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It is reported that the H1N1 wild strain till now does not transmit via close contact between people to people but the experimentally mutated strain does, which was reported by a Nerthland and a US group respectively. Why? It is very trying to deduce from theoretical hypothesis as the droplet containing the wild type H1N1 if being breathed by an otherwise healthy people from an infected patient. Why does not that cause the H1N1 infection but just contact from diseased birds?