tetano
Editor, Senior Moderator
EClinicalMedicine
. 2023 Feb;56:101800.
doi: 10.1016/j.eclinm.2022.101800. Epub 2022 Dec 30.
Omicron B.1.1.529 variant infections associated with severe disease are uncommon in a COVID-19 under-vaccinated, high SARS-CoV-2 seroprevalence population in Malawi
Upendo L Mseka[SUP] 1 2 [/SUP], Jonathan Mandolo[SUP] 1 [/SUP], Kenneth Nyoni[SUP] 2 [/SUP], Oscar Divala[SUP] 2 [/SUP], Dzinkambani Kambalame[SUP] 2 [/SUP], Daniel Mapemba[SUP] 2 [/SUP], Moses Kamzati[SUP] 2 [/SUP], Innocent Chibwe[SUP] 2 [/SUP], Marc Y R Henrion[SUP] 1 3 [/SUP], Kingsley Manda[SUP] 4 [/SUP], Deus Thindwa[SUP] 1 [/SUP], Memory Mvula[SUP] 1 [/SUP], Bright Odala[SUP] 2 [/SUP], Raphael Kamng'ona[SUP] 1 [/SUP], Nelson Dzinza[SUP] 4 [/SUP], Khuzwayo C Jere[SUP] 1 5 6 [/SUP], Nicholas Feasey[SUP] 1 3 [/SUP], Antonia Ho[SUP] 7 [/SUP], Abena S Amoah[SUP] 8 9 [/SUP], Melita Gordon[SUP] 1 5 [/SUP], Todd D Swarthout[SUP] 10 [/SUP], Amelia Crampin[SUP] 7 8 9 [/SUP], Robert S Heyderman[SUP] 10 [/SUP], Matthew Kagoli[SUP] 2 [/SUP], Evelyn Chitsa-Banda[SUP] 2 [/SUP], Collins Mitambo[SUP] 2 [/SUP], John Phuka[SUP] 6 [/SUP], Benson Chilima[SUP] 2 [/SUP], Watipaso Kasambara[SUP] 2 [/SUP], Kondwani C Jambo[SUP] 1 3 6 [/SUP], Annie Chauma-Mwale[SUP] 2 [/SUP]
Affiliations
Abstract
Background: The B.1.1.529 (Omicron) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in the fourth COVID-19 pandemic wave across the southern African region, including Malawi. The seroprevalence of SARS-CoV-2 antibodies and their association with epidemiological trends of hospitalisations and deaths are needed to aid locally relevant public health policy decisions.
Methods: We conducted a population-based serosurvey from December 27, 2021 to January 17, 2022, in 7 districts across Malawi to determine the seroprevalence of SARS-CoV-2 antibodies. Serum samples were tested for antibodies against SARS-CoV-2 receptor binding domain using WANTAI SARS-CoV-2 Receptor Binding Domain total antibody commercial enzyme-linked immunosorbent assay (ELISA). We also evaluated COVID-19 epidemiologic trends in Malawi, including cases, hospitalisations and deaths from April 1, 2021 through April 30, 2022, collected using the routine national COVID-19 reporting system. A multivariable logistic regression model was developed to investigate the factors associated with SARS-CoV-2 seropositivity.
Findings: Serum samples were analysed from 4619 participants (57% female; 60% aged 18-50 years), of whom 878/3794 (23%) of vaccine eligible adults had received a single dose of any COVID-19 vaccine. The overall assay-adjusted seroprevalence was 83.7% (95% confidence interval (CI), 79.3%-93.4%). Seroprevalence was lowest among children <13 years of age (66%) and highest among adults 18-50 years of age (82%). Seroprevalence was higher among vaccinated compared to unvaccinated participants (1 dose, 94% vs. 77%, adjusted odds ratio 4.89 [95% CI, 3.43-7.22]; 2 doses, 97% vs. 77%, aOR 6.62 [95% CI, 4.14-11.3]). Urban residents were more likely to be seropositive than those from rural settings (91% vs. 78%, aOR 2.76 [95% CI, 2.16-3.55]). There was at least a two-fold reduction in the proportion of hospitalisations and deaths among the reported cases in the fourth wave compared to the third wave (hospitalisations, 10.7% (95% CI, 10.2-11.3) vs. 4.86% (95% CI, 4.52-5.23), p < 0.0001; deaths, 3.48% (95% CI, 3.18-3.81) vs. 1.15% (95% CI, 1.00-1.34), p < 0.0001).
Interpretation: We report reduction in proportion of hospitalisations and deaths from SARS-CoV-2 infections during the Omicron variant dominated wave in Malawi, in the context of high SARS-CoV-2 seroprevalence and low COVID-19 vaccination coverage. These findings suggest that COVID-19 vaccination policy in high seroprevalence settings may need to be amended from mass campaigns to targeted vaccination of reported at-risk populations.
Funding: Supported by the Bill and Melinda Gates Foundation (INV-039481).
Keywords: Anti-RBD antibodies; COVID-19; Malawi; Omicron; SARS-CoV-2.
. 2023 Feb;56:101800.
doi: 10.1016/j.eclinm.2022.101800. Epub 2022 Dec 30.
Omicron B.1.1.529 variant infections associated with severe disease are uncommon in a COVID-19 under-vaccinated, high SARS-CoV-2 seroprevalence population in Malawi
Upendo L Mseka[SUP] 1 2 [/SUP], Jonathan Mandolo[SUP] 1 [/SUP], Kenneth Nyoni[SUP] 2 [/SUP], Oscar Divala[SUP] 2 [/SUP], Dzinkambani Kambalame[SUP] 2 [/SUP], Daniel Mapemba[SUP] 2 [/SUP], Moses Kamzati[SUP] 2 [/SUP], Innocent Chibwe[SUP] 2 [/SUP], Marc Y R Henrion[SUP] 1 3 [/SUP], Kingsley Manda[SUP] 4 [/SUP], Deus Thindwa[SUP] 1 [/SUP], Memory Mvula[SUP] 1 [/SUP], Bright Odala[SUP] 2 [/SUP], Raphael Kamng'ona[SUP] 1 [/SUP], Nelson Dzinza[SUP] 4 [/SUP], Khuzwayo C Jere[SUP] 1 5 6 [/SUP], Nicholas Feasey[SUP] 1 3 [/SUP], Antonia Ho[SUP] 7 [/SUP], Abena S Amoah[SUP] 8 9 [/SUP], Melita Gordon[SUP] 1 5 [/SUP], Todd D Swarthout[SUP] 10 [/SUP], Amelia Crampin[SUP] 7 8 9 [/SUP], Robert S Heyderman[SUP] 10 [/SUP], Matthew Kagoli[SUP] 2 [/SUP], Evelyn Chitsa-Banda[SUP] 2 [/SUP], Collins Mitambo[SUP] 2 [/SUP], John Phuka[SUP] 6 [/SUP], Benson Chilima[SUP] 2 [/SUP], Watipaso Kasambara[SUP] 2 [/SUP], Kondwani C Jambo[SUP] 1 3 6 [/SUP], Annie Chauma-Mwale[SUP] 2 [/SUP]
Affiliations
- PMID: 36600885
- PMCID: PMC9800171
- DOI: 10.1016/j.eclinm.2022.101800
Abstract
Background: The B.1.1.529 (Omicron) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in the fourth COVID-19 pandemic wave across the southern African region, including Malawi. The seroprevalence of SARS-CoV-2 antibodies and their association with epidemiological trends of hospitalisations and deaths are needed to aid locally relevant public health policy decisions.
Methods: We conducted a population-based serosurvey from December 27, 2021 to January 17, 2022, in 7 districts across Malawi to determine the seroprevalence of SARS-CoV-2 antibodies. Serum samples were tested for antibodies against SARS-CoV-2 receptor binding domain using WANTAI SARS-CoV-2 Receptor Binding Domain total antibody commercial enzyme-linked immunosorbent assay (ELISA). We also evaluated COVID-19 epidemiologic trends in Malawi, including cases, hospitalisations and deaths from April 1, 2021 through April 30, 2022, collected using the routine national COVID-19 reporting system. A multivariable logistic regression model was developed to investigate the factors associated with SARS-CoV-2 seropositivity.
Findings: Serum samples were analysed from 4619 participants (57% female; 60% aged 18-50 years), of whom 878/3794 (23%) of vaccine eligible adults had received a single dose of any COVID-19 vaccine. The overall assay-adjusted seroprevalence was 83.7% (95% confidence interval (CI), 79.3%-93.4%). Seroprevalence was lowest among children <13 years of age (66%) and highest among adults 18-50 years of age (82%). Seroprevalence was higher among vaccinated compared to unvaccinated participants (1 dose, 94% vs. 77%, adjusted odds ratio 4.89 [95% CI, 3.43-7.22]; 2 doses, 97% vs. 77%, aOR 6.62 [95% CI, 4.14-11.3]). Urban residents were more likely to be seropositive than those from rural settings (91% vs. 78%, aOR 2.76 [95% CI, 2.16-3.55]). There was at least a two-fold reduction in the proportion of hospitalisations and deaths among the reported cases in the fourth wave compared to the third wave (hospitalisations, 10.7% (95% CI, 10.2-11.3) vs. 4.86% (95% CI, 4.52-5.23), p < 0.0001; deaths, 3.48% (95% CI, 3.18-3.81) vs. 1.15% (95% CI, 1.00-1.34), p < 0.0001).
Interpretation: We report reduction in proportion of hospitalisations and deaths from SARS-CoV-2 infections during the Omicron variant dominated wave in Malawi, in the context of high SARS-CoV-2 seroprevalence and low COVID-19 vaccination coverage. These findings suggest that COVID-19 vaccination policy in high seroprevalence settings may need to be amended from mass campaigns to targeted vaccination of reported at-risk populations.
Funding: Supported by the Bill and Melinda Gates Foundation (INV-039481).
Keywords: Anti-RBD antibodies; COVID-19; Malawi; Omicron; SARS-CoV-2.