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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 

Original publication




Journal article



Publication Date





2298 - 2306


Controlled human infection challenge model, Influenza vaccination, Live attenuated influenza vaccine, Pneumococcal inoculation, Pneumococcus colonisation, Streptococcus pneumoniae, Symptoms, Adult, Coinfection, Double-Blind Method, Humans, Influenza Vaccines, Influenza, Human, Nasopharynx, Streptococcus pneumoniae, Time Factors, Vaccination, Vaccines, Attenuated, Vaccines, Inactivated