROCONVERTED TO A(H1N1)PDM09 (N=67). PROPORTION OF SERO-POSITIVITY (HI=40) DECREASED SIGNIFICANTLY FROM 71% TO 25% AFTER SIX MONTHS, AND IS MORE SIGNIFICANT IN ELDERLY. IN CHAPTER 3, THE PROTECTIVE EFFECT OF PRE-EXISTING T-CELL IMMUNITY TOWARDS A/SINGAPORE/CDC204/2012(H3N2) ON SUBSEQUENT INFLUENZA INFECTIONS WAS ASSESSED WITH A COMMUNITY COHORT (N=507). A SIGNIFICANT PROTECTIVE EFFECT WAS OBSERVED FOR BOTH SYMPTOMATIC AND ASYMPTOMTIC INFECTIONS; AND WAS MORE EVIDENT IN P