This study aimed to investigate the characteristics related to SARS-CoV-2 in Luanda, Angola. A total of 622 individuals were screened for SARS-CoV-2 from January to September 2020. Chi-square and logistic regression were used to identify the relationship between sociodemographic characteristics and SARS-CoV-2. Of the 622 tested, 14.3% tested positive. The infection rate was the same for both genders (14.3%). Individuals ≥40 years old, from non-urbanized areas, and healthcare professionals had a higher frequency of infection. The risk of infection was very high in individuals ≥60 years old (AOR: 23.3, 95% CI: 4.83–112), in women (AOR: 1.24, 95% CI: 0.76–2.04), in Luanda (AOR: 7.40, 95% CI: 1.64–33.4), and healthcare professionals (AOR: 1.27, 95% CI: 0.60–2.71), whereas a low risk was observed in individuals from urbanized areas (AOR: 0.44, 95% CI: 0.26–0.75). Our results suggest that Angolan authorities should implement a greater effort in non-urbanized areas and among healthcare professionals since when these individuals presented any indication for a COVID-19 test, such as fever/cough/myalgia, they were more likely to test positive for SARS-CoV-2 than having some other cause for symptoms.

Background SARS-CoV-2 emerged in China and spread throughout the world due to its rapid transmission. The exposure rate in the healthy population is unknown, mainly in resource-limited countries. Herein, we estimated the seroprevalence of anti-SARS-CoV-2 antibodies and risk factors among blood donors in Luanda, the capital city of Angola. Methods This was a retrospective study conducted with 343 blood donors. Chi-square and logistic regression were calculated to predict the independent variable for SARS-CoV-2 infection and deemed significant when p < 0.05. Results Seroprevalence of anti-SARS-CoV-2 was 4.7%. Positivity rates varied to age groups (3.5–14.3%), gender (0–5%), area of residence (3.1–.6%), educational level (5.1–10.2%), occupation (4.4–7.7%), and the blood donor category (2.0–5.1%). Past and recent infections were detected in 3.2% and 1.5%, respectively. Blood donors under the age of 20 years (OR: 4.58, p = 0.241) and from non-urbanized areas (OR: 1.86, p = 0.293) presented a high risk related to infection. The infection was higher in blood group A and lower in blood group O. The risk of SARS-CoV-2 infection has increased from January 2020 (OR: 0.03, p = 0.001) to August 2020 (OR: 0.57, p = 0.426). Conclusions We provide an estimate of the exposure of healthy blood donors in Luanda. Also, we detected anti-SARS-CoV-2 in January 2020, indicating that the SARS-CoV-2 could have been imported during the first month of 2020. Further studies should be performed to assess the exposure rate in different groups from Angola.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in China and spread to the world. 1 Pneumonia caused by SARS-CoV-2 was named coronavirus disease 2019 (COVID-19) and is currently a public health concern. 2,3 From December 2019 to December 2020, more than 60.1 million cases of infection and 1.4 million deaths, have been reported worldwide. 4 Until December 2020, the Ministry of Health of Angola reported more than 15 000 cases and 345 deaths. 4 The timely diagnosis of SARS-CoV-2 infection is fundamental to ensure controlling of the COVID-19 pandemic, the provision of treatment, and to avoid the worsening of the disease. [5][6][7] In practice, RT-PCR is the only way to confirm the SARS-CoV-2. 8 There are individuals that despite being epidemiologically related and presenting pulmonary radiological findings compatible with SARS-CoV-2, remain RT-PCR negative. 9 Factors such as the sample collecting and processing procedure may affect the result of the PCR assay. 10 Also, RT-PCR does not distinguish virus with active replication from residual RNA, which could cause false results, especially in asymptomatic individuals. 10 Therefore, serologic tests offer an alternative to assess the degree of exposure amongst different population groups. 11 There are no published studies that assessed the rate of exposure and immune response to SARS-CoV-2 in Luanda, the capital city of Angola. Herein, we used serological assay to screen IgM and IgG antibodies against SARS-CoV-2 in individuals from Luanda, to support the Ministry of Health of Angola in the management of the COVID-19.

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