Who is missed in a community-based survey: Assessment and implications of biases due to incomplete sampling frame in a community-based serosurvey, Choma and Ndola Districts, Zambia, 2022

Community-based serological studies are increasingly relied upon to measure disease burden, identify population immunity gaps, and guide control and elimination strategies; however, there is little understanding of the potential for and impact of sampling biases on outcomes of interest. As part of efforts to quantify measles immunity gaps in Zambia, a community-based serological survey using stratified multi-stage cluster sampling approach was conducted in Ndola and Choma districts in May-June 2022, enrolling 1245 individuals. We carried out a follow-up study among individuals missed from the sampling frame of the serosurvey in July-August 2022, enrolling 672 individuals. We assessed the potential for and impact of biases in the community-based serosurvey by i) estimating differences in characteristics of households and individuals included and excluded (77% vs 23% of households) from the sampling frame of the serosurvey and ii) evaluating the magnitude these differences make on healthcare-seeking behavior, vaccination coverage, and measles seroprevalence. We found that missed households were 20% smaller and 25% less likely to have children. Missed individuals resided in less wealthy households, had different distributions of sex and occupation, and were more likely to seek care at health facilities. Despite these differences, simulating a survey in which missed households were included in the sampling frame resulted in less than a 5% estimated bias in these outcomes. Although community-based studies are upheld as the gold standard study design in assessing immunity gaps and underlying community health characteristics, these findings underscore the fact that sampling biases can impact the results of even well-conducted community-based surveys. Results from these studies should be interpreted in the context of the study methodology and challenges faced during implementation, which include shortcomings in establishing accurate and up-to-date sampling frames. Failure to account for these shortcomings may result in biased estimates and detrimental effects on decision-making.

Respiratory viruses in rural Zambia during the second year of the COVID-19 pandemic

Objectives

Limited data on respiratory infections are available from sub-Saharan Africa during the COVID-19 pandemic. The objective of this study was to evaluate the burden of respiratory viruses in rural Zambia from 2019-2021.

Methods

Surveillance was initiated at Macha Hospital in Zambia in December 2018. Each week, patients with respiratory symptoms were enrolled from the outpatient clinic. Nasopharyngeal samples were collected and tested for respiratory pathogens. The prevalence of respiratory symptoms and viruses in 2021 was compared to results from 2019 and 2020.

Results

After seeing few cases of influenza virus and respiratory syncytial virus in 2020, a return to prepandemic levels was observed in 2021. Rhinovirus/enterovirus, parainfluenza virus 1-4, and adenovirus circulated from 2019 to 2021, while human metapneumovirus and human coronaviruses (HKU1, 229E, OC43, and NL63 subtypes) were observed sporadically. SARS-CoV-2 was observed consistently in 2021 after being first identified in December 2020. The proportion of participants with co-infections in 2021 (11.6%) was significantly higher than in 2019 (6.9%) or 2020 (7.7%).

Conclusion

Declines in influenza virus and respiratory syncytial virus were reversed once public health measures were lifted. Respiratory viruses contributed to a significant burden of respiratory infections in 2021. This study provides important information about respiratory viruses in this changing context and underrepresented region.

The Evolving Pediatric HIV Epidemic in Rural Southern Zambia: The Beneficial Impact of Advances in Prevention and Treatment at a District Hospital From 2007 to 2019

BACKGROUND

Remarkable progress has been made in expanding access to services addressing the pediatric HIV epidemic, including programs to prevent mother-to-child transmission, early diagnosis and treatment for children living with HIV. Few long-term data are available from rural sub-Saharan Africa to assess implementation and impact of national guidelines.

METHODS

Results from 3 cross-sectional studies and 1 cohort study conducted at Macha Hospital in Southern Province, Zambia from 2007 to 2019 were summarized. For infant diagnosis, maternal antiretroviral treatment, infant test results and turnaround times for results were evaluated by year. For pediatric HIV care, the number and age of children initiating care and treatment, and treatment outcomes within 12 months were evaluated by year.

RESULTS

Receipt of maternal combination antiretroviral treatment increased from 51.6% in 2010-2012 to 93.4% in 2019, and the proportion of infants testing positive decreased from 12.4% to 4.0%. Turnaround times for results returning to clinic varied but were shorter when labs consistently used a text messaging system. The proportion of mothers receiving results was higher when a text message intervention was piloted. The number of children living with HIV enrolled into care and the proportion initiating treatment with severe immunosuppression and dying within 12 months decreased over time.

CONCLUSIONS

These studies demonstrate the long-term beneficial impact of implementing a strong HIV prevention and treatment program. While expansion and decentralization brought challenges, the program succeeded in decreasing the rate of mother-to-child transmission and ensuring that children living with HIV benefit from access to life-saving treatment.

Acceptability of serosurveys in southern Zambia: data collector and caregiver perspectives

Background

Factors associated with whether individuals choose to participate in serosurveys are not well understood. Understanding perceptions from multiple perspectives, including the perspectives of both data collectors and participants, through a holistic model such as the socio-ecological model contextualizes individual, interpersonal, and structural level influences on survey research participation. We used a multiple methods approach to characterize reasons for serosurvey participation in communities in Southern Province, Zambia where a serosurvey was conducted in 2016.

Methods

The first phase conducted focus group discussions and in-depth interviews with 24 data collectors who participated in a measles-rubella serosurvey in 2016. The second phase surveyed 34 caregivers at health facilities to identify barriers and facilitators to serosurvey participation. Emergent themes were then classified into a socio-ecological model using individual, interpersonal, and structural level constructs.

Results

Common themes emerged from data collectors as well as caregivers surveyed. At the individual level, providing incentives was a facilitator, and some religious beliefs were described as a barrier to serosurvey participation. At the interpersonal level, family dynamics and community peer influences could help or hinder serosurvey participation. Community health workers were consistently named as facilitators of participation. At the structural level, concerns about specimen collection, who was selected for serosurveys, and not receiving test results arose as potential barriers. The most frequently reported facilitator was provision of information about the purpose of the serosurvey (85% of respondents). The most frequently reported barrier was lack of clarity regarding use of their blood specimen (53% of respondents). For specimen collection type, caregivers consistently preferred finger prick blood collection over both venous blood draw and oral swabs.

Conclusion

Serosurvey participation was deemed acceptable to most study participants. The socio-ecological model revealed barriers and facilitators for participation to guide strategies to improve participation which can be applied to ongoing serosurveys for SARS-CoV-2. Serosurveys should continue to develop engagement plans to provide information about blood collection ahead of the serosurvey and communicate the objectives of such studies through trusted sources such as community health workers and traditional leaders.

Factors associated with antiretroviral therapy use among pregnant women in rural and urban settings in Southern Province, Zambia: 2016-2019

OBJECTIVES

To assess antiretroviral therapy (ART) coverage among pregnant women living with HIV and compare the characteristics of women who received and did not receive ART during pregnancy in Zambia.

METHODS

A cross-sectional study was conducted at urban and rural health facilities in Southern Province, Zambia, from 2016 to 2019. Pregnant women living with HIV delivering at study sites were enrolled and administered a questionnaire, and the results of infant diagnostic testing for HIV at birth was documented.

RESULTS

About 1184 mother/infant pairs were enrolled. ART coverage was 93.7%. Most women who did not receive ART during pregnancy reported HIV diagnosis at delivery (18.0%) or during pregnancy (57.7%). The primary reported reason for not receiving ART was not wanting to take the drugs. Women who did not receive ART during pregnancy were significantly younger, less likely to have disclosed their HIV-infection status to others, and less likely to have received antenatal care than women who received ART. ART use correlated with higher levels of education in urban but not rural sites. Overall, 1.0% of infants were infected with HIV at birth, including 0.8% of infants born to women who received ART and 4.1% of infants born to women who did not.

CONCLUSIONS

Most women received ART according to guidelines, resulting in low perinatal transmission rates of HIV to infants. Efforts to increase ART coverage and prevent vertical transmission should focus on identifying incident HIV infections during pregnancy and strengthening counselling for newly diagnosed pregnant women.

Respiratory viruses in rural Zambia before and during the COVID-19 pandemic

OBJECTIVES

With the emergence of the COVID-19 pandemic, restrictions were implemented globally to control the virus. Data on respiratory pathogens in sub-Saharan Africa during the COVID-19 pandemic are scarce. This analysis was conducted to evaluate patterns of respiratory pathogens in rural Zambia before and during the first year of the pandemic.

METHODS

Surveillance was established in December 2018 at Macha Hospital in southern Zambia. Patients with respiratory symptoms in the outpatient and inpatient clinics were recruited. Nasopharyngeal samples were collected and tested for respiratory pathogens. The prevalence of respiratory symptoms and pathogens was evaluated and compared in the first (December 10, 2018-December 9, 2019) and second (December 10, 2019-November 30, 2020) years of surveillance.

RESULTS

Outpatient visits and admissions for respiratory illness significantly decreased from the first to second year, especially among children. SARS-CoV-2 was not detected from any participants in Year 2. Among outpatients and inpatients with respiratory symptoms, the prevalence of respiratory syncytial virus and influenza viruses decreased from the first to second year. In contrast, the prevalence of rhinovirus/enterovirus, metapneumovirus and parainfluenza virus increased.

CONCLUSIONS

The epidemiology of respiratory viruses in rural Zambia changed during the first year of the COVID-19 pandemic, suggesting that public health interventions may have had an impact on the introduction and circulation of respiratory pathogens in this area.

Facility-based surveillance for influenza and respiratory syncytial virus in rural Zambia

BACKGROUND

While southern Africa experiences among the highest mortality rates from respiratory infections, the burden of influenza and respiratory syncytial virus (RSV) in rural areas is poorly understood.

METHODS

We implemented facility-based surveillance in Macha, Zambia. Outpatients and inpatients presenting with influenza-like illness (ILI) underwent testing for influenza A, influenza B, and RSV and were prospectively followed for 3 to 5 weeks to assess clinical course. Log-binomial models assessed correlates of infection and clinical severity.

RESULTS

Between December 2018 and December 2019, 17% of all outpatients presented with ILI and 16% of inpatients were admitted with an acute respiratory complaint. Influenza viruses and RSV were detected in 17% and 11% of outpatient participants with ILI, and 23% and 16% of inpatient participants with ILI, respectively. Influenza (July-September) and RSV (January-April) prevalence peaks were temporally distinct. RSV (relative risk [RR]: 1.78; 95% confidence interval [CI] 1.51-2.11), but not influenza, infection was associated with severe disease among patients with ILI. Underweight patients with ILI were more likely to be infected with influenza A (prevalence ratio [PR]: 1.72; 95% CI 1.04-2.87) and to have severe influenza A infections (RR: 2.49; 95% CI 1.57-3.93).

CONCLUSIONS

Populations in rural Zambia bear a sizeable burden of viral respiratory infections and severe disease. The epidemiology of infections in this rural area differs from that reported from urban areas in Zambia.

Nosocomial Respiratory Infections in a Rural Zambian Hospital

The burden of nosocomial respiratory infections in rural southern Africa is poorly understood. We established a surveillance program at a rural Zambian hospital to detect influenza-like illness (ILI) and respiratory infections among hospitalized patients and a cohort of healthcare workers (HCWs). Nasopharyngeal specimens from symptomatic patients and HCWs underwent broadly multiplexed molecular testing to detect viruses and atypical bacteria. During 1 year of surveillance, 15 patients (1.7% of admissions) developed ILI more than 48 hours after admission. Among 44 HCWs, 19 (43%) experienced at least one ILI episode, with a total of 31 ILI episodes detected. Respiratory viruses were detected in 45% of patient and 55% of HCW specimens. The cumulative incidence of influenza infection among HCWs over 1 year was 9%. Overall, respiratory viruses were commonly found among patients and HCWs in a rural Zambian hospital with limited infection control infrastructure.

Treatment outcomes among children younger than five years living with HIV in rural Zambia, 2008-2018: a cohort study

Background

HIV testing and treatment guidelines for children in sub-Saharan Africa have evolved over time, such that children are now treated at younger ages. The objective of this study was to describe the treatment experience for immunologic, virologic, and growth outcomes among HIV-infected Zambian children younger than 5 years of age from 2008 to 2018.

Methods

Participants enrolled in a clinical cohort study in Macha, Zambia and initiating antiretroviral treatment before 5 years of age between 2008 and 2015 were included in the analysis and followed up to the end of 2018. Outcomes, including growth, CD4+ T-cell percentage, viral suppression, and mortality, were evaluated among all children using longitudinal and survival analyses. Comparisons by age at treatment initiation (< 1, 1 to < 2, and 2 to < 5 years) were also evaluated.

Results

Three hundred eighty-one children initiating treatment before 5 years of age between 2008 and 2015 were included in the analysis. Growth metrics and CD4+ T-cell percentage improved over time after treatment initiation. However, 20% of children remained underweight and 40% of children remained stunted after the first 36 months of treatment. 85% of children had a viral load < 400 copies/mL after 12 months of treatment. However, children < 1 year at treatment initiation were more likely to have a detectable viral load in the first 12 months of treatment and less likely to achieve viral suppression compared to older children. Mortality was highest in the first 12 months of treatment, among underweight children, and among children initiating treatment in 2008–2010 compared to 2011–2015.

Conclusions

Most children initiating antiretroviral treatment from 2008 to 2015 in rural Zambia responded well to treatment. However, many children remained underweight and stunted, and experienced high mortality rates during the first few months of treatment. This supports continued efforts to improve early infant diagnosis, nutritional support, and pediatric drug formulations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02793-y.

COVID-19 vaccine hesitancy in Zambia: a glimpse at the possible challenges ahead for COVID-19 vaccination rollout in sub-Saharan Africa

With unprecedented speed, multiple vaccines against SARS-CoV-2 are available 1 year after the COVID-19 pandemic was first identified. As we push to achieve global control through these new vaccines, old challenges present themselves, including cold-chain storage, the logistics of mass vaccination, and vaccine hesitancy. Understanding how much hesitancy toward COVID-19 vaccines might occur and what factors may be driving these concerns can improve the ability of public health workers and communicators to maximize vaccine uptake. We nested a survey within a measles-rubella mass vaccination campaign in Zambia in November 2020 and asked about sentiments and beliefs toward COVID-19 and COVID-19 vaccines. Among parents bringing their children to receive a measles-rubella vaccine, we found high acceptability of COVID-19 vaccination of their children, but substantial uncertainty and hesitancy about receiving the vaccine themselves. COVID-19 vaccination hesitancy was correlated with beliefs around COVID-19 severity and risk, as well as vaccine safety and effectiveness.

The NSEBA Demonstration Project: implementation of a point-of-care platform for early infant diagnosis of HIV in rural Zambia

OBJECTIVES

To describe the experience and resource requirements of implementing point-of-care testing for early infant diagnosis of HIV in rural Zambia.

METHODS

A demonstration project was conducted using a hub-and-spoke model in 2018-2019 at five clinics in rural Zambia. Two testing hubs were established, and all HIV-exposed infants were tested with the GeneXpert system. Data on costs, turnaround times and test results were collected.

RESULTS

Seven hundred and eighty six tests were conducted. At the hubs, results were available a median of 2.4 (IQR: 2.1, 2.8) hours after sample collection and most mothers (84%) received same-day results. At the spoke facilities, results were available a median of 9 days (IQR: 7, 12) after sample collection and provided to the mother a median of 16 days (IQR: 10, 28) after sample collection. Eleven children tested positive, and 9 (82%) started treatment a median of 13 days (IQR: 7, 21) after sample collection and on the day mothers received results. In contrast, results from matching samples sent for routine testing were available a median of 38 days (IQR: 27, 61) after sample collection and provided to the mother a median of 91 days (IQR: 47, 135) after sample collection.

CONCLUSIONS

Implementing point-of-care testing in a network of rural health centres in Zambia required significant initial and ongoing investment in infrastructure, training and supervision. However, point-of-care testing can rapidly diagnose HIV-infected infants, so they can benefit from early treatment.

Acceptability and feasibility of testing for HIV infection at birth and linkage to care in rural and urban Zambia: a cross-sectional study

BACKGROUND

Early infant diagnosis is important for timely identification of HIV-infected infants and linkage to care. Testing at birth has been implemented to facilitate earlier diagnosis of HIV infection but may present new challenges. This study was conducted to understand the acceptability and feasibility of birth testing in urban and rural settings in southern Zambia.

METHODS

This cross-sectional study was conducted at 11 hospitals and clinics in Livingstone, Choma, and Macha in Southern Province, Zambia from 2016 to 2018. Infants born to pregnant women living with HIV at the sites were eligible for enrollment. After enrollment, a questionnaire was administered to the mother and a dried blood spot card was collected from infants for testing at a central laboratory. When results were available, mothers were notified to return to the clinic. Acceptability of birth testing was evaluated based on the proportion of women who agreed to participate and the reasons for non-participation among women who declined. Feasibility of testing at birth was evaluated using turnaround times for returning results, the proportion of women receiving results, and linkage to care for infants testing positive.

RESULTS

One thousand four hundred three women were approached for the study. A small proportion declined due to refusal of birth testing (0 to 8.2% across sites). One thousand two hundred ninety women agreed to have their infants tested. The proportion of mothers receiving results ranged from 51.6 to 92.1%, and was significantly lower at the hospital than clinics in Livingstone (51.6% vs. 69.8%; p < 0.0001) and Macha (69.5% vs. 85.7%; p < 0.0001) but not Choma (85.7% vs. 92.1%; p = 0.34). For mothers who received test results, the median turnaround time from sample collection was 67 days in Livingstone and 53 days in Macha and Choma. Overall, 23 (1.8%) infants tested positive for HIV but only 8 (34.8%) were linked to care a median of 68 days (range: 29, 784) after sample collection.

CONCLUSIONS

While testing at birth was acceptable, this study highlights the operational challenges under a centralized laboratory testing system. Point-of-care platforms are needed for rapid testing and return of results so HIV-infected children can be identified, linked to care, and treated as early as possible.

Use of mobile phones and text messaging to decrease the turnaround time for early infant HIV diagnosis and notification in rural Zambia: an observational study

BACKGROUND

Early infant diagnosis of HIV infection is challenging in rural sub-Saharan Africa as blood samples are sent to central laboratories for HIV DNA testing, leading to delays in diagnosis and treatment initiation. Simple technologies to rapidly deliver results to clinics and notify mothers of test results would decrease many of these delays. The feasibility of using mobile phones to contact mothers was evaluated. In addition, the first two years of implementation of a national short message service (SMS) reporting system to deliver test results from the laboratory to the clinic were evaluated.

METHODS

The study was conducted in Macha, Zambia from 2013 to 2015 among mothers of HIV-exposed infants. Mothers were interviewed about mobile phone use and willingness to be contacted directly or through their rural health center. Mothers were contacted according to their preferred method of communication when test results were available. Mothers of positive infants were asked to return to the clinic as soon as possible. Dates of sample collection, delivery of test results to the clinic and notification of mothers were documented in addition to test results.

RESULTS

Four hundred nineteen mothers and infants were enrolled. Only 30% of mothers had ever used a mobile phone. 96% of mobile phone owners were reached by study staff and 98% of mothers without mobile phones were contacted through their rural health center. Turnaround times for mothers of positive infants were approximately 2 weeks shorter than for mothers of negative infants. Delivery of test results by the national SMS system improved from 2013 to 2014, with increases in the availability of texted results (38 vs. 91%) and arrival of the texted result prior to the hardcopy report (27 vs. 83%). Texted results arriving at the clinic before the hardcopy were received a median of 19 days earlier. Four discrepancies between texted and hardcopy results were identified out of 340 tests.

CONCLUSIONS

Mobile phone and text messaging technology has the potential to improve early infant diagnosis but challenges to widespread implementation need to be addressed, including low mobile phone ownership, use and coverage in rural areas.