Effectiveness of ten-valent pneumococcal conjugate vaccine on invasive pneumococcal disease among children <2 years old: A prospective population-based study in rural Bangladesh.

The 10-valent pneumococcal conjugate vaccine (PCV10) was introduced in March 2015 in Bangladesh. In this study, we aimed to estimate the impact of PCV10 on invasive pneumococcal disease (IPD) identified by blood cultures and severe pneumonia identified clinically and its effectiveness on invasive disease caused by vaccine serotypes. We conducted population-based surveillance among children aged 2- <24 months between April 2012 through March 2019 in Mirzapur, a rural sub-district of Bangladesh. We compared incidence of IPD and severe pneumonia before (April 2012 to March 2015) and after (April 2015 to March 2019) the introduction of PCV10. Vaccine effectiveness was measured using an indirect cohort analysis of data from four sentinel sites in which PCV10 vaccination status was compared between children with IPD caused by vaccine serotype vs. non-vaccine serotypes. We identified 24 IPD cases by blood culture and 1,704 severe pneumonia hospitalizations during the surveillance period. IPD incidence in under-2-year-old children fell 25 % (95 % CI: -1.2 % to 76 %; p-value = 0.59) from 106 cases per 100,000 child-years at baseline to 79.3 in April 2018- March 2019. Vaccine serotype-IPD incidence was lower (77 % reduction, 95 % CI: -0.45 % to 96 %; p-value = 0.068) in April 2018 - March 2019 than in the pre-vaccine period (85.7 cases to 19.8/100,000 child-years). A significant decline of 54.0 % (95 % CI: 47.0 % to 59.0 %; p-value < 0.001) was observed in hospitalizations due to severe pneumonia. From indirect cohort analysis, the effectiveness of PCV10 against vaccine serotype IPD was 37 % (95 % CI: -141.0 % to 83.5 %; p = 0.5) after the 1st dose and 63.1 % (95 % CI: -3.3 % to 85.9 %, p = 0.0411) after the 2nd or the 3rd dose. This study demonstrates that PCV10 introduction prevented hospitalizations with severe pneumonia and provided individual protection against vaccine serotypes.

Prevalence of group B Streptococcus colonisation in mother-newborn dyads in low-income and middle-income south Asian and African countries: a prospective, observational study.

BACKGROUND: Rectovaginal group B Streptococcus (GBS) colonisation in pregnant individuals at the time of labour is a major risk factor for invasive GBS disease by age 7 days (early-onset disease). We aimed to investigate the prevalence of rectovaginal GBS colonisation at the time of labour among pregnant women and vertical transmission to their newborns across selected low-income and middle-income African and south Asian countries. METHODS: This prospective, observational study was undertaken at 11 maternity and obstetric care facilities based in Ethiopia, Kenya, Mozambique, Nigeria, Mali, South Africa, Bangladesh, India, and Bhutan. HIV-negative pregnant women aged 18-45 years who were in the early stages of labour and at least 37 weeks' gestation were eligible for inclusion. Lower vaginal and rectal swabs and urine were collected from the women, and swabs of the umbilicus, outer ear, axillary fold, rectum, and throat were obtained from their newborns, for GBS culture. Standardised sampling and culture using direct plating and selective media broth for detection of GBS colonisation was undertaken at the sites. Serotyping of GBS isolates was done in South Africa. The primary outcome was the prevalence of rectovaginal GBS among pregnant women, analysed in participants with available data. This study is registered with the South African National Clinical Trials Register, number DOH-27-0418-4989. FINDINGS: 6922 pregnant women were enrolled from Jan 10, 2016, to Dec 11, 2018, of whom 6514 (94·1%; 759-892 per country) were included in the analysis; data from Bhutan were not included in the study due to issues with specimen collection and processing. Overall, the prevalence of maternal GBS colonisation was 24·1% (95% CI 23·1-25·2; 1572 of 6514); it was highest in Mali (41·1% [37·7-44·6]; 314 of 764) and lowest in Ethiopia (11·6% [9·5-14·1]; 88 of 759). The overall rate of vertical transmission of GBS from women with rectovaginal GBS colonisation was 72·3% (70·0-74·4; 1132 of 1566); it was highest in Mozambique (79·2% [73·3-84·2]; 168 of 212) and lowest in Bangladesh (55·8%, 47·5-63·8; 77 of 138). The five most common GBS colonising serotypes were Ia (37·3% [34·9-39·7]; 586 of 1572), V (28·5% [26·3-30·8]; 448 of 1572), III (25·1% [23·0-27·3]; 394 of 1572), II (9·2% [7·8-10·7]; 144 of 1572), and Ib (6·5% [5·4-7·8]; 102 of 1572). There was geographical variability in serotype proportion distribution; serotype VII was the third most common serotype in India (8·6% [5·3-13·7]; 15 of 174) and serotype VI was mainly identified in Bangladesh (5·8% [3·0-11·0]; eight of 138) and India (5·7% [3·2-10·3]; ten of 174). INTERPRETATION: Our study reported a high prevalence of GBS colonisation in most settings, with some geographical variability even within African countries. Our findings suggest that serotypes not included in current multivalent capsular-polysaccharide GBS vaccines prevail in some regions, so vaccine efficacy and post-licensure effectiveness studies should assess the effect of vaccination on maternal GBS colonisation given the potential for replacement by non-vaccine serotypes. FUNDING: Bill & Melinda Gates Foundation.