Fractional Doses of Pneumococcal Conjugate Vaccine - A Noninferiority Trial.

BACKGROUND: Pneumococcal conjugate vaccines are an expensive component of the routine immunization schedule. Fractional-dose regimens may be one option to increase the sustainability of the vaccine program. METHODS: We assessed whether the immunogenicity of fractional doses of the 10-valent and 13-valent pneumococcal conjugate vaccines (PCV10 [GSK] and PCV13 [Pfizer], respectively) would be noninferior to that of the full doses and analyzed the prevalence of vaccine-serotype carriage. We randomly assigned healthy infants in Kenya to one of seven equal-sized trial groups. Participants in groups A through F were assigned to receive either a fractional or full dose of PCV10 or PCV13, administered as two primary doses plus one booster dose. In group A, participants received a full dose of PCV13; group B, a 40% dose of PCV13; group C, a 20% dose of PCV13; group D, a full dose of PCV10; group E, a 40% dose of PCV10; and group F, a 20% dose of PCV10. Participants in the seventh group (group G) received a full dose of PCV10 as three primary doses without a booster. Immunogenicity was assessed 4 weeks after the primary series of doses and 4 weeks after the booster dose. Noninferiority could be declared 4 weeks after the primary series if the difference in the percentage of participants with a threshold response was not more than 10% and 4 weeks after administration of the booster if the ratio of the geometric mean concentration (GMC) of IgG was more than 0.5. A vaccine dose was prespecified as noninferior if it met the noninferiority criterion for at least 8 of the 10 vaccine types in the PCV10 groups or at least 10 of the 13 vaccine types in the PCV13 groups. Carriage was assessed when participants were 9 months and 18 months of age. RESULTS: In the per-protocol analysis, 40% of a full dose of PCV13 met the noninferiority criterion for 12 of 13 serotypes after the primary series and for 13 of 13 serotypes after the booster. The immunogenicity of the 20% dose of PCV13 and of the 40% and 20% doses of PCV10 was not noninferior to that of the full doses. Vaccine serotype-type carriage prevalence was similar across the PCV13 groups at 9 months and 18 months of age. CONCLUSIONS: In a three-dose schedule (two primary doses and a booster), 40% doses of PCV13 were noninferior to full doses for all included serotypes. Lower doses of PCV13 and PCV10 did not meet the criteria for noninferiority. (Funded by the Bill and Melinda Gates Foundation and others; ClinicalTrials.gov number, NCT03489018; Pan African Clinical Trial Registry number, PACTR202104717648755.).

Seroprevalence of Antibodies to Severe Acute Respiratory Syndrome Coronavirus 2 Among Healthcare Workers in Kenya.

BACKGROUND: Few studies have assessed the seroprevalence of antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among healthcare workers (HCWs) in Africa. We report findings from a survey among HCWs in 3 counties in Kenya. METHODS: We recruited 684 HCWs from Kilifi (rural), Busia (rural), and Nairobi (urban) counties. The serosurvey was conducted between 30 July and 4 December 2020. We tested for immunoglobulin G antibodies to SARS-CoV-2 spike protein, using enzyme-linked immunosorbent assay. Assay sensitivity and specificity were 92.7 (95% CI, 87.9-96.1) and 99.0% (95% CI, 98.1-99.5), respectively. We adjusted prevalence estimates, using bayesian modeling to account for assay performance. RESULTS: The crude overall seroprevalence was 19.7% (135 of 684). After adjustment for assay performance, seroprevalence was 20.8% (95% credible interval, 17.5%-24.4%). Seroprevalence varied significantly (P < .001) by site: 43.8% (95% credible interval, 35.8%-52.2%) in Nairobi, 12.6% (8.8%-17.1%) in Busia and 11.5% (7.2%-17.6%) in Kilifi. In a multivariable model controlling for age, sex, and site, professional cadre was not associated with differences in seroprevalence. CONCLUSION: These initial data demonstrate a high seroprevalence of antibodies to SARS-CoV-2 among HCWs in Kenya. There was significant variation in seroprevalence by region, but not by cadre.

Determining the optimal diagnostic and risk stratification approaches for people with hypertension in two rural populations in Kenya and The Gambia: a study protocol for IHCoR-Africa Work Package 2.

Background: Sub-Saharan Africa (SSA) has one of the highest prevalences of hypertension worldwide. The impact of hypertension is of particular concern in rural SSA, where access to clinics and hospitals is limited. Improvements in the management of people with hypertension in rural SSA could be achieved by sharing diagnosis and care tasks between the clinic and the community. To develop such a community-centred programme we need optimal approaches to identify and risk stratify patients with elevated blood pressure. The aim of the study is to improve the evidence base for diagnosis and risk estimation for a community-centred hypertension programme in two rural settings in SSA. Methods: We will conduct a cross-sectional study of 1250 adult participants in Kilifi, Kenya and Kiang West, The Gambia. The study has five objectives which will determine the: (1) accuracy of three blood pressure (BP) measurement methods performed by community health workers in identifying people with hypertension in rural SSA, compared to the reference standard method; (2) relationship between systolic BP and cardiovascular risk factors; (3) prevalence of hypertension-mediated organ damage (HMOD); (4) accuracy of innovative point-of-care (POC) technologies to identify patients with HMOD; and (5) cost-effectiveness of different combinations of BP and HMOD measurements for directing hypertension treatment initiation. Expected findings: This study will determine the accuracy of three methods for community BP measurement and POC technologies for HMOD assessment. Using the optimal methods in this setting it will estimate the prevalence of hypertension and provide the best estimate to date of HMOD prevalence in SSA populations. The cost-effectiveness of decision-making approaches for initiating treatment of hypertension will be modelled. These results will inform the development of a community-centred programme to improve care for hypertensive patients living in rural SSA. Existing community engagement networks will be used to disseminated within the research setting.

Many people live with high blood pressure in sub-Saharan Africa. In this region, the proportion of people with high blood pressure is one of the highest in the world. However, few people with high blood pressure are treated and this can lead to serious medical issues and even death. This is particularly true in rural areas where treatment and understanding of blood pressure is lower than in cities. There are many reasons why high blood pressure is a major health problem in rural sub-Saharan Africa, such as a lack of clear symptoms; less access to healthcare; and limited time to travel to clinics for care. One option for improving the management of blood pressure is to use a community-centred approach, where care is brought into the community making it easier to access. To bring care into the community, we need to find out what is the best way for community health workers to identify who needs to be treated. Standard techniques may not be useful in a rural community and could require too many resources to make them practical. This study aims to determine what is the best way to identify high blood pressure and related health complications in a community setting. The study will take place across two sites: one in Kilifi, Kenya and the other in Kiang West, The Gambia. We will enrol 1250 participants, with 625 in each country. The people living in these areas have been involved in the design of this study through community engagement and have helped identify the need for improving how blood pressure is treated in a rural areas. Throughout this study, we will continue to meet with the communities. Once the study is completed, we will use our strong links with the communities, healthcare providers and policymakers to share the results.

Sero-surveillance for IgG to SARS-CoV-2 at antenatal care clinics in three Kenyan referral hospitals: Repeated cross-sectional surveys 2020-21.

INTRODUCTION: The high proportion of SARS-CoV-2 infections that have remained undetected presents a challenge to tracking the progress of the pandemic and estimating the extent of population immunity. METHODS: We used residual blood samples from women attending antenatal care services at three hospitals in Kenya between August 2020 and October 2021and a validated IgG ELISA for SARS-Cov-2 spike protein and adjusted the results for assay sensitivity and specificity. We fitted a two-component mixture model as an alternative to the threshold analysis to estimate of the proportion of individuals with past SARS-CoV-2 infection. RESULTS: We estimated seroprevalence in 2,981 women; 706 in Nairobi, 567 in Busia and 1,708 in Kilifi. By October 2021, 13% of participants were vaccinated (at least one dose) in Nairobi, 2% in Busia. Adjusted seroprevalence rose in all sites; from 50% (95%CI 42-58) in August 2020, to 85% (95%CI 78-92) in October 2021 in Nairobi; from 31% (95%CI 25-37) in May 2021 to 71% (95%CI 64-77) in October 2021 in Busia; and from 1% (95% CI 0-3) in September 2020 to 63% (95% CI 56-69) in October 2021 in Kilifi. Mixture modelling, suggests adjusted cross-sectional prevalence estimates are underestimates; seroprevalence in October 2021 could be 74% in Busia and 72% in Kilifi. CONCLUSIONS: There has been substantial, unobserved transmission of SARS-CoV-2 in Nairobi, Busia and Kilifi Counties. Due to the length of time since the beginning of the pandemic, repeated cross-sectional surveys are now difficult to interpret without the use of models to account for antibody waning.