Household transmission of COVID‐19 among the earliest cases in Antananarivo, Madagascar

Abstract

Background Households are among the highest risk for the transmission of SARS‐CoV‐2. In sub‐Saharan Africa, very few studies have described household transmission during the COVID‐19 pandemic. Our work aimed to describe the epidemiologic parameters and analyze the secondary attack rate (SAR) in Antananarivo, Madagascar, following the introduction of SARS‐CoV‐2 in the country in March 2020. Methods A prospective case‐ascertained study of all identified close contacts of laboratory‐confirmed COVID‐19 infections was conducted in Antananarivo from March to June 2020. Cases and household contacts were followed for 21 days. We estimated epidemic parameters of disease transmission by fitting parametric distributions based on infector‐infected paired data. We assessed factors influencing transmission risk by analyzing the SAR. Findings Overall, we included 96 index cases and 179 household contacts. Adjusted with the best‐fit normal distribution, the incubation period was 4.1 days (95% CI 0.7–7.5]). The serial interval was 6.0 days (95% CI [2.4–9.6]) after adjusting with the best‐fit Weibull distribution. On average, each index case infected 1.6 family members (95%CI [0.9–2.3]). The mean SAR among close contacts was 38.8% (95% CI [19.5–58.2]) with the best‐fit gamma distribution. Contacts older than 35 years old were more likely to be infected, and the highest SAR was found among them. Conclusion The results of our study provide key insights into the epidemiology of the first wave of SARS‐CoV‐2 in Madagascar. High rates of household transmission were found in Antananarivo, emphasizing the need for preventive measures to reduce community transmission.

Household transmission of SARS-CoV-2 from adult index cases living with and without HIV in South Africa, 2020-2021: a case-ascertained, prospective observational household transmission study

“…[14] In a Madagascar study also including both symptomatic and non-symptomatic index cases, HCIR was estimated at 39%. [18] The higher estimate seen in our current study may be influenced by symptom severity, as proposed in previous studies,[19] or the inclusion of only adult index cases, since adult index cases have been shown to result in higher HCIR. [20] In our study, households with index cases older than 35 years were three times more likely to result in higher HCIR compared to when index cases were aged 18-34 years.…”

Household Secondary Attack Rates of SARS-CoV-2 by Variant and Vaccination Status

“…We identified 2097 records (1791 from PubMed, 306 from medRxiv, and 2 from reference lists of eligible articles) published between June 18, 2021, and March 8, 2022 (eFigure 1 in the Supplement ). Fifty-eight new studies 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 (eTable 2 in the Supplement ) were combined with 77 studies from ou...…”

Linear epitope mapping of the humoral response against SARS-CoV-2 in two independent African cohorts

“…Patients from Madagascar were recruited as part of WHO’s First Few X cases (FFX) investigation protocol for coronavirus disease 2019 21 approved by the Ethics Committee of Biomedical Research of the Ministry of Public Health of Madagascar (no. 058/MSANP/SG/AGMED/CERBM, March 30, 2020) 22 , 23 . Written informed consent was obtained from participants before enrolment in this study.…”

“…The retrospective use of these samples for immunological analysis in the context of COVID-19 has been approved by the Senegalese National Ethics Committee for Research in Health (reference number 00000007/MSAS/CNERS/Sec 26 January 2021) and villagers have given their individual consent for this purpose. Samples from COVID-19 RT-PCR positive patients were obtained from a multicentric non-interventional national cohort survey, named SEN-COV 19 22,23 . Written informed consent was obtained from participants before enrolment in this study.…”