Malawi expected fewer Covid-19 deaths than Europe, USA
At the start of the Covid-19 pandemic, people feared that Africa would have many cases, and that even more people would die than in Europe or the USA. A survey among Malawian health workers however showed that this might not necessarily be so.
Following social distancing rules, and other measures that are supposed to stop the spread of the disease, was easier said than done for people living in poorer countries such as Malawi. Testing facilities were also not adequate.
And, because of other factors such as the prevalence of HIV and AIDS, many experts predicted that Malawi and other African countries would be hard hit by Covid-19.
After the first cases were reported in April 2020 in Malawi, only people showing symptoms were tested. People who were in fact positive yet asymptomatic were never tested. The statistics being gathered did therefore not paint a true picture of the number of Covid-19 cases in the country.
This meant that the local health sector did not have accurate data to prepare for hospital cases and deaths.
Malawian and United Kingdom researchers wanted to get a better sense of the true spread and prevalence of Covid-19 in the country by June 2020. At the time, no formal estimates had yet been done to work out how many healthcare workers in a poor African city had already been exposed to SARS-CoV-19.
Doctors, nurses and clinic staff working in Blantyre, Malawi’s second largest city, were tested. They were chosen because they were frontline workers who were at a high risk of being infected.
They collected blood from 500 healthcare workers who showed no Covid-19 symptoms between 22 May and 19 June 2020. They used a commercially available test to look for traces of SARS-CoV-19 antibodies in these blood samples. This normally indicates whether someone has had the disease yet or not.
In all, 84 participants from across the city tested positive for SARS-CoV-2. That meant that 12,3% knowingly or unknowingly had already contracted Covid-19 in the early phase of the pandemic in Malawi.
By June 2020, SARS-CoV-2 had already unknowingly circulated for some time around all neighbourhoods of Blantyre. Malawi was still in a relatively early phase of the pandemic and could expect a sharp rise in cases. The research team worked out that the number of predicted deaths based on these results were 8 times higher than the number of Covid-19 related deaths actually being reported in the country.
They noted that unlike many previous negative predictions, many people contracting it would most likely be asymptomatic or only suffer mild symptoms.
The findings show how important it is to use local data and local rates when making estimations, because population dynamics differ vastly between countries. The Malawian population, for instance, is much younger than that of Europe.
Despite predictions to the contrary at the start of the pandemic, this research suggested that far fewer Malawians would die because of Covid-19 than for instance people living in China, the Americas and Europe.
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 (HCWs) in Blantyre city to estimate the cumulative incidence of SARS-CoV-2 infection in urban Malawi.
Methods: We recruited 500 otherwise asymptomatic HCWs from Blantyre City (Malawi) from 22nd May 2020 to 19th June 2020 and serum samples were collected from all participants. A commercial ELISA was used to measure SARS-CoV-2 IgG antibodies in serum.
Results: A total of 84 participants tested positive for SARS-CoV-2 antibodies. The HCWs with positive SARS-CoV-2 antibody results came from different parts of the city. The adjusted seroprevalence of SARS-CoV-2 antibodies was 12.3% [CI 8.2 - 16.5]. Using age-stratified infection fatality estimates reported from elsewhere, we found that at the observed adjusted seroprevalence, the number of predicted deaths was eight times the number of reported deaths.
Conclusions: The high seroprevalence of SARS-CoV-2 antibodies among HCWs 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.
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