In Zanzibar, from the start of the pandemic in March 2020 to the time of sampling in December 2020, SARS-CoV-2 seroprevalence data was limited. We conducted a seroprevalence study to evaluate the magnitude of SARS-CoV-2 exposure among healthcare workers, school children, and people who attended general markets in Zanzibar. The objectives of the study were to analyse the total antibodies from selected higher-risk population groups in order to determine magnitude in SARS CoV-2 exposure. Blood samples were collected from eligible and consented participants (adults and children), and their serum was analyzed for total antibodies against SARS-CoV-2 using ELISA. A questionnaire was used to collect participants’ demographic and clinical data. The overall SARS-CoV-2 seroprevalence across all age groups was 33%, and a higher seroprevalence was observed in the 40 - 49 years’ age group relative to other ages as well as in those who attended markets. A runny nose (18.8% of participants) was the most frequently reported SARS-CoV-2 infection-related symptom. Multivariable analysis showed significantly higher odds of infection in people living in urban districts. The findings provide insight into SARS-CoV-2 infection among school children, health workers, and people who attended markets in Zanzibar in the early stages of the pandemic. Exposure in these groups might have been influenced by infection and prevention strategies taken by the government, as well as shopping behavior, school overcrowding, and population density in urban settings. The study had methodological limitations, including cross-sectional design. Further, well-designed, longitudinal studies are recommended to understand exposure and transmission at a population level.
Wikipedia (2023) COVID-19 Pandemic in Tanzania. https://en.wikipedia.org/w/index.php?title=COVID-19_pandemic_in_Tanzania&oldid=1133385480
[3]
Kangwerema, A., Thomas, H., Knovicks, S., Safari, J., Diluxe, M., Madadi, S., et al. (2021) The Challenge of Dearth of Information in Tanzania’s COVID-19 Response. Journal of Global Health Science, 3, e20. https://doi.org/10.35500/jghs.2021.3.e20
[4]
Salum, S.S., Sheikh, M.A., Hebestreit, A. and Kelm, S. (2022) Anti SARS-CoV-2 Seroprevalence in Zanzibar in 2021 before the Omicron Wave. IJID Regions, 4, 120-122. https://doi.org/10.1016/j.ijregi.2022.06.007
[5]
The United Republic of Tanzania, Ministry of Health (2022) COVID-19 Situation Report: No. 29 from 26th March to 1st April, 2022.
[6]
Unity Studies: Early Investigation Protocols. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technical-guidance/early-investigations
[7]
Isere, E.E., Fatiregun, A.A. and Ajayi, I.O. (2015) An Overview of Disease Surveillance and Notification System in Nigeria and the Roles of Clinicians in Disease Outbreak Prevention and Control. Nigerian Medical Journal, 56, 161-168. https://doi.org/10.4103/0300-1652.160347
[8]
Stringhini, S., Wisniak, A., Piumatti, G., Azman, A.S., Lauer, S.A., Baysson, H., et al. (2020) Seroprevalence of Anti-SARS-CoV-2 IgG Antibodies in Geneva, Switzerland (SEROCoV-POP): A Population-Based Study. The Lancet, 396, 313-319. https://doi.org/10.1016/S0140-6736(20)31304-0
[9]
Public Health Surveillance for COVID-19: Interim Guidance. https://www.who.int/publications-detail-redirect/WHO-2019-nCoV-SurveillanceGuidance-2022.2
[10]
Implications of Tanzania’s Bungled Response to Covid-19. https://www.csis.org/analysis/implications-tanzanias-bungled-response-covid-19
[11]
VIDEO (2021) Tanzania Makes Covid-19 Statistics Public for the First Time in over a Year. The Citizen. https://www.thecitizen.co.tz/tanzania/news/national/video-tanzania-makes-covid-19-statistics-public-for-the-first-time-in-over-a-year-3453900
[12]
Mumbu, A.J. and Hugo, A.K. (2020) Mathematical Modelling on COVID-19 Transmission Impacts with Preventive Measures: A Case Study of Tanzania. Journal of Biological Dynamics, 14, 748-766. https://doi.org/10.1080/17513758.2020.1823494
[13]
Bergeri, I., Whelan, M.G., Ware, H., Subissi, L., Nardone, A., Lewis, H.C., et al. (2022) Global SARS-CoV-2 Seroprevalence from January 2020 to April 2022: A Systematic Review and Meta-Analysis of Standardized Population-Based Studies. PLOS Medicine, 19, e1004107. https://doi.org/10.1371/journal.pmed.1004107
[14]
Earle, K.A., Ambrosino, D.M., Fiore-Gartland, A., Goldblatt, D., Gilbert, P.B., Siber, G.R., et al. (2021) Evidence for Antibody as a Protective Correlate for COVID-19 Vaccines. Vaccine, 39, 4423-4428. https://doi.org/10.1016/j.vaccine.2021.05.063
[15]
Khoury, D.S., Cromer, D., Reynaldi, A., Schlub, T.E., Wheatley, A.K., Juno, J.A., et al. (2021) Neutralizing Antibody Levels Are Highly Predictive of Immune Protection from Symptomatic SARS-CoV-2 Infection. Nature Medicine, 27, 1205-1211. https://doi.org/10.1038/s41591-021-01377-8
[16]
Coronavirus Disease (COVID-19): How Is It Transmitted? https://www.who.int/news-room/questions-and-answers/item/coronavirus-disease-covid-19-how-is-it-transmitted
[17]
Infection Prevention and Control of Epidemic- and Pandemic Prone Acute Respiratory Infections in Health Care. https://www.who.int/publications-detail-redirect/infection-prevention-and-control-of-epidemic-and-pandemic-prone-acute-respiratory-infections-in-health-care
[18]
Chu, D.-T., Singh, V., Vu Ngoc, S.-M., Nguyen, T.-L. and Barceló, D. (2022) Transmission of SARS-CoV-2 Infections and Exposure in Surfaces, Points and Wastewaters: A Global One Health Perspective. Case Studies in Chemical and Environmental Engineering, 5, Article ID: 100184. https://doi.org/10.1016/j.cscee.2022.100184
[19]
Lorenc, A., Kesten, J.M., Kidger, J., Langford, R. and Horwood, J. (2021) Reducing COVID-19 Risk in Schools: A Qualitative Examination of Secondary School Staff and Family Views and Concerns in the South West of England. BMJ Paediatrics Open, 5, e000987. https://doi.org/10.1136/bmjpo-2020-000987
Ministry of Health Zanzibar (2020) Welcome Message. https://mohz.go.tz/eng/wel/
[22]
National Bureau of Statistics (2022) Population and Housing Census—Preliminary Report in Swahili Language. https://www.nbs.go.tz/index.php/en/census-surveys/population-and-housing-census/802-matokeo-ya-mwanzo-ya-sensa-ya-watu-na-makazi-ya-mwaka-2022
[23]
World Health Organization (2020) Coronavirus Disease 2019 (COVID-19): Situation Report, 110. https://apps.who.int/iris/handle/10665/332065
[24]
Covid-19: Tanzania Updates Will Resume after Improvements at National Laboratory. The Citizen. https://www.thecitizen.co.tz/news/Covid-19--Tanzania-updates-will-resume-after-improvements/1840340-5546520-6p8n9nz/index.html
[25]
Covid-19: Zanzibar Cases Rise to 134 after 29 Test Positive. The Citizen. https://www.thecitizen.co.tz/news/Covid-19--Zanzibar-cases-rise-to-134-after-29-test-positive/1840340-5545784-mni388/index.html
[26]
New COVID-19 Variants Fuelling Africa’s Second Wave. WHO|Regional Office for Africa. https://www.afro.who.int/news/new-covid-19-variants-fuelling-africas-second-wave
[27]
Salyer, S.J., Maeda, J., Sembuche, S., Kebede, Y., Tshangela, A., Moussif, M., et al. (2021) The First and Second Waves of the COVID-19 Pandemic in Africa: A Cross-Sectional Study. The Lancet, 397, 1265-1275. https://doi.org/10.1016/S0140-6736(21)00632-2
[28]
Stratton, S.J. (2021) Population Research: Convenience Sampling Strategies. Prehospital and Disaster Medicine, 36, 373-374. https://doi.org/10.1017/S1049023X21000649
[29]
Nyagwange, J., Kutima, B., Mwai, K., Karanja, H.K., Gitonga, J.N., Mugo, D., et al. (2022) Comparative Performance of WANTAI ELISA for Total Immunoglobulin to Receptor Binding Protein and an ELISA for IgG to Spike Protein in Detecting SARS-CoV-2 Antibodies in Kenyan Populations. Journal of Clinical Virology, 146, Article ID: 105061. https://doi.org/10.1016/j.jcv.2021.105061
[30]
Beijing Wantai Biological Pharmacy Enterprise Co., Ltd. (2020) WANTAI SARS-CoV-2 Ab ELISA, Diagnostic Kit for Total Antibody to SARS-CoV-2 (ELISA) V. 2020-02, Instructions for Use. https://www.ystwt.cn/covid-19/
[31]
Chisale, M.R.O., Ramazanu, S., Mwale, S.E., Kumwenda, P., Chipeta, M., Kaminga, A.C., et al. (2022) Seroprevalence of Anti-SARS-CoV-2 Antibodies in Africa: A Systematic Review and Meta-Analysis. Reviews in Medical Virology, 32, e2271. https://doi.org/10.1002/rmv.2271
[32]
Yin, H., Sun, T., Yao, L., Jiao, Y., Ma, L., Lin, L., et al. (2021) Association between Population Density and Infection Rate Suggests the Importance of Social Distancing and Travel Restriction in Reducing the COVID-19 Pandemic. Environmental Science and Pollution Research International, 28, 40424-40430. https://doi.org/10.1007/s11356-021-12364-4
[33]
Bendavid, E., Mulaney, B., Sood, N., Shah, S., Bromley-Dulfano, R., Lai, C., et al. (2021) COVID-19 Antibody Seroprevalence in Santa Clara County, California. International Journal of Epidemiology, 50, 410-419. https://doi.org/10.1093/ije/dyab010
[34]
Poustchi, H., Darvishian, M., Mohammadi, Z., Shayanrad, A., Delavari, A., Bahadorimonfared, A., et al. (2021) SARS-CoV-2 Antibody Seroprevalence in the General Population and High-Risk Occupational Groups across 18 Cities in Iran: A Population-Based Cross-Sectional Study. The Lancet Infectious Diseases, 21, 473-481. https://doi.org/10.1016/S1473-3099(20)30858-6
[35]
Galipeau, Y., Greig, M., Liu, G., Driedger, M. and Langlois, M.-A. (2020) Humoral Responses and Serological Assays in SARS-CoV-2 Infections. Frontiers in Immunology, 11, Article ID: 610688. https://doi.org/10.3389/fimmu.2020.610688
[36]
Demographic Data Project. https://covid19dataproject.org/demographic-data-project/
[37]
Turner, S. (2009) These Young Men Show No Respect for Local Customs—Globalisation and Islamic Revival in Zanzibar. Journal of Religion in Africa, 39, 237-261. https://doi.org/10.1163/002242009X12447135279538
[38]
Affairs BC for R Peace and World. Brittany Gregerson on Islam and Gender Relations in Zanzibar. https://berkleycenter.georgetown.edu/posts/brittany-gregerson-on-islam-and-gender-relations-in-zanzibar
[39]
Lobato, L., Bethony, J.M., Pereira, F.B., Grahek, S.L., Diemert, D. and Gazzinelli, M.F. (2014) Impact of Gender on the Decision to Participate in a Clinical Trial: A Cross-Sectional Study. BMC Public Health, 14, Article No. 1156. https://doi.org/10.1186/1471-2458-14-1156
[40]
Coronavirus Disease (COVID-19): Serology, Antibodies and Immunity. https://www.who.int/news-room/questions-and-answers/item/coronavirus-disease-covid-19-serology
[41]
Jerving, S. (2020) Muddled Messaging around COVID-19 Complicates Response in Tanzania. Devex. https://www.devex.com/news/sponsored/muddled-messaging-around-covid-19-complicates-response-in-tanzania-97590
[42]
Bobrovitz, N., Arora, R.K., Cao, C., Boucher, E., Liu, M., Donnici, C., et al. (2021) Global Seroprevalence of SARS-CoV-2 Antibodies: A Systematic Review and Meta-Analysis. PLOS ONE, 16, e0252617. https://doi.org/10.1371/journal.pone.0252617
[43]
Frost, I., Craig, J., Osena, G., Hauck, S., Kalanxhi, E., Schueller, E., et al. (2021) Modelling COVID-19 Transmission in Africa: Countrywise Projections of Total and Severe Infections under Different Lockdown Scenarios. BMJ Open, 11, e044149. https://doi.org/10.1136/bmjopen-2020-044149
[44]
Ying, F. and O’Clery, N. (2021) Modelling COVID-19 Transmission in Supermarkets Using an Agent-Based Model. PLOS ONE, 16, e0249821. https://doi.org/10.1371/journal.pone.0249821
[45]
Ministry of Education and Vocational Trainings—Department of Pre-Primary and Lower Education. https://moez.go.tz/index.php/department-of-pre-primary-and-lower-education
[46]
Stein-Zamir, C., Abramson, N., Shoob, H., Libal, E., Bitan, M., Cardash, T., et al. (2020) A Large COVID-19 Outbreak in a High School 10 Days after Schools’ Reopening, Israel, May 2020. Eurosurveillance, 25, Article ID: 2001352. https://doi.org/10.2807/1560-7917.ES.2020.25.29.2001352
[47]
European Centre for Disease Prevention and Control (2021) COVID-19 in Children and the Role of School Settings in Transmission—Second Update. https://www.ecdc.europa.eu/en/publications-data/children-and-school-settings-covid-19-transmission
[48]
Questions and Answers on COVID-19: Children Aged 1-18 Years and the Role of School Settings. European Centre for Disease Prevention and Control. https://www.ecdc.europa.eu/en/covid-19/questions-answers/questions-answers-school-transmission
[49]
Schwartz, N.G., Moorman, A.C., Makaretz, A., Chang, K.T., Chu, V.T., Szablewski, C.M., et al. (2020) Adolescent with COVID-19 as the Source of an Outbreak at a 3-Week Family Gathering—Four States, June-July 2020. The Morbidity and Mortality Weekly Report, 69, 1457-1459. https://doi.org/10.15585/mmwr.mm6940e2
[50]
Atherstone, C., Siegel, M., Schmitt-Matzen, E., Sjoblom, S., Jackson, J., Blackmore, C., et al. (2021) SARS-CoV-2 Transmission Associated with High School Wrestling Tournaments—Florida, December 2020-January 2021. The Morbidity and Mortality Weekly Report, 70, 141-143. https://doi.org/10.15585/mmwr.mm7004e4
[51]
Chu, V.T., Yousaf, A.R., Chang, K., Schwartz, N.G., McDaniel, C.J., Lee, S.H., et al. (2021) Household Transmission of SARS-CoV-2 from Children and Adolescents. New England Journal of Medicine, 385, 954-956. https://doi.org/10.1056/NEJMc2031915
[52]
DiBenedetto, D.V. (1995) Occupational Hazards of the Health Care Industry: Protecting Health Care Workers. AAOHN Journal, 43, 131-137. https://doi.org/10.1177/216507999504300303
[53]
Tawiah, P.A., Baffour-Awuah, A., Effah, E.S., Adu-Fosu, G., Ashinyo, M.E., Alhassan, R.K., et al. (2022) Occupational Health Hazards among Healthcare Providers and Ancillary Staff in Ghana: A Scoping Review. BMJ Open, 12, e064499. https://doi.org/10.1136/bmjopen-2022-064499
[54]
Etyang, A.O., Lucinde, R., Karanja, H., Kalu, C., Mugo, D., Nyagwange, J., et al. (2022) Seroprevalence of Antibodies to Severe Acute Respiratory Syndrome Coronavirus 2 among Healthcare Workers in Kenya. Clinical Infectious Diseases, 74, 288-293. https://doi.org/10.1093/cid/ciab346
[55]
Chibwana, M.G., Jere, K.C., Kamng’ona, R., Mandolo, J., Katunga-Phiri, V., Tembo, D., et al. (2020) High SARS-CoV-2 Seroprevalence in Health Care Workers but Relatively Low Numbers of Deaths in Urban Malawi. https://doi.org/10.1101/2020.07.30.20164970
[56]
Sagara, I., Woodford, J., Kone, M., Assadou, M.H., Katile, A., Attaher, O., et al. (2021) Rapidly Increasing SARS-CoV-2 Seroprevalence and Limited Clinical Disease in Three Malian Communities: A Prospective Cohort Study. https://doi.org/10.1101/2021.04.26.21256016
[57]
Mulenga, L.B., Hines, J.Z., Fwoloshi, S., Chirwa, L., Siwingwa, M., Yingst, S., et al. (2021) Prevalence of SARS-CoV-2 in Six Districts in Zambia in July, 2020: A Cross-Sectional Cluster Sample Survey. The Lancet Global Health, 9, e773-e781. https://doi.org/10.1016/S2214-109X(21)00053-X
[58]
Scholz, W. (2006) Challenges of Informal Urbanisation The Case of Zanzibar/ Tanzania.
[59]
Urban Growth Pattern in Western Zanzibar. Quantification and Analysis Using Remote Sensing, GIS and Spatial Metrics. GRIN. https://www.grin.com/document/1139037
[60]
Fofana, M.O., Jr, N.N., Ticona, J.P.A., Belitardo, E.M.M.A., Victoriano, R., Anjos, R.O., et al. (2022) Structural Factors Associated with SARS-CoV-2 Infection Risk in an Urban Slum Setting in Salvador, Brazil: A Cross-Sectional Survey. PLOS Medicine, 19, e1004093. https://doi.org/10.1371/journal.pmed.1004093
[61]
Von Seidlein, L., Alabaster, G., Deen, J. and Knudsen, J. (2021) Crowding Has Consequences: Prevention and Management of COVID-19 in Informal Urban Settlements. Building and Environment, 188, Article ID: 107472. https://doi.org/10.1016/j.buildenv.2020.107472
[62]
Evidence Review: COVID-19 Recovery in South Asian Urban Informal Settlements. Social Science in Humanitarian Action Platform. https://www.socialscienceinaction.org/resources/evidence-review-covid-19-recovery-in-south-asian-urban-informal-settlements/
[63]
Okem, A.E., Makanishe, T.B., Myeni, S.L., Roberts, D.C. and Zungu, S. (2022) A Scoping Review of COVID-19 in the Context of Informal Settlements. Urbanisation, 7, 147-162. https://doi.org/10.1177/24557471221129058
[64]
Nair, D., Raju, R., Roy, S., Dandge, S., Chethrapilly Purushothaman, G.K., Jayaraman, Y., et al. (2022) Sero-Surveillance to Monitor the Trend of SARS-CoV-2 Infection Transmission in India: Study Protocol for a Multi Site, Community Based Longitudinal Cohort Study. Frontiers in Public Health, 10, Article ID: 810353. https://www.frontiersin.org/articles/10.3389/fpubh.2022.810353 https://doi.org/10.3389/fpubh.2022.810353
