National Center for Biotechnology Information NCBI NLM MEDLINE humans pubmed abstract nih national institutes of health national library of medicine research support u.s. gov't non-p.h.s. adult N.I.H. Extramural Infant P.H.S. Incidence population surveillance vaccines pneumococcal infections / epidemiology* pneumococcal infections / microbiology penicillin resistance hiv infections / complications streptococcus pneumoniae / classification south africa / epidemiology conjugate pmid:25386897 doi:10.1056/nejmoa1401914 anne von gottberg linda de gouveia germs-sa investigators heptavalent pneumococcal conjugate vaccine pneumococcal infections / prevention & control pneumococcal vaccines* / administration & dosage serogroup