Investigations into human influenza transmission

摘要: Limited understanding of influenza transmission has been a frequent obstacle during the development pandemic infection prevention and mitigation strategies. The science is hotly debated, especially relative importance via large droplets or aerosols. Clarification different modes critical for refinement evidence-based control advice called by European Center Disease Control (ECDC), World Health Organization (WHO), US Institute Medicine. The primary aims this thesis were to investigate transmission; i) obtaining data concerning viral shedding presence virus in near environment infected individuals ii) through exploration human challenge model study transmission. Two major clinical studies have performed; • Shedding environmental deposition novel A (H1N1) virus. correlate amount detected subject’s nose with that recovered from his/her immediate (on surfaces air) symptom duration severity. Adults children, both hospital community, who had symptoms enrolled. Information about was collected samples taken including swabs, swabs air samples. Forty two subjects A(H1N1)pdm09 recruited followed up. mean nasal 6.2 days (by PCR) 4.6 culture). Over 25% cases remained potentially infectious at least 5 days. Symptom scores poorly correlated. From surface vicinity 40 subjects, 15 (38%) subject locations contaminated Overall 36 662 (5.4%) positive influenza, (0.3%) yielded viable Subjects yielding significantly higher loads on illness Day 3 more prominent respiratory scores. Room sampled 12 PCR obtained five (42%). Particles small enough reach distal lung (≤4µm) found contain • Use assess person-to-person transmission: Proof-of-concept study. aim establish an experimentally induced transmissible. Healthy deemed sero-susceptible A/H3N2/Wisconsin/67/2005 intranasally inoculated (Donors) when began, further (Recipients) exposed Donors ‘Exposure Event’. close contact, e.g. playing games eating meals together, total 28 hours 2 day period. Samples confirm status. Among 24 healthy adult nine randomised ‘Donor’ group ‘Recipient’ group. Following inoculation out 9 (55%) developed 7 (78%) proven be infected. After exposure, Recipients Three others non prior exposure. overall attack rate 20% but after adjustment pre-exposure immunity. The droplet aerosol routes are all likely role. This shows may less important than current policies public guidance documents imply. Air sampling results add accumulating evidence supports potential influenza. could used funded Centers (CDC) planned.