(S (S (BASENP (DT The) (NNP WHO)) (VP (VBZ says) (SBAR (IN that) (S (NP (BASENP (JJ many)) (PP (IN of) (NP (BASENP (DT the) (JJ severe) (NNS cases)) (PP (IN of) (BASENP (DT the) (NN virus)))))) (VP (VBP are) (VP (VBN reported) (PP (IN in) (NP (BASENP (NNS people)) (PP (IN with) (BASENP (JJ prior) (JJ chronic) (NNS illnesses))))))))))) (PERIOD .))