Symptoms associated with influenza vaccination and experimental human pneumococcal colonisation of the nasopharynx.
Hales C., Jochems SP., Robinson R., Solórzano C., Carniel B., Pojar S., Reiné J., German EL., Nikolaou E., Mitsi E., Hyder-Wright AD., Hill H., Adler H., Connor V., Zaidi S., Lowe C., Fan X., Wang D., Gordon SB., Rylance J., Ferreira DM.
BACKGROUND: Nasopharyngeal colonisation by S. pneumoniae is a prerequisite for invasive pneumococcal infections. Influenza co-infection leads to increased susceptibility to secondary pneumonia and mortality during influenza epidemics. Increased bacterial load and impaired immune responses to pneumococcus caused by influenza play a role in this increased susceptibility. Using an Experimental Human Challenge Model and influenza vaccines, we examined symptoms experienced by healthy adults during nasal co-infection with S. pneumoniae and live attenuated influenza virus. METHODS: Randomised, blinded administration of Live Attenuated Influenza Vaccine (LAIV) or Tetravalent Inactivated Influenza Vaccine (TIV) either preceded bacterial inoculation or followed it, separated by a 3-day interval. The presence and density of S. pneumoniae was determined from nasal washes. Participants completed a symptom questionnaire from the first intervention until 6 days post second intervention. RESULTS: The timing and type of influenza vaccination and presence of S. pneumoniae in the nasopharynx significantly affected symptom reporting. In the study where influenza vaccination preceded bacterial inoculation: nasal symptoms were less common in the LAIV group than the TIV group (OR 0.57, p