Evaluating the impact of COVID-19 on routine childhood immunizations coverage in Zambia.

There are growing concerns about the comeback of vaccine-preventable diseases. Epidemics exert shocks which affect other health performance indicators such as routine immunizations. Early model forecasts indicate decreased use of immunization services, which puts children at greater risk. Concerns about an increase in morbidity and mortality for illnesses other than COVID-19, particularly in children missing routine vaccinations, are of public health interest. In this study, we evaluate COVID-19 effects on the uptake of routine immunization in Zambia.This was an interrupted time series study. National data on routine immunization coverage between January 2017 and December 2022 were analyzed. Interrupted time series analysis was performed to quantify changes in immunization utilization. To determine if changes in the underlying patterns of utilization of immunization service were correlated with the commencement of COVID-19, seasonally adjusted segmented Poisson regression model was utilised.Utilization of health services was similar with historical levels prior to the first case of COVID-19. There was a significant drop in immunization coverage for measles dose two (RR, 0.59; 95% CI: 0.43-0.80). A decreased slope was observed in immunization coverage of Rotavirus dose one (RR, 0.97; 95% CI: 0.96-0.98) and Rotavirus dose two (RR, 0.97; 95% CI: 0.96-0.98). A growing slope was observed for Oral Poliovirus two (RR, 1.007; 95% CI: 1.004-1.011) and Oral Poliovirus three (RR, 1.007; 95% CI: 1.002-1011). We also observed a growing slope in BCG Bacille Calmette-Guerin (BCG) (RR, 1.001; 95% CI: 1.000-1011) and Pentavalent one (RR, 1.00; 95% CI: 1.001-1008) and three (RR, 1.004; 95% CI: 1.001-1008).The COVID-19 pandemic has had a number of unintended consequences that have affected the use of immunization services. Ensuring continuity in the provision of health services, especially childhood immunization, during pandemics or epidemics is crucial. Therefore, Investing in robust healthcare infrastructure to withstand surges, training and retaining a skilled workforce capable of handling emergencies and routine services simultaneously is very cardinal to avoid vaccine-preventable diseases, causing long-term health effects especially child mortality.

Euvichol-plus vaccine campaign coverage during the 2017/2018 cholera outbreak in Lusaka district, Zambia: a cross-sectional descriptive study.

OBJECTIVE: To determine the coverage for the oral cholera vaccine (OCV) campaign conducted during the 2017/2018 cholera outbreak in Lusaka, Zambia. STUDY DESIGN: A descriptive cross-sectional study employing survey method conducted among 1691 respondents from 369 households following the second round of the 2018 OCV campaign. STUDY SETTING: Four primary healthcare facilities and their catchment areas in Lusaka city (Kanyama, Chawama, Chipata and Matero subdistricts). PARTICIPANTS: A total of 1691 respondents 12 months and older sampled from 369 households where the campaign was conducted. A satellite map-based sampling technique was used to randomly select households. DATA MANAGEMENT AND ANALYSIS: A pretested electronic questionnaire uploaded on an electronic tablet (ODK V.1.12.2) was used for data collection. Descriptive statistics were computed to summarise respondents' characteristics and OCV coverage per dose. Bivariate analysis (χ2 test) was conducted to stratify OCV coverage according to age and sex for each round (p<0.05). RESULTS: The overall coverage for the first, second and two doses were 81.3% (95% CI 79.24% to 83.36%), 72.1% (95% CI 69.58% to 74.62%) and 66% (95% CI 63.22% to 68.78%), respectively. The drop-out rate was 18.8% (95% CI 14.51% to 23.09%). Of the 81.3% who received the first dose, 58.8% were female. Among those who received the second dose, the majority (61.0%) were females aged between 5 and 14 years (42.6%) and 15 and 35 years (27.7%). Only 15.5% of the participants aged between 36 and 65 and 2.5% among those aged above 65 years received the second dose. CONCLUSION: These findings confirm the 2018 OCV campaign coverage and highlight the need for follow-up surveys to validate administrative coverage estimates using population-based methods. Reliance on health facility data alone may mask low coverage and prevent measures to improve programming. Future public health interventions should consider sociodemographic factors in order to achieve optimal vaccine coverage.

Spatial factors for COVID-19 associated community deaths in an urban area of Lusaka, Zambia: an observational study.

We retrospectively analyzed spatial factors for coronavirus disease 2019 (COVID-19)-associated community deaths i.e., brought-in-dead (BID) in Lusaka, Zambia, between March and July 2020. A total of 127 cases of BID with geocoordinate data of their houses were identified during the study period. Median interquartile range (IQR) of the age of these cases was 49 (34-70) years old, and 47 cases (37.0%) were elderly individuals over 60 years old. Seventy-five cases (75%) of BID were identified in July 2020, when the total number of cases and deaths was largest in Zambia. Among those whose information regarding their underlying medical condition was available, hypertension was most common (22.9%, 8/35). Among Lusaka's 94 townships, the numbers (median, IQR) of cases were significantly larger in those characterized as unplanned residential areas compared to planned areas (1.0, 0.0-4.0 vs 0.0, 0.0-1.0; p=0.030). The proportion of individuals who require more than 30 minutes to obtain water was correlated with a larger number of BID cases per 105 population in each township (rho=0.28, p=0.006). The number of BID cases was larger in unplanned residential areas, which highlighted the importance of targeted public health interventions specifically to those areas to reduce the total number of COVID-19 associated community deaths in Lusaka. Brought-in-dead surveillance might be beneficial in monitoring epidemic conditions of COVID-19 in such high-risk areas. Furthermore, inadequate access to water, sanitation, and hygiene (WASH) might be associated with such distinct geographical distributions of COVID-19 associated community deaths in Lusaka, Zambia.

Predicting Mortality in Hospitalized COVID-19 Patients in Zambia: An Application of Machine Learning.

The coronavirus disease 2019 (COVID-19) has wreaked havoc globally, resulting in millions of cases and deaths. The objective of this study was to predict mortality in hospitalized COVID-19 patients in Zambia using machine learning (ML) methods based on factors that have been shown to be predictive of mortality and thereby improve pandemic preparedness. This research employed seven powerful ML models that included decision tree (DT), random forest (RF), support vector machines (SVM), logistic regression (LR), Naïve Bayes (NB), gradient boosting (GB), and XGBoost (XGB). These classifiers were trained on 1,433 hospitalized COVID-19 patients from various health facilities in Zambia. The performances achieved by these models were checked using accuracy, recall, F1-Score, area under the receiver operating characteristic curve (ROC_AUC), area under the precision-recall curve (PRC_AUC), and other metrics. The best-performing model was the XGB which had an accuracy of 92.3%, recall of 94.2%, F1-Score of 92.4%, and ROC_AUC of 97.5%. The pairwise Mann-Whitney U-test analysis showed that the second-best model (GB) and the third-best model (RF) did not perform significantly worse than the best model (XGB) and had the following: GB had an accuracy of 91.7%, recall of 94.2%, F1-Score of 91.9%, and ROC_AUC of 97.1%. RF had an accuracy of 90.8%, recall of 93.6%, F1-Score of 91.0%, and ROC_AUC of 96.8%. Other models showed similar results for the same metrics checked. The study successfully derived and validated the selected ML models and predicted mortality effectively with reasonably high performance in the stated metrics. The feature importance analysis found that knowledge of underlying health conditions about patients' hospital length of stay (LOS), white blood cell count, age, and other factors can help healthcare providers offer lifesaving services on time, improve pandemic preparedness, and decongest health facilities in Zambia and other countries with similar settings.

Effectiveness of two doses of Euvichol-plus oral cholera vaccine in response to the 2017/2018 outbreak: a matched case-control study in Lusaka, Zambia.

INTRODUCTION: Zambia experienced a major cholera outbreak in 2017-2018, with more than 5905 cases reported countrywide, predominantly from the peri-urban slums of Lusaka city. The WHO recommends the use of oral cholera vaccines (OCVs) together with traditional control measures, including health promotion, provision of safe water and improving sanitation, in cholera endemic areas and during cholera outbreaks. In response to this outbreak, the Zambian government implemented the OVC campaign and administered the Euvichol-plus vaccine in the high-risk subdistricts of Lusaka. Although OCVs have been shown to be effective in preventing cholera infection in cholera endemic and outbreak settings, the effectiveness of the Euvichol-plus vaccine has not yet been evaluated in Zambia. This study aimed to determine the effectiveness of two doses of OCV administered during the 2017/2018 vaccination campaign. METHODS: We conducted a matched case-control study involving 79 cases and 316 controls following the mass vaccination campaign in the four subdistricts of Lusaka (Chawama, Chipata, Kanyama and Matero). Matching of controls was based on the place of residence, age and sex. Conditional logistic regression was used for analysis. Adjusted OR (AOR), 95% CI and vaccine effectiveness (1-AOR) for two doses of Euvichol-plus vaccine and any dose were estimated (p<0.05). RESULTS: The AOR vaccine effectiveness for two doses of Euvichol-plus OCV was 81.0% (95% CI 66.0% to 78.0%; p<0.01). Secondary analysis showed that vaccine effectiveness for any dose was 74.0% (95% CI 50.0% to 86.0%; p<0.01). CONCLUSION: These findings show that two doses of Euvichol-plus OCV are effective in a cholera outbreak setting in Lusaka, Zambia. The findings also indicate that two doses are more effective than a single dose and thus support the use of two doses of the vaccine as part of an integrated intervention to cholera control during outbreaks.

An evaluation of the Zambia influenza sentinel surveillance system, 2011-2017.

BACKGROUND: Over the past decade, influenza surveillance has been established in several African countries including Zambia. However, information on the on data quality and reliability of established influenza surveillance systems in Africa are limited. Such information would enable countries to assess the performance of their surveillance systems, identify shortfalls for improvement and provide evidence of data reliability for policy making and public health interventions. METHODS: We used the Centers for Disease Control and Prevention guidelines to evaluate the performance of the influenza surveillance system (ISS) in Zambia during 2011-2017 using 9 attributes: (i) data quality and completeness, (ii) timeliness, (iii) representativeness, (iv) flexibility, (v) simplicity, (vi) acceptability, (vii) stability, (viii) utility, and (ix) sustainability. Each attribute was evaluated using pre-defined indicators. For each indicator we obtained the proportion (expressed as percentage) of the outcome of interest over the total. A scale from 1 to 3 was used to provide a score for each attribute as follows: < 60% (as obtained in the calculation above) scored 1 (weak performance); 60-79% scored 2 (moderate performance); ≥80% scored 3 (good performance). An overall score for each attribute and the ISS was obtained by averaging the scores of all evaluated attributes. RESULTS: The overall mean score for the ISS in Zambia was 2.6. Key strengths of the system were the quality of data generated (score: 2.9), its flexibility (score: 3.0) especially to monitor viral pathogens other than influenza viruses, its simplicity (score: 2.8), acceptability (score: 3.0) and stability (score: 2.6) over the review period and its relatively low cost ($310,000 per annum). Identified weaknesses related mainly to geographic representativeness (score: 2.0), timeliness (score: 2.5), especially in shipment of samples from remote sites, and sustainability (score: 1.0) in the absence of external funds. CONCLUSIONS: The system performed moderately well in our evaluation. Key improvements would include improvements in the timeliness of samples shipments and geographical coverage. However, these improvements would result in increased cost and logistical complexity. The ISSS in Zambia is largely reliant on external funds and the acceptability of maintaining the surveillance system through national funds would require evaluation.

Evaluating the costs of cholera illness and cost-effectiveness of a single dose oral vaccination campaign in Lusaka, Zambia.

INTRODUCTION: In 2016, for the very first time, the Ministry of Health in Zambia implemented a reactive outbreak response to control the spread of cholera and vaccinated at-risk populations with a single dose of Shancol-an oral cholera vaccine (OCV). This study aimed to assess the costs of cholera illness and determine the cost-effectiveness of the 2016 vaccination campaign. METHODOLOGY: From April to June 2017, we conducted a retrospective cost and cost-effectiveness analysis in three peri-urban areas of Lusaka. To estimate costs of illness from a household perspective, a systematic random sample of 189 in-patients confirmed with V. cholera were identified from Cholera Treatment Centre registers and interviewed for out-of-pocket costs. Vaccine delivery and health systems costs were extracted from financial records at the District Health Office and health facilities. The cost of cholera treatment was derived by multiplying the subsidized cost of drugs by the quantity administered to patients during hospitalisation. The cost-effectiveness analysis measured incremental cost-effectiveness ratio-cost per case averted, cost per life saved and cost per DALY averted-for a single dose OCV. RESULTS: The mean cost per administered vaccine was US$1.72. Treatment costs per hospitalized episode were US$14.49-US$18.03 for patients ≤15 years old and US$17.66-US$35.16 for older patients. Whereas households incurred costs on non-medical items such as communication, beverages, food and transport during illness, a large proportion of medical costs were borne by the health system. Assuming vaccine effectiveness of 88.9% and 63%, a life expectancy of 62 years and Gross Domestic Product (GDP) per capita of US$1,500, the costs per case averted were estimated US$369-US$532. Costs per life year saved ranged from US$18,515-US$27,976. The total cost per DALY averted was estimated between US$698-US$1,006 for patients ≤15 years old and US$666-US$1,000 for older patients. CONCLUSION: Our study determined that reactive vaccination campaign with a single dose of Shancol for cholera control in densely populated areas of Lusaka was cost-effective.

Acceptance of Cervical Cancer Screening and its Correlates Among Women of a Peri-Urban High-Density Residential Area in Ndola, Zambia.

BACKGROUND: Zambia has one of the highest cervical cancer incidence and mortality rates in the world. Cervical cancer screening leads to reduction in the incidence of invasive disease. The objectives of the study were to determine the level of acceptance of cervical cancer screening and its correlates among women of a peri-urban high-density residential area in Ndola, Zambia. METHODS: A cross sectional study was conducted. With a population size of 12,000 women in reproductive age and using an expected frequency of 50 + 5% and at 95% confidence interval, the required sample size was 372. A stratified sampling method was used to select participants. Independent factors that were associated with the outcome were established using multi-variate logistic regression. Adjusted odds ratios and their 95% confidence intervals are reported. RESULTS: In total, 355 out of 372 questionnaires were administered, achieving a response rate of 95.4%. Out of 355 participants, 9 (2.5%) had ever been screened for cervical cancer. In bivariate analyses, factors associated with screened were knowledge of body part affected, screening as a prevention tool, whether cervical cancer was curable in its early stages or not, awareness of cervical cancer screening, knowledge on frequency of screening and cervical cancer screening causing harm. However, in multivariate analysis, participants who knew that cervical cancer screening prevented cervical cancer were 3.58 (95% CI [1.49, 8.64]) times more likely to have been screened than those who did not have the knowledge. Participants who knew that cervical cancer is curable were 2.76 (95% CI [1.92, 8.31]) times more likely to have been screened than those who did not have the knowledge. CONCLUSION AND GLOBAL HEALTH IMPLICATIONS: The uptake of screening was low. Interventions should be designed to increase uptake of screening for cervical cancer by considering factors that have been identified in the current study that are independently associated with cervical cancer screening among this population.

Cholera Epidemic - Lusaka, Zambia, October 2017-May 2018.

On October 6, 2017, an outbreak of cholera was declared in Zambia after laboratory confirmation of Vibrio cholerae O1, biotype El Tor, serotype Ogawa, from stool specimens from two patients with acute watery diarrhea. The two patients had gone to a clinic in Lusaka, the capital city, on October 4. Cholera cases increased rapidly, from several hundred cases in early December 2017 to approximately 2,000 by early January 2018 (Figure). In collaboration with partners, the Zambia Ministry of Health (MoH) launched a multifaceted public health response that included increased chlorination of the Lusaka municipal water supply, provision of emergency water supplies, water quality monitoring and testing, enhanced surveillance, epidemiologic investigations, a cholera vaccination campaign, aggressive case management and health care worker training, and laboratory testing of clinical samples. In late December 2017, a number of water-related preventive actions were initiated, including increasing chlorine levels throughout the city's water distribution system and placing emergency tanks of chlorinated water in the most affected neighborhoods; cholera cases declined sharply in January 2018. During January 10-February 14, 2018, approximately 2 million doses of oral cholera vaccine were administered to Lusaka residents aged ≥1 year. However, in mid-March, heavy flooding and widespread water shortages occurred, leading to a resurgence of cholera. As of May 12, 2018, the outbreak had affected seven of the 10 provinces in Zambia, with 5,905 suspected cases and a case fatality rate (CFR) of 1.9%. Among the suspected cases, 5,414 (91.7%), including 98 deaths (CFR = 1.8%), occurred in Lusaka residents.

Prevalence and Correlates for Psychosocial Distress Among In-School Adolescents in Zambia.

There is scanty information on correlates for psychosocial distress in Zambia. Secondary analysis was conducted using the data collected in 2004 in Zambia during the global school-based health survey to determine the prevalence and correlates for psychosocial distress. Logistic regression analyses were used to estimate magnitudes of associations between exposure factors and the outcome, while the Yates' corrected Chi-squared test was used to compare proportions at the 5% significance level. A total of 2257 students participated in the survey of which 54.2% were males. Males were generally older than females (p < 0.001). Significantly, more females than males were bullied (p = 0.036), involved in a fight (p = 0.019), and consumed alcohol (p = 0.012). Psychosocial distress was detected in 15.7% of the participants (14.4% of males and 16.8% of females). Age <14 years, male gender, parental support for males, and having close friends were protective factors against psychosocial distress. Risk factors for psychosocial distress were being bullied, involvement in a fight, alcohol consumption, being physically active, and parental support. The prevalence of psychosocial distress among adolescents in Zambia appears to be common. There is a need to validate the psychosocial distress indicators that were used in the current study.

Distribution of yellow fever vectors in Northwestern and Western Provinces, Zambia.

OBJECTIVE: To determine the distribution of yellow fever (YF) vectors species in Northwestern and Western of Zambia, which sampled mosquitoes inside and outside houses in rural, urban, peri-urban and forest areas. METHODS: Back-pack aspirators spray catches and CDC light traps collected adult mosquitoes including 405 Aedes, 518 Anopheles, 471 Culex and 71 Mansonia. Morphological vector identification and PCR viral determination were done at a WHO Regional Reference Centre (Institute Pasteur Dakar), Senegal. RESULTS: The two main YF vectors were Aedes (Stegomyia) aegypti (Ae. aegypti) and Aedes (Stegomyia) africanus. The first was collected in peri-urban areas and the later was in forest areas, both sparsely distributed in Northwestern Province, where the 0.43 Breteau and 1.92 container indexes, respectively implied low risk to YF. Aedes (Aedimorphus) mutilus; Aedes (Aedimorphus) minutus and Aedes (Finlaya) wellmani were also found in Northwestern, not in Western Province. No Aedes were collected from rural peri-domestic areas. Significantly more Aedes species (90.7%, n=398) than Anopheles (9.1%, n=40) were collected in forest areas (P<0.001) or Culex species (0.2%, n=2) (P<0.001). Ae. aegypti was found only in a discarded container but not in flower pots, old tyres, plant axils, discarded shallow wells, disused container bottles and canoes inspected. CONCLUSIONS: Ae. aegypti and Aedes africanus YF vectors were found in the study sites in the Northwestern Province of Zambia, where densities were low and distribution was sparse. The low Breteau index suggests low risk of YF in the Northwestern Province. The presence of Aedes in Northwestern Province and its absence in the Western Province could be due to differing ecological factors in the sampled areas. Universal coverage of vector control interventions could help to reduce YF vector population and the risk to arthropod-borne virus infections.

First sero-prevalence of dengue fever specific immunoglobulin G antibodies in Western and North-Western provinces of Zambia: a population based cross sectional study.

BACKGROUND: Dengue fever is a tropical infectious disease caused by dengue virus (DENV), a single positive-stranded RNA Flavivirus. There is no published evidence of dengue in Zambia. The objective of the study was to determine the sero-prevalence and correlates for dengue fever specific IgG antibodies in Western and North-Western provinces in Zambia. METHODS: A randomized cluster design was used to sample participants for yellow fever risk assessment. In order to rule out cross reactivity with other flaviviruses including dengue, differential antibody tests were done by ELISA. Data was processed using Epi Data version 3.1 and transferred to SPSS version 16.0 for analysis. Bivariate and multivariate analyses were performed to determine the association of dengue fever with various factors. Unadjusted odds ratios (OR), adjusted odds ratios (AOR) and their 95% confidence intervals (CI) are reported. RESULTS: A total of 3,624 persons were sampled for dengue virus infection of whom 53.3% were female and 23.9% were in the 5-14 years age group. Most persons in the survey attained at least primary education (47.6%). No significant association was observed between sex and dengue virus infection (p = 1.000). Overall, 4.1% of the participants tested positive for Dengue IgG. In multivariate analysis, the association of age with Dengue infection showed that those below 5 years of age were 63% (AOR = 0.37; 95% CI [0.16, 0.86]) less likely to be infected with Dengue virus compared to those aged 45 years or older. A significant association was observed between grass thatched roofing and Dengue infection (AOR = 2.28; 95% CI [1.15, 4.53]) Respondents who used Insecticide Treated Nets (ITN) were 21% (AOR = 1.21; 95% CI [1.01, 1.44]) more likely to be infected with dengue infection than those who did not use ITNs. Meanwhile, participants who visited Angola were 73% (AOR = 1.73; 95% CI [1.27, 2.35]) more likely to be infected with Dengue virus than those who did not visit Angola. CONCLUSION: This study provides the first evidence of dengue infection circulation in both North-Western and Western provinces of Zambia. It is important that surveillance activities for Dengue and diagnostic systems are expanded and strengthened, nationwide in order to capture information related to dengue virus and other flaviviruses.

Distribution of yellow fever vectors in Northwestern and Western Provinces, Zambia

Objective: To determine the distribution of yellow fever (YF) vectors species in Northwestern and Western of Zambia, which sampled mosquitoes inside and outside houses in rural, urban, peri-urban and forest areas. Methods: Back-pack aspirators spray catches and CDC light traps collected adult mosquitoes including 405 Aedes, 518 Anopheles, 471 Culex and 71 Mansonia. Morphological vector identification and PCR viral determination were done at a WHO Regional Reference Centre (Institute Pasteur Dakar), Senegal. Results: The two main YF vectors were Aedes (Stegomyia) aegypti (Ae. aegypti) and Aedes (Stegomyia) africanus. The first was collected in peri-urban areas and the later was in forest areas, both sparsely distributed in Northwestern Province, where the 0.43 Breteau and 1.92 container indexes, respectively implied low risk to YF. Aedes (Aedimorphus) mutilus; Aedes (Aedimorphus) minutus and Aedes (Finlaya) wellmani were also found in Northwestern, not in Western Province. No Aedes were collected from rural peri-domestic areas. Significantly more Aedes species (90.7%, n=398) than Anopheles (9.1%, n=40) were collected in forest areas (P<0.001) or Culex species (0.2%, n=2) (P<0.001). Ae. aegypti was found only in a discarded container but not in flower pots, old tyres, plant axils, discarded shallow wells, disused container bottles and canoes inspected. Conclusions: Ae. aegypti and Aedes africanus YF vectors were found in the study sites in the Northwestern Province of Zambia, where densities were low and distribution was sparse. The low Breteau index suggests low risk of YF in the Northwestern Province. The presence of Aedes in Northwestern Province and its absence in the Western Province could be due to differing ecological factors in the sampled areas. Universal coverage of vector control interventions could help to reduce YF vector population and the risk to arthropod-borne virus infections.

Distribution of yellow fever vectors in Northwestern and Western Provinces, Zambia

OBJECTIVE@#To determine the distribution of yellow fever (YF) vectors species in Northwestern and Western of Zambia, which sampled mosquitoes inside and outside houses in rural, urban, peri-urban and forest areas.@*METHODS@#Back-pack aspirators spray catches and CDC light traps collected adult mosquitoes including 405 Aedes, 518 Anopheles, 471 Culex and 71 Mansonia. Morphological vector identification and PCR viral determination were done at a WHO Regional Reference Centre (Institute Pasteur Dakar), Senegal.@*RESULTS@#The two main YF vectors were Aedes (Stegomyia) aegypti (Ae. aegypti) and Aedes (Stegomyia) africanus. The first was collected in peri-urban areas and the later was in forest areas, both sparsely distributed in Northwestern Province, where the 0.43 Breteau and 1.92 container indexes, respectively implied low risk to YF. Aedes (Aedimorphus) mutilus; Aedes (Aedimorphus) minutus and Aedes (Finlaya) wellmani were also found in Northwestern, not in Western Province. No Aedes were collected from rural peri-domestic areas. Significantly more Aedes species (90.7%, n=398) than Anopheles (9.1%, n=40) were collected in forest areas (P<0.001) or Culex species (0.2%, n=2) (P<0.001). Ae. aegypti was found only in a discarded container but not in flower pots, old tyres, plant axils, discarded shallow wells, disused container bottles and canoes inspected.@*CONCLUSIONS@#Ae. aegypti and Aedes africanus YF vectors were found in the study sites in the Northwestern Province of Zambia, where densities were low and distribution was sparse. The low Breteau index suggests low risk of YF in the Northwestern Province. The presence of Aedes in Northwestern Province and its absence in the Western Province could be due to differing ecological factors in the sampled areas. Universal coverage of vector control interventions could help to reduce YF vector population and the risk to arthropod-borne virus infections.