Re-emergence of pneumococcal colonization by vaccine serotype 19F in persons aged ≥5 years after 13-valent pneumococcal conjugate vaccine introduction-Alaska, 2008-2013.

•Pneumococcal conjugate vaccines (PCV) protect against serotype 19F.•Serotype 19F colonization and disease decreased after PCV introduction in 2001.•We observed an increase in serotype 19F colonization in Alaska since 2008.•Serotype 19F re-emergence corresponded with the introduction of a new genotype.•The new 19F genotype might be less susceptible to PCV.