RESUMO
The uptake of wastewater-based epidemiology (WBE) for SARS-CoV-2 as a complementary tool for monitoring population-level epidemiological features of the COVID-19 pandemic in low-and-middle-income countries (LMICs) is low. We report on the findings from the South African SARS-CoV-2 WBE surveillance network and make recommendations regarding the implementation of WBE in LMICs. Eight laboratories quantified influent wastewater collected from 87 wastewater treatment plants in all nine South African provinces from 01 June 2021 to 31 May 2022 inclusive, during the 3rd and 4th waves of COVID-19. Correlation and regression analyses between wastewater levels of SARS-CoV-2 and district laboratory-confirmed caseloads were conducted. The sensitivity and specificity of novel 'rules' based on WBE data to predict an epidemic wave were determined. Amongst 2158 wastewater samples, 543/648 (85 %) samples taken during a wave tested positive for SARS-CoV-2 compared with 842 positive tests from 1512 (55 %) samples taken during the interwave period. Overall, the regression-co-efficient was 0,66 (95 % confidence interval = 0,6-0,72, R2 = 0.59), ranging from 0.14 to 0.87 by testing laboratory. Early warning of the 4th wave of SARS-CoV-2 in Gauteng Province in November-December 2021 was demonstrated. A 50 % increase in log copies of SARS-CoV-2 compared with a rolling mean over the previous five weeks was the most sensitive predictive rule (58 %) to predict a new wave. Our findings support investment in WBE for SARS-CoV-2 surveillance in LMICs as an early warning tool. Standardising test methodology is necessary due to varying correlation strengths across laboratories and redundancy across testing plants. A sentinel site model can be used for surveillance networks without affecting WBE finding for decision-making. Further research is needed to identify optimal test frequency and the need for normalisation to population size to identify predictive and interpretive rules to support early warning and public health action.
Assuntos
COVID-19 , Negro ou Afro-Americano , População Negra , Humanos , SARS-CoV-2 , Organização Mundial da SaúdeRESUMO
This paper describes how an up-to-date national population register recording deaths by age and sex, whether deaths were due to natural or unnatural causes, and the offices at which the deaths were recorded can be used to monitor excess death during the SARS-CoV-2 pandemic, both nationally, and sub-nationally, in a country with a vital registration system that is neither up to date nor complete. Apart from suggesting an approach for estimating completeness of reporting at a sub-national level, the application produces estimates of the number of deaths in excess of those expected in the absence of the SARS-CoV-2 epidemic that are highly correlated with the confirmed number of COVID-19 deaths over time, but at a level 2.5 to 3 times higher than the official numbers of COVID-19 deaths. Apportioning the observed excess deaths more precisely to COVID, COVID-related and collateral deaths, and non-COVID deaths averted by interventions with reduced mobility and gatherings, etc., requires access to real-time cause-of-death information. It is suggested that the transition from ICD-10 to ICD-11 should be used as an opportunity to change from a paper-based system to electronic capture of the medical cause-of-death information.
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This study applies survival analysis to the birth histories from 317 national surveys to model pathways to low fertility in 83 less-developed countries between 1965 and 2014. It presents period measures of parity progression, the length of birth intervals and total fertility that have been standardized fully for age, parity, and interval duration. It also examines parity-specific trends in the proportion of women who want no more children. Outside sub-Saharan Africa, fertility transition was dominated by parity-specific family size limitation. As the transition progressed, women also began to postpone their next birth for lengthy periods in many countries. During the first half of the fertility transition in much of sub-Saharan Africa and in some other countries, however, women stopped childbearing without targeting particular family sizes. Moreover, birth intervals in sub-Saharan Africa have been lengthening since the onset of the transition. Birth control is not restricted to a dichotomy between limitation and spacing. Other reasons for curtailing childbearing and postponing having another birth also shape countries' pathways through fertility transition.
Assuntos
Intervalo entre Nascimentos/estatística & dados numéricos , Coeficiente de Natalidade/tendências , Países em Desenvolvimento/estatística & dados numéricos , Características da Família , África Subsaariana/epidemiologia , Fatores Etários , Feminino , Humanos , Paridade , Fatores SocioeconômicosRESUMO
The relationship between teenage childbearing and school attainment is investigated using nationally representative longitudinal data drawn from South Africa's National Income Dynamics Study. The analysis focuses on the outcomes by 2010 of a panel of 673 young women who were aged 15-18 and childless in 2008. Controlling for other factors, girls who went on to give birth had twice the odds of dropping out of school by 2010 and nearly five times the odds of failing to matriculate. Few girls from households in the highest-income quintile gave birth. Girls who attended schools in higher-income areas and were behind at school were much more likely to give birth than those who were in the appropriate grade for their age or were in no-fee schools. New mothers were much more likely to have re-enrolled in school by 2010 if they were rural residents, they belonged to relatively well-off households, or their own mother had attended secondary school. These findings suggest that, in South Africa, interventions that address poor school attainment would also reduce teenage childbearing.
Assuntos
Características da Família , Gravidez na Adolescência/estatística & dados numéricos , Comportamento Reprodutivo/estatística & dados numéricos , Evasão Escolar/estatística & dados numéricos , Adolescente , Adulto , Escolaridade , Feminino , Humanos , Renda/estatística & dados numéricos , Estudos Longitudinais , Gravidez , África do Sul , Adulto JovemRESUMO
This paper investigates the impact on birth intervals of three distinct birth control strategies: stopping childbearing, spacing births and the postponement of further childbearing for reasons unrelated to women's family-building histories. A macro-simulation model of the family-building process is described that incorporates heterogeneity in fecundability. This model is used to demonstrate that the postponement of further childbearing has a distinctive impact on schedules of duration-specific fertility rates that differs from that of both family-size limitation and birth spacing. In particular, the simulation results, supplemented by an analytical exposition, show that reductions in fertility due to spacing are a function of interval duration and its log, while reductions due to postponement are a function of interval duration and its square. This provides a way to test statistically for the presence of, and distinguish between, differential postponement and spacing in regression analyses of birth history data.
Assuntos
Intervalo entre Nascimentos/estatística & dados numéricos , Anticoncepção/estatística & dados numéricos , Fertilidade , Fatores Etários , Características da Família , Feminino , Humanos , Modelos Estatísticos , Paridade , GravidezRESUMO
We investigated birth-interval dynamics in 24 African countries using data from 76 Demographic and Health Surveys conducted since 1986. Controlling for selection bias in the birth-history data using the Brass-Juárez method and regression models produced almost identical results. Birth intervals have lengthened in every country examined. This analysis uncovered a distinctive and previously undocumented pattern of childbearing that is prevalent across sub-Saharan Africa. After allowing for time trends in birth-interval length, the lengthening of birth intervals in almost every country varies little by women's age or parity. Moreover, in several countries, birth intervals are now too long to be explicable by birth spacing contingent on the age of women's youngest child. Rather, women are postponing births for other reasons. These findings offer empirical support for the idea that the fertility transition in sub-Saharan Africa is following a different pattern from that observed elsewhere.
Assuntos
Intervalo entre Nascimentos/estatística & dados numéricos , Coeficiente de Natalidade/etnologia , Serviços de Planejamento Familiar/estatística & dados numéricos , Comportamento Reprodutivo/estatística & dados numéricos , Adulto , África , África Subsaariana , Coeficiente de Natalidade/tendências , Feminino , Inquéritos Epidemiológicos , Humanos , Pessoa de Meia-Idade , Gravidez , Prevalência , Análise de Regressão , Comportamento Reprodutivo/etnologia , Fatores de TempoRESUMO
This paper examines the risk of child mortality associated with short preceding birth intervals in Mozambique. We apply a piecewise log-rate model to a pooled dataset comprising 36,305 live births from the 1997 and 2003 Mozambique Demographic and Health Surveys (DHS). Our results show that the effects of short preceding intervals are strongest during the first month of life, particularly the first week, indicating prenatal maternal depletion as the dominant pathway. The rapid decline in mortality rates from intervals of less than six months to the category 30 to 35 months suggests an optimal waiting period of at least 30 months between one birth and the next pregnancy. 73 per cent of births had preceding intervals less than 30 months which, amidst low contraception use, indicates a potential for family planning programs to contribute to child survival and the attainment of Millennium Development Goal 4 in Mozambique.
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Intervalo entre Nascimentos/estatística & dados numéricos , Mortalidade da Criança , Serviços de Planejamento Familiar/organização & administração , Mortalidade Infantil , Saúde Reprodutiva/estatística & dados numéricos , Adolescente , Adulto , Criança , Anticoncepção/estatística & dados numéricos , Interpretação Estatística de Dados , Feminino , Inquéritos Epidemiológicos/estatística & dados numéricos , Humanos , Lactente , Recém-Nascido , Idade Materna , Pessoa de Meia-Idade , Moçambique/epidemiologia , Paridade , Gravidez , Saúde Reprodutiva/educação , Fatores de Risco , Fatores Socioeconômicos , Taxa de SobrevidaRESUMO
This paper describes marriage and partnership patterns and trends in rural KwaZulu-Natal, South Africa from 2000-2006. The study is based on longitudinal, population-based data collected by the Africa Centre demographic surveillance system. We consider whether the high rates of non-marriage among Africans in South Africa reported in the 1980s were reversed following the political transformation underway by the 1990s. Our findings show that marriage has continued to decline with a small increase in cohabitation among unmarried couples, particularly in more urbanised areas. Comparing surveillance and census data, we highlight problems with the use of the 'living together' marital status category in a highly mobile population.
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An article recently published in this journal argues that the life expectancies (and other mortality statistics) produced by models of the HIV/AIDS epidemic in Southern Africa are inconsistent, and questions their reliability. To demonstrate the argument, the author of that paper derived empirical estimates of several mortality statistics from three different sources of data and, on the grounds that the estimates of life expectancy for 2001 and 2006 are somewhat higher than is typically estimated by projection models, concludes that the empirical evidence supports the theoretical view outlined in that paper. If correct, the reasoning (and its empirical demonstration) could be construed as a strong challenge to a dominant orthodoxy surrounding the estimation of mortality statistics in an era of HIV/AIDS and offering some comfort to governments with low Human Development Indices because of the index's dependence, inter alia, on estimates of life expectancy at birth derived from such models. This paper shows how, on theoretical, methodological and empirical grounds, the reasoning and estimates in the paper are severely flawed, and thus that the conclusions drawn in that paper are unjustified.
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Infecções por HIV/epidemiologia , Infecções por HIV/mortalidade , Expectativa de Vida , Modelos Biológicos , Adolescente , Adulto , Criança , Mortalidade da Criança , Pré-Escolar , Interpretação Estatística de Dados , Feminino , Humanos , Lactente , Mortalidade Infantil , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Prevalência , África do Sul/epidemiologiaRESUMO
Stalled fertility declines have been identified in several regions across the developing world, but the current conceptualization of a stalled fertility decline is poorly theorized and does not lend itself to objective measurement. We propose a more rigorous and statistically testable definition of stalled fertility decline that can be applied to time-series data. We then illustrate the utility of our definition through its application to data from rural South Africa for the period 1990-2005 collected from a demographic surveillance site. Application of the approach suggests that fertility decline has indeed stalled in rural KwaZulu-Natal, at about three children per woman. The stall, some 20 percent above the replacement fertility level, does not appear to be associated with a rise in wanted fertility or attenuated access to contraceptive methods. This identification of a stalled fertility decline provides the first evidence of such a stall in southern Africa, the region with the lowest fertility levels in sub-Saharan Africa.
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Coeficiente de Natalidade/tendências , Fertilidade , População Rural , Adolescente , Adulto , Demografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Vigilância da População , Gravidez , África do Sul/epidemiologiaRESUMO
Little is known about the dynamics of fertility transition in South Africa, though recent studies have begun to shed light on demographic changes in the country. This study presents trends and patterns of fertility observed in a rural South African population. Various demographic and statistical techniques were used to examine fertility patterns in a population of 21,847 women in a rural KwaZulu-Natal (KZN) demographic surveillance area. These are compared with patterns seen in another South African rural population under demographic surveillance, and with data from the 1998 South Africa Demographic and Health Survey. Findings are interpreted in light of contraceptive use patterns and HIV prevalence in the population. In South Africa, the end of the fertility transition is now in sight. In rural KZN, where national fertility levels are highest, fertility has declined rapidly for about two decades and would have reached below replacement level in 2003. While fertility has declined rapidly among all women over age 18 years, fertility levels among adolescents have not changed in decades. Although most adolescents in rural KZN were sexually active (60%), few had ever used contraception (200%). High HIV seroprevalence appears to explain a small part of the fertility decline (12%); however, this effect is likely to grow in the near future as the HIV/AIDS epidemic continues in South Africa. If the current trends continue in the future, below replacement fertility, together with high mortality due to AIDS, it could soon lead to negative natural population growth in rural South Africa.
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Fertilidade , Infecções por HIV/epidemiologia , Saúde da População Rural/tendências , Adolescente , Adulto , Distribuição por Idade , Coeficiente de Natalidade/tendências , Causas de Morte , Comportamento Contraceptivo/estatística & dados numéricos , Feminino , Previsões , Soroprevalência de HIV/tendências , Humanos , Masculino , Pessoa de Meia-Idade , Crescimento Demográfico , Vigilância da População , Sistema de Registros , Estudos Retrospectivos , Distribuição por Sexo , Comportamento Sexual/estatística & dados numéricos , África do Sul/epidemiologiaRESUMO
Inadequate data and apartheid policies have meant that, until recently, most demographers have not had the opportunity to investigate the level of, and trend in, the fertility of South African women. The 1996 South Africa Census and the 1998 Demographic and Health Survey provide the first widely available and nationally representative demographic data on South Africa since 1970. Using these data, this paper describes the South African fertility decline from 1955 to 1996. Having identified and adjusted for several errors in the 1996 Census data, the paper argues that total fertility at that time was 3.2 children per woman nationally, and 3.5 children per woman for African South Africans. These levels are lower than in any other sub-Saharan African country. We show also that fertility in South Africa has been falling since the 1960s. Thus, fertility transition predates the establishment of a family planning programme in the country in 1974.