Low morbidity and mortality in Africa so far
Seroprevalence of anti-SARS-CoV-2 IgG antibodies in Kenyan blood donors
(KEMRI, Wellcome, London School of Hygiene and Tropical Medicine)
Methods
Measured IgG prevalence
Blood samples from April 30 to June 16, 2020
Account was taken of the non-random sampling
Results
Complete data were available for 3,098 donors
Aged 15-64 years
Crude overall seroprevalence was 5.6%
Population-weighted, test – adjusted national seroprevalence was 5.2%
Seroprevalence was highest in the 3 largest urban Counties – Mombasa, Nairobi, Kisumu
Kenya, population 52m (2.7m infections)
Conclusions
Estimate that 1 in 20 adults in Kenya had SARS-CoV-2 antibodies during the study period
Median date of the survey
Cases, 2093
Deaths, 71 (IFR = 0.0026)
Hospitals not reporting many COVID admissions
Several orders of magnitude difference
High SARS-CoV-2 seroprevalence in health care workers but relatively low numbers of deaths in urban Malawi (Malawi-Liverpool-Wellcome)
Background
In low-income countries
Public health measures difficult
Socioeconomic constraints
Therefore, potential rapid and severe pandemic
Picture so far difficult to access, low testing levels
SARS-CoV-2 serosurvey among health care workers in Blantyre
Estimate the cumulative incidence
Methods
500 otherwise asymptomatic HCWs from Blantyre
22 May 2020 to 19 June 2020
Serum samples were collected from all 500
Results
Eighty four participants tested positive for SARS-CoV-2 antibodies
Who were from different parts of the city
12.3 %
Suggesting that local transmission was high and that virus may have been circulating for some time in Blantyre
Using age – stratified infection fatality estimates reported from elsewhere;
There should have been eight times the number of reported deaths.
Reported number of deaths in Blantyre at the time = 17
Malawi, predicted 5,295 deaths, but 51 reported
Conclusions
High seroprevalence
Discrepancy in the predicted versus reported deaths
Early exposure but slow progression of COVID-19 epidemic in urban Malawi
Mozambique
Survey of 10,000 people in 2 cities, Nampula and Pemba
Antibodies, 3% to 10% of participants
Market vendors, health workers
Mozambique only has 16 confirmed COVID-19 deaths.
Cameroon
Similar reports from Doctors Without Borders
Explanations
Africa misses many more cases due to reduced antigen testing
E.g. Kenya testing about 10% Spain or Canada
Nigeria, testing about 2% that of Spain or Canada
Kenya does not have an overall rise in mortality
South Africa, excess natural deaths, 4 times COVID death figures
Median ages
Spain = 45
Italy = 47
UK = 40.5
Kenya = 20
Malawi = 18
(Africa number may go higher with more rural spread)
? Africans have had more exposure to other coronaviruses
? Regular exposure to malaria or other infectious diseases
? Genetic factors protect the Kenyan population from severe disease.
Research Institute for Development, (France)
Will test thousands for antibodies in Guinea, Senegal, Benin, Ghana, Cameroon, and the Democratic Republic of the Congo
October
Implications
“herd immunity”
Shielding
