ABSTRACT
BackgroundThe 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. MethodsWe 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. Primary sampling units (PSU) were selected using probability proportionate to the number of households based on the 2018 national census, followed by second-stage sampling units that were selected from listed households. A random systematic sample of households was selected from each PSU within the 7 districts. 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, hospitalizations and deaths from April 1, 2021 through April 30, 2022, collected using the routine national COVID-19 reporting system. ResultsSerum samples were analysed from 4619 participants (57% female; 65% aged 14 to 50 years), of whom 1018 (22%) had received a COVID-19 vaccine. The overall assay-adjusted seroprevalence was 86.3% (95% confidence interval (CI), 85.1% to 87.5%). Seroprevalence was lowest among children <13 years of age (66%) and highest among adults 18 to 50 years of age (82%). Seroprevalence was higher among vaccinated compared to unvaccinated participants (96% vs. 77%; risk ratio, 6.65; 95% CI, 4.16 to 11.40). Urban residents were more likely to test seropositive than those living in rural settings (91% vs. 78%; risk ratio, 2.81; 95% CI, 2.20 to 3.62). National COVID-19 data showed that 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 (hospitalization, 10.7% (95% CI, 10.2 to 11.3) vs 4.86% (95% CI, 4.52 to 5.23), p<0.0001; deaths, 3.48% (95% CI, 3.18 to 3.81) vs 1.15% (95% CI, 1.00 to 1.34), p<0.0001). ConclusionWe 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 but 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 at-risk populations.
ABSTRACT
BackgroundThere are limited data on knowledge and behaviors related to COVID-19 in African countries. MethodsBetween April 25th and May 23rd, we contacted 793 individuals aged 18 and older, who previously participated in studies conducted in the Karonga Health and Demographic Surveillance Site in Malawi. During an interview by mobile phone, we ascertained respondents sources of information about COVID-19 and we evaluated their knowledge of the transmission and course/severity of COVID-19. We also asked them to evaluate their own risks of infection and severe illness. Finally, we inquired about the preventive measures they had adopted in response to the pandemic. We described patterns of knowledge and behaviors by area of residence (rural vs. urban). ResultsWe interviewed 630 respondents (79.5% response rate). Four hundred and eighty-nine respondents resided in rural areas (77.6%) and 141 in urban areas (22.4%). Only one respondent had never heard of COVID-19. Misconceptions about the modes of transmission of SARS-CoV-2, and about the course and severity of COVID-19, were common. For example, 33.2% of respondents believed that the novel coronavirus is also waterborne and 50.6% believed that it is also bloodborne. A large percentage of respondents perceived that there was no risk, or only a small risk, that they would become infected (44.4%), but 72% of respondents expected to be severely ill if they became infected with SARS-CoV-2. Increased hand washing and avoiding crowds were the most reported strategies to prevent the spread of SARS-CoV-2. Use of face masks was more common among urban residents (22.5%) than among rural residents (5.0%). ConclusionDespite widespread access to information about the COVID-19 pandemic, gaps in knowledge about COVID-19 persist in this population. The adoption of preventive strategies remains limited, possibly due to low perceived risk of infection among a large fraction of the population. What is already known?O_LISARS-CoV-2 is projected to spread widely in African countries. C_LIO_LIThere is limited information about what affected populations know about this new health threat, and how they react to it. C_LI What are the new findings?O_LIIn a study in Malawi, respondents lacked knowledge about several aspects of the transmission of SARS-CoV-2, and about the course and severity of COVID-19. C_LIO_LIThese knowledge gaps were larger among residents of rural areas than among urban dwellers. C_LIO_LIStudy respondents perceived themselves at low risk of infection with SARS-CoV-2, but they over-estimated the likely severity of the disease they would experience if they became infected. C_LIO_LIMost respondents reported increased frequency of handwashing, but the adoption of other protective behaviors (e.g., social distancing, use of masks) was limited, particularly in rural areas. C_LI What do the new findings imply?O_LIAdditional information campaigns are needed to address knowledge gaps and misperceptions about SARS-CoV-2/COVID-19 in Malawi. C_LI
