Pneumococcal Conjugate Vaccine Impact on Meningitis and Pneumonia Among Children Aged <5 Years-Zimbabwe, 2010-2016.

BACKGROUND: Streptococcus pneumoniae is a leading cause of pneumonia and meningitis in children aged <5 years. Zimbabwe introduced 13-valent pneumococcal conjugate vaccine (PCV13) in 2012 using a 3-dose infant schedule with no booster dose or catch-up campaign. We evaluated the impact of PCV13 on pediatric pneumonia and meningitis. METHODS: We examined annual changes in the proportion of hospitalizations due to pneumonia and meningitis among children aged <5 years at Harare Central Hospital (HCH) pre-PCV13 (January 2010-June 2012) and post-PCV13 (July 2013-December 2016) using a negative binomial regression model, adjusting for seasonality. We also evaluated post-PCV13 changes in serotype distribution among children with confirmed pneumococcal meningitis at HCH and acute respiratory infection (ARI) trends using Ministry of Health outpatient data. RESULTS: Pneumonia hospitalizations among children aged <5 years steadily declined pre-PCV13; no significant change in annual decline was observed post-PCV13. Post-PCV13 introduction, meningitis hospitalization decreased 30% annually (95% confidence interval [CI], -42, -14) among children aged 12-59 months, and no change was observed among children aged 0-11 months. Pneumococcal meningitis caused by PCV13 serotypes decreased from 100% in 2011 to 50% in 2016. Annual severe and moderate outpatient ARI decreased by 30% (95% CI, -33, -26) and 7% (95% CI, -11, -2), respectively, post-PCV13 introduction. CONCLUSIONS: We observed declines in pediatric meningitis hospitalizations, PCV13-type pneumococcal meningitis, and severe and moderate ARI outpatient visits post-PCV13 introduction. Low specificity of discharge codes, changes in referral patterns, and improvements in human immunodeficiency virus care may have contributed to the lack of additional declines in pneumonia hospitalizations post-PCV13 introduction.

Enhanced surveillance for adverse events following immunization during the 2019 typhoid conjugate vaccine campaign in Harare, Zimbabwe.

BACKGROUND: During February 25-March 4, 2019, Zimbabwe's Ministry of Health and Child Care conducted an emergency campaign using 342,000 doses of typhoid conjugate vaccine (TCV) targeting individuals 6 months-15 years of age in eight high-risk suburbs of Harare and up to 45 years of age in one suburb of Harare. The campaign represented the first use of TCV in Africa outside of clinical trials. METHODS: Three methods were used to capture adverse events during the campaign and for 42 days following the last dose administered: (1) active surveillance in two Harare hospitals, (2) national passive surveillance, and (3) a post-campaign coverage survey. RESULTS: Thirty-nine adverse events were identified during active surveillance, including 19 seizure cases (16 were febrile), 16 hypersensitivity cases, 1 thrombocytopenia case, 1 anaphylaxis case, and two cases with two conditions. Only 21 (54%) of 39 patients were hospitalized and 38 recovered without sequelae. Attack rates per 100,000 TCV doses administered were highest for seizures (6.27) and hypersensitivity (5.02). Only 6 adverse events were reported through passive surveillance by facilities other than the two active surveillance hospitals. A total of 177 (10%) of 1,817 vaccinees surveyed reported experiencing an adverse event during the post-campaign coverage survey, of which 25 (14%) sought care. CONCLUSIONS: In line with previous evaluations of TCV, enhanced adverse event monitoring during an emergency campaign supports the safety of TCV. The majority of reported events were minor or resulted in recovery without long-term sequelae. Attack rates for seizures and hypersensitivity were low compared with previous active surveillance studies conducted in Kenya and Burkina Faso. Strengthening adverse event monitoring in Zimbabwe and establishing background rates of conditions of interest in the general population may improve future safety monitoring during new vaccine introductions.