Epidemiology of childhood invasive pneumococcal disease in Australia: a prospective cohort study

Background The widespread use of pneumococcal conjugate vaccines (PCV) has changed the epidemiology of invasive pneumococcal disease (IPD) in children globally. Methods Multicentre prospective audit of IPD episodes from five paediatric hospitals in Australia over 5.5 years between 2016 and June 2021. Children (<18 years) with Streptococcus pneumoniae isolated from a sterile site were included. Results There were 377 IPD episodes in 375 children: 338 (90%) had received >= 3 PCV doses; 42 (11%) had IPD risk factors. The most common presentations were complicated pneumonia (254, 67%), bacteraemia (65, 17%) and meningitis (29, 8%). Five (1%) children died. Serotype information was available for 230 (61%) episodes; 140 (61%) were 13vPCV vaccine serotypes (VTs). The majority (85%) of episodes of complicated pneumonia were due to a VT; predominantly 3, 19A, 19F. Children with risk factors were more likely to present with bacteraemia +/- sepsis (42% vs 12%) and to have a non-vaccine serotype (NVT) (74% vs 32%). Resistance to ceftriaxone (meningitis cut-off) occurred in 17% of 23B isolates (n=12) and accounted for 22% (5/23) of meningitis cases. Results There were 377 IPD episodes in 375 children: 338 (90%) had received >= 3 PCV doses; 42 (11%) had IPD risk factors. The most common presentations were complicated pneumonia (254, 67%), bacteraemia (65, 17%) and meningitis (29, 8%). Five (1%) children died. Serotype information was available for 230 (61%) episodes; 140 (61%) were 13vPCV vaccine serotypes (VTs). The majority (85%) of episodes of complicated pneumonia were due to a VT; predominantly 3, 19A, 19F. Children with risk factors were more likely to present with bacteraemia +/- sepsis (42% vs 12%) and to have a non-vaccine serotype (NVT) (74% vs 32%). Resistance to ceftriaxone (meningitis cut-off) occurred in 17% of 23B isolates (n=12) and accounted for 22% (5/23) of meningitis cases. Conclusions Complicated pneumonia is the most common IPD presentation. NVTs account for the majority of bacteraemia and meningitis episodes. High rates of ceftriaxone resistance for NVT 23B support the addition of vancomycin for empiric treatment of suspected meningitis.