High SARS-CoV-2 seroprevalence in Health Care Workers but relatively low numbers of deaths in urban Malawi

Abstract

Background In low-income countries, like Malawi, important public health measures including social distancing or a lockdown, have been challenging to implement owing to socioeconomic constraints, leading to predictions that the COVID-19 pandemic would progress rapidly. However, due to limited capacity to test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, there are no reliable estimates of the true burden of infection and death. We, therefore, conducted a SARS-CoV-2 serosurvey amongst health care workers (HCW) in Blantyre city to estimate the cumulative incidence of SARS-CoV-2 infection in urban Malawi. Methods Five hundred otherwise asymptomatic HCWs were recruited from Blantyre City (Malawi) from 22nd May 2020 to 19th June 2020 and serum samples were collected all participants. A commercial ELISA was used to measure SARS-CoV-2 IgG antibodies in serum. We run local negative samples (2018 - 2019) to verify the specificity of the assay. To estimate the seroprevalence of SARS CoV-2 antibodies, we adjusted the proportion of positive results based on local specificity of the assay. Results Eighty-four participants tested positive for SARS-CoV-2 antibodies. The HCW with a positive SARS-CoV-2 antibody result came from different parts of the city. The adjusted seroprevalence of SARS-CoV-2 antibodies was 12.3% [CI 9.0-15.7]. Using age-stratified infection fatality estimates reported from elsewhere, we found that at the observed adjusted seroprevalence, the number of predicted deaths was 8 times the number of reported deaths. Conclusion The high seroprevalence of SARS-CoV-2 antibodies among HCW and the discrepancy in the predicted versus reported deaths, suggests that there was early exposure but slow progression of COVID-19 epidemic in urban Malawi. This highlights the urgent need for development of locally parameterised mathematical models to more accurately predict the trajectory of the epidemic in sub-Saharan Africa for better evidence-based policy decisions and public health response planning.

Sub-Saharan Africa preparedness and response to the COVID-19 pandemic: A perspective of early career African scientists

“…These SSA countries issued national guidelines on recommended safety measures, initiated immediate contact tracing, prevented mass gatherings, instituted national lockdown and curfew, closed schools and urged the private sector and the government personnel to work from home. It was noted that Zambia, which did not fully implement the interventions described in this study as well as other countries not included in our review that have struggled to put into action public health interventions 107 , 108 , reported no significant increases in deaths compared to countries with more robust responses reported here. There, consistent with the recent study by M. Njenga et al .…”

Seroprevalence of SARS-CoV-2 antibodies and associated factors in healthcare workers: a systematic review and meta-analysis

“…Mean age of HCWs ranged from 31.2 [ 51 ] years to 47.9 years [ 57 ], while sample size ranged from 25 [ 40 ] to 40,329 HCWs [ 14 ]. Regarding the study design, 26 studies were cross-sectional studies [ 14 , 15 , 18 , 19 , 21 , [23] , [24] , [25] , [27] , [28] , [29] , [30] , [31] , [32] , [34] , [35] , [36] , [37] , 39 , 44 , 47 , 52 , 54 , 58 , 60 , 61 ], 20 studies were prevalence studies [ 17 , 26 , 33 , 38 , [40] , [41] , [42] , [43] , 45 , 46 , [48] , [49] , [50] , [51] , 53 , 55 , 56 , 57 , 59 , 62 ], and three studies were cohort studies [ 16 , 20 , 22 ]. All studies except one [ 31 ] used a convenience sample, while response rate ranged from 47.7% [ 19 ] to 100% [ 36 , 60 ].…”

“…All studies except one [ 31 ] used a convenience sample, while response rate ranged from 47.7% [ 19 ] to 100% [ 36 , 60 ]. Forty-two studies were conducted in hospitals [ [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , 26 , 27 , [29] , [30] , [31] , [32] , [33] , [34] , [35] , [36] , [37] , [38] , [39] , [40] , [41] , [42] , [43] , [44] , [45] , [46] , [47] , [48] , [50] , [51] , [52] , [53] , [54] , [55] , [56] , [57] , [58] , [59] , [60] , [61] , [62] ], four studies in primary care facilities and hospitals [ 14 , 25 , 28 , 49 ], two studies in primary care facilities [ 35 , 62 ] and one study in cancer centers [ 59 ]. Thirty-five studies were published in journals [ [14] , [15] , [16] , [17] , [18] , [19] , [20] , <...>…”

A high-throughput microfluidic nano-immunoassay for detecting anti-SARS-CoV-2 antibodies in serum or ultra-low volume dried blood samples

“…Further areas of use could be large-scale seroprevalence studies in low-and middle-income countries[28] without sufficient in-country laboratory capacity by sending specimens by international mail. Especially in the current SARS-CoV-2 pandemic, population-based seroprevalence studies could elucidate some urgent questions such as the impact of COVID-19 in Africa[29].New technology and method developments such as those reported here will make it possible to overcome the current centralized molecular diagnostics paradigm, which is focused on hospitals and point of care settings rather than on patients and individuals seeking simple, affordable, and convenient molecular…”