(S (S (BASENP (DT The) (NNP H1N1) (NN virus)) (VP (VP (VBZ differs) (PP (IN from) (NP (BASENP (DT the) (JJ normal) (JJ seasonal) (NN flu)) (SBAR (WHPP (IN in) (WHNP (WDT that))) (S (BASENP (PRP it)) (VP (VBZ has) (VP (VBN persisted) (PP (IN during) (BASENP (DT the) (NN summer) (NNS months)))))))))) (CC and) (VP (VBD affected) (NP (BASENP (ADJP (RB relatively) (JJ healthy)) (NNS people)) (PP (IN under) (NP (BASENP (DT the) (NN age)) (PP (IN of) (BASENP (NN 65))))))))) (PERIOD .))