• Jonathan Mandolo, Jacquline Msefula, Marc Y R Henrion, Comfort Brown, Brewster Moyo, Aubrey Samon, Thandeka Moyo-Gwete, Zanele Makhado, Frances Ayres, Thopisang Motlou, Nonkululeko Mzindle, Newton Kalata, Adamson S Muula, Gaurav Kwatra, Natasha Nsamala, Andrew Likaka, Thom Mfune, Penny L Moore, Bridon Mbaya, Neil French, Robert S Heyderman, Todd Swarthout, and Kondwani C Jambo.
• Malawi-Liverpool-Wellcome Trust Clinical Research Programme (MLW), Blantyre, Malawi.
• Bmc Med. 2021 Nov 19; 19 (1): 303303.

BackgroundBy August 2021, the COVID-19 pandemic has been less severe in sub-Saharan Africa than elsewhere. In Malawi, there have been three subsequent epidemic waves. We therefore aimed to describe the dynamics of SARS-CoV-2 exposure in Malawi.MethodsWe measured the seroprevalence of anti-SARS-CoV-2 antibodies amongst randomly selected blood transfusion donor sera in Malawi from January 2020 to July 2021 using a cross-sectional study design. In a subset, we also assessed in vitro neutralisation against the original variant (D614G WT) and the Beta variant.ResultsA total of 5085 samples were selected from the blood donor database, of which 4075 (80.1%) were aged 20-49 years. Of the total, 1401 were seropositive. After adjustment for assay characteristics and applying population weights, seropositivity reached peaks in October 2020 (18.5%) and May 2021 (64.9%) reflecting the first two epidemic waves. Unlike the first wave, both urban and rural areas had high seropositivity in the second wave, Balaka (rural, 66.2%, April 2021), Blantyre (urban, 75.6%, May 2021), Lilongwe (urban, 78.0%, May 2021), and Mzuzu (urban, 74.6%, April 2021). Blantyre and Mzuzu also show indications of the start of a third pandemic wave with seroprevalence picking up again in July 2021 (Blantyre, 81.7%; Mzuzu, 71.0%). More first wave sera showed in vitro neutralisation activity against the original variant (78% [7/9]) than the beta variant (22% [2/9]), while more second wave sera showed neutralisation activity against the beta variant (75% [12/16]) than the original variant (63% [10/16]).ConclusionThe findings confirm extensive SARS-CoV-2 exposure in Malawi over two epidemic waves with likely poor cross-protection to reinfection from the first on the second wave. The dynamics of SARS-CoV-2 exposure will therefore need to be taken into account in the formulation of the COVID-19 vaccination policy in Malawi and across the region. Future studies should use an adequate sample size for the assessment of neutralisation activity across a panel of SARS-CoV-2 variants of concern/interest to estimate community immunity.© 2021. The Author(s).

13 keywords...

hide…