Mortality in rural coastal Kenya measured using the Kilifi Health and Demographic Surveillance System: a 16-year descriptive analysis

Background: The Kilifi Health and Demographic Surveillance System (KHDSS) was established in 2000 to define the incidence and prevalence of local diseases and evaluate the impact of community-based interventions. KHDSS morbidity data have been reported comprehensively but mortality has not been described. This analysis describes mortality in the KHDSS over 16 years. Methods: We calculated mortality rates from 2003-2018 in four intervals of equal duration and assessed differences in mortality across these intervals by age and sex. We calculated the period survival function and median survival using the Kaplan-Meier method and mean life expectancies using abridged life tables. We estimated trend and seasonality by decomposing a time series of monthly mortality rates. We used choropleth maps and random-effects Poisson regression to investigate geographical heterogeneity. Results: Mortality declined by 36% overall between 2003-2018 and by 59% in children aged <5 years. Most of the decline occurred between 2003 and 2006. Among adults, the greatest decline (49%) was observed in those aged 15-54 years. Life expectancy at birth increased by 12 years. Females outlived males by 6 years. Seasonality was only evident in the 1-4 year age group in the first four years. Geographical variation in mortality was ±10% of the median value and did not change over time. Conclusions: Between 2003 and 2018, mortality among children and young adults has improved substantially. The steep decline in 2003-2006 followed by a much slower reduction thereafter suggests improvements in health and wellbeing have plateaued in the last 12 years. However, there is substantial inequality in mortality experience by geographical location.

394. Impact of Misdiagnosis of Clostridioides difficile Infection (CDI) by Standard-of-care Specimen Collection and Testing on Estimates of Hospitalized CDI Incidence Among Adults in Louisville, Kentucky, 2019-2020

Background

Public health surveillance indicates that there is a high population-based incidence of laboratory-confirmed hospitalized CDI cases in the United States. Although reported CDI cases are identified via standard-of-care (SOC) specimen collection and CDI testing practices, the impact of SOC misdiagnosis on the reported CDI incidence is uncertain.

Methods

Active surveillance from Oct 14, 2019, to Apr 11, 2020, identified inpatients aged ≥50 years with diarrhea (≥3 stools with Bristol score ≥5 in 24 hours) at all wards at 8 of the 9 adult hospitals in Louisville, Kentucky (population >50 years = 276 456). Study stool specimens from inpatients with diarrhea were screened by rapid GDH/toxin membrane enzyme immunoassay and the positive samples tested by PCR and cell cytotoxicity neutralization assay (CCNA). A study CDI case was a patient with PCR positive/CCNA positive stool or PCR positive stool with pseudomembranous colitis (PMC). Incidence (non-recurrent CDI cases/100 000 persons aged >50 years per year [PY]) was adjusted for the hospitalization share of participating hospitals and, in a sensitivity analysis, for patients with diarrhea without a CDI test result. SOC stool specimen CDI testing occurred independent of the study.

Results

Among 1541 inpatients with diarrhea, study testing identified 109 non-recurrent CDI cases; 18 (16.5%) had PMC, 36 (33.0%) were admitted to intensive care, and 21 (19.3%) died during the 90-day follow-up. Study hospitalized CDI incidence was 154/100 000 PY (202/100 000 PY in the sensitivity analysis). SOC hospitalized CDI incidence was 121/100 000 PY. Of the 109 study CDI cases, 44 (40%) were not SOC-diagnosed (SOC under-diagnosis). Of the 75 SOC CDI cases that also had study testing, 12 (16%) were not study CDI cases (SOC over-diagnosis). SOC-undiagnosed and SOC-diagnosed CDI cases had similar demographics, medical histories, and clinical outcomes. Study testing identified 24% more CDI cases than SOC testing.

Conclusion

There was a high incidence of hospitalized CDI in persons aged >50 years (154-202/100,000 PY). Of the hospitalized CDI cases, one-third were admitted to ICU and one-fifth died. Public health surveillance estimates of the incidence of laboratory-confirmed hospitalized CDI cases, which are based on SOC testing, may be under-estimated by 24%.

Disclosures

Frederick Angulo, DVM PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Joann M. Zamparo, MPH, Pfizer: Employee|Pfizer: Stocks/Bonds Elisa Gonzalez, MPH, Pfizer: Employee|Pfizer: Stocks/Bonds Pingping Zhang, MS, Pfizer: Employee|Pfizer: Stocks/Bonds Michael W. Pride, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Sharon Gray, MPH, Pfizer: Employee|Pfizer: Stocks/Bonds Catia Matos Ferreira, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Forest W. Arnold, DO, MSc, Gilead Sciences, Inc.: Grant/Research Support Raul E. Isturiz, MD, Pfizer: Employee|Pfizer: Stocks/Bonds Nadia Minarovic, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Jennifer Moisi, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds Luis Jodar, PhD, Pfizer: Employee|Pfizer: Stocks/Bonds.

Mortality in rural coastal Kenya measured using the Kilifi Health and Demographic Surveillance System: a 16-year descriptive analysis

Background: The Kilifi Health and Demographic Surveillance System (KHDSS) was established in 2000 to define the incidence and prevalence of local diseases and evaluate the impact of community-based interventions. KHDSS morbidity data have been reported comprehensively but mortality has not been described. This analysis describes mortality in the KHDSS over 16 years. Methods: We calculated mortality rates from 2003–2018 in four intervals of equal duration and assessed differences in mortality across these intervals by age and sex. We calculated the period survival function and median survival using the Kaplan–Meier method and mean life expectancies using abridged life tables. We estimated trend and seasonality by decomposing a time series of monthly mortality rates. We used choropleth maps and random-effects Poisson regression to investigate geographical heterogeneity. Results: Mortality declined by 36% overall between 2003–2018 and by 59% in children aged <5 years. Most of the decline occurred between 2003 and 2006. Among adults, the greatest decline (49%) was observed in those aged 15–54 years. Life expectancy at birth increased by 12 years. Females outlived males by 6 years. Seasonality was only evident in the 1–4 year age group in the first four years. Geographical variation in mortality was ±10% of the median value and did not change over time. Conclusions: Between 2003 and 2018, mortality among children and young adults has improved substantially. The steep decline in 2003–2006 followed by a much slower reduction thereafter suggests improvements in health and wellbeing have plateaued in the last 12 years. However, there is substantial inequality in mortality experience by geographical location.

Assessment of health benefits and cost-effectiveness of 10-valent and 13-valent pneumococcal conjugate vaccination in Kenyan children

BACKGROUND

The GAVI Alliance supported 10-valent pneumococcal conjugate vaccine (PCV10) introduction in Kenya. We estimated the cost-effectiveness of introducing either PCV10 or the 13-valent vaccine (PCV13) from a societal perspective and explored the incremental impact of including indirect vaccine effects.

METHODS

The costs and effects of pneumococcal vaccination among infants born in Kenya in 2010 were assessed using a decision analytic model comparing PCV10 or PCV13, in turn, with no vaccination. Direct vaccine effects were estimated as a reduction in the incidence of pneumococcal meningitis, sepsis, bacteraemic pneumonia and non-bacteraemic pneumonia. Pneumococcal disease incidence was extrapolated from a population-based hospital surveillance system in Kilifi and adjustments were made for variable access to care across Kenya. We used vaccine efficacy estimates from a trial in The Gambia and accounted for serotype distribution in Kilifi. We estimated indirect vaccine protection and serotype replacement by extrapolating from the USA. Multivariable sensitivity analysis was conducted using Monte Carlo simulation. We assumed a vaccine price of US$ 3.50 per dose.

FINDINGS

The annual cost of delivering PCV10 was approximately US$14 million. We projected a 42.7% reduction in pneumococcal disease episodes leading to a US$1.97 million reduction in treatment costs and a 6.1% reduction in childhood mortality annually. In the base case analysis, costs per discounted DALY and per death averted by PCV10, amounted to US$ 59 (95% CI 26-103) and US$ 1,958 (95% CI 866-3,425), respectively. PCV13 introduction improved the cost-effectiveness ratios by approximately 20% and inclusion of indirect effects improved cost-effectiveness ratios by 43-56%. The break-even prices for introduction of PCV10 and PCV13 are US$ 0.41 and 0.51, respectively.

CONCLUSIONS

Introducing either PCV10 or PCV13 in Kenya is highly cost-effective from a societal perspective. Indirect effects, if they occur, would significantly improve the cost-effectiveness.

Priorities for research on meningococcal disease and the impact of serogroup A vaccination in the African meningitis belt

For over 100 years, large epidemics of meningococcal meningitis have occurred every few years in areas of the African Sahel and sub-Sahel known as the African meningitis belt. Until recently, the main approach to the control of these epidemics has been reactive vaccination with a polysaccharide vaccine after an outbreak has reached a defined threshold and provision of easy access to effective treatment but this approach has not prevented the occurrence of new epidemics. Meningococcal conjugate vaccines, which can prevent meningococcal carriage and thus interrupt transmission, may be more effective than polysaccharide vaccines at preventing epidemics. Because the majority of African epidemics have been caused by serogroup A meningococci, a serogroup A polysaccharide/tetanus toxoid protein conjugate vaccine (PsA-TT) has recently been developed. Results from an initial evaluation of the impact of this vaccine on meningococcal disease and meningococcal carriage in Burkina Faso have been encouraging. To review how the research agenda for meningococcal disease in Africa has been changed by the advent of PsA-TT and to define a new set of research priorities for study of meningococcal infection in Africa, a meeting of 41 scientists was held in Dakar, Senegal on April 24th and 25th 2012. The research recommendations developed during the course of this meeting are presented in this paper. The need for enhanced surveillance for meningitis in defined populations with good diagnostic facilities in African countries at risk of epidemics was identified as the highest priority. This is needed to determine the duration of protection against serogroup A meningococcal disease provided by PsA-TT and to determine the risk of disease and carriage caused by meningococci of other serogroups. Other research areas given high priority included identification and validation of serological correlates of protection against meningococcal disease and carriage, development of improved methods for detecting carriage and epidemiological studies aimed at determining the reasons underlying the peculiar epidemiology of meningococcal disease in the African meningitis belt. Minutes and working papers from the meeting are provided in supplementary tables and some of the presentations made at the meeting are available on the MenAfriCar consortium website (www.menafricar.org) and on the web site of the Centers for Disease Control (www.cdc.gov).

Predictors of pneumococcal conjugate vaccine immunogenicity among infants and toddlers in an American Indian PnCRM7 efficacy trial

BACKGROUND

Pneumococcal conjugate vaccines are important for the prevention of serious illness and death among infants. Factors associated with pneumococcal conjugate vaccine immunogenicity have not been explored.

METHODS

Children <24 months of age received 2, 3, or 4 doses of 7-valent pneumococcal conjugate vaccine (PnCRM7) or control vaccine depending on age at enrollment. Serum samples were tested for serotype-specific antibodies by enzyme-linked immunosorbant assay. Multiple linear regression was used to determine predictors of immunogenicity.

RESULTS

Among 315 PnCRM7-vaccinated subjects and 295 control subjects enrolled at <7 months of age, geometric mean concentrations (GMCs) of antibodies were significantly higher after dose 3 than after dose 2 for all serotypes except type 4. The proportion of subjects with antibody concentrations > or =5.0 micro g/mL was higher for all serotypes, but the proportion with concentrations > or =0.35 micro g/mL was higher only for types 6B and 23F. Three-dose and 2-dose regimens for those 7-11 and 12-23 months of age, respectively, were highly immunogenic. Increased maternal antibody concentrations were associated with reduced responses to dose 1 and 3 but not to dose 4 of PnCRM7.

CONCLUSIONS

Maternal antibody is associated with a reduced infant response to PnCRM7 but does not interfere with immune memory. In infants, a third priming dose increases the antibody GMC and the proportion achieving an antibody concentration > or =5.0 micro g/mL but has little impact on the proportion achieving a concentration > or =0.35 micro g/mL.