International Update, Low morbidity and mortality in Africa

Low morbidity and mortality in Africa so far

https://www.sciencemag.org/news/2020/08/pandemic-appears-have-spared-africa-so-far-scientists-are-struggling-explain-why

Seroprevalence of anti-SARS-CoV-2 IgG antibodies in Kenyan blood donors

(KEMRI, Wellcome, London School of Hygiene and Tropical Medicine)

https://www.medrxiv.org/content/10.1101/2020.07.27.20162693v1.full.pdf

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)

https://www.medrxiv.org/content/10.1101/2020.07.30.20164970v2.full.pdf

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

https://clubofmozambique.com/news/mozambique-2-5-per-cent-of-pemba-population-has-coronavirus-antibodies-167192/

https://www.sciencemag.org/news/2020/08/pandemic-appears-have-spared-africa-so-far-scientists-are-struggling-explain-why

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
https://www.samrc.ac.za/sites/default/files/files/2020-08-05/weekly28July2020.pdf

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)

https://www.who.int/emergencies/diseases/novel-coronavirus-2019/global-research-on-novel-coronavirus-2019-ncov/solidarity-2-global-serologic-study-for-covid-19

Will test thousands for antibodies in Guinea, Senegal, Benin, Ghana, Cameroon, and the Democratic Republic of the Congo

October

Implications

“herd immunity”

Shielding

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