An outbreak may pertain-to a (flu virus).Logical formLearned from16 sentences. A (bird flu strain) may infect humans.Logical formLearned from16 sentences. Flu may be knowned.Logical formLearned from16 sentences. A vaccine can be against a flu.Logical formLearned from16 sentences. Shortages can be constituted-of-or-filled-with (flu vaccine).Logical formLearned from16 sentences. A (flu vaccine) may pertain-to a person.Logical formLearned from16 sentences. Varieties can be constituted-of-or-filled-with flu.Logical formLearned from16 sentences. A flu can be a respiratory illness.Logical formLearned from16 sentences. (Bird flu) may start.Logical formLearned from16 sentences. A victim may pertain-to a flu.Logical formLearned from16 sentences. Information can be on avian flu.Logical formLearned from16 sentences. (Health officials) may confirm some cases of flu.Logical formLearned from16 sentences. A combination may pertain-to a flu.Logical formLearned from16 sentences. Schools may close (flu cases).Logical formLearned from16 sentences. Tests may confirm some cases of flu.Logical formLearned from16 sentences.