(S (S (NP (BASENP (DT An) (JJ extensive) (NN vaccination) (NN campaign)) (PP (IN across) (NP (NN 19) (NP (ADJP (ADJP (JJ West) (CC and) (JJ Central)) (JJ African)) (NNS countries))))) (VP (VBZ is) (S (VP (TO to) (VP (VP (VB begin) (BASENP (NN today))) (PP (IN in) (NP (BASENP (DT an) (NN attempt)) (SBAR (S (VP (TO to) (VP (VP (VB stem) (BASENP (DT a) (JJ year-long) (NN polio) (NN epidemic))) (PP (IN in) (BASENP (DT the) (NN region)))))))))))))) (PERIOD .))