Pneumococcus serotypes in pre and post 13-valent polysaccharide conjugate vaccine era: Epidemiology in a pediatric intensive care unit over 10 years

Aim: Pneumococcus is a common commensal and an important pathogen among children for which immunization is available. Some serotypes occasionally cause severe pneumococcal disease (SPD) with high mortality and morbidity. We reviewed all pneumococcal serotypes and mortality/morbidity in a pediatric intensive care unit (PICU) following universal pneumococcal conjugate vaccine (PCV) immunization. Methods: A 13-valent PCV was introduced in the universal immunization program in late 2011 in Hong Kong. We retrospectively reviewed all pneumococcal serotypes in the pre-(2007-2011) and post-(2012-2016) 13-valent PCV era. Results: There were 29 (1.9%) PICU patients with pneumococcal isolation, and 6 of them died (20% motality). Serogroups 6 and 19 predominated before and serogroup- 3 after 2012. In the post 13-valent PCV era, the prevalence of pneumococcus isolation in PICU was increased from 1% to 2% (p=0.04), serogroup 3 was the major serotype of morbidity despite supposedly under vaccine coverage. The majority of pneumococcus were penicillin-sensitive (94%) in the post 13-valent PCV era.Binary logistic regression showed that there were reductions of serogroup 6 (odds ratio [OR], 0.050; 95% confidence interval [CI], 0.004-0.574; P = 0.016) and serogroup 19 (odds ratio [OR], 0.105; 95% confidence interval [CI], 0.014-0.786; P = 0.028), but not mortality or morbidity for patients admitted after 2012. Conclusions: SPD is associated with significant morbidity and mortality despite treatment with systemic antibiotics and ICU support. The expanded coverage of 13-valent PCV results in the reduction of serotype 6 and 19 but not mortality/morbidity associated with SPD in the setting of a PICU