Abstract
Objectives: The World Health Organization (WHO) has announced a pandemic alert following successive waves of H1N1 epidemics that have swept the world. KSA became vulnerable to influenza virus due to Hajj and Umrah pilgrimages. Antibodies have been tested to inhibit the attachment and spread of influenza viruses to epithelial cells. This study aimed to assess the immunological indices of the influenza vaccine, VAXIGRIP, in triggering humoural immunity in volunteers.
Methods: Sera from pre- and 14 days post-vaccinated subjects were analysed for haemagglutinin (HA)-specific anti-H1 and anti-H3 antibodies using ELISA. Expansion of CD19(+) B cells was quantified using FACSCalibur.
Results: The VAXIGRIP vaccine induced specific anti-H1 and anti-H3 HA IgG antibodies against H1N1 and H3N2 influenza viruses, respectively. There was a significant increase in B cell numbers post-vaccination that directly matched the anti-H1 antibody titre. The results suggest that B cells are likely to be primed by the same antigenic strain derived from both H1N1 and H3N2 viruses, which were likely to be included in the vaccine.
Conclusion: Influenza vaccine triggered a humoural immune response to surface HA proteins in vaccinated subjects. To our knowledge, this is the first report corroborating the immunogenicity of the influenza vaccine in KSA volunteers. These results may be beneficial to the ministry of health and the Saudi FDA in terms of weighing the role of this vaccine in inducing protective immunity.