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Li A, Kärnell A, Huan PT, Cam PD, Minh NB, Trâm LN, Quy NP, Trach DD, Karlsson K, Lindberg G, et al.Li A, et al. Among authors: karnell a.Vaccine. 1993;11(2):180-9. doi: 10.1016/0264-410x(93)90015-p.Vaccine. 1993.PMID: 8438616Clinical Trial.