Analyses of drinking water quality during a protracted cholera epidemic in Malawi - a cross-sectional study of key physicochemical and microbiological parameters

Anecdotal evidence and available literature indicated that contaminated water played a major role in spreading the prolonged cholera epidemic in Malawi from 2022 to 2023. This study assessed drinking water quality in 17 cholera-affected Malawi districts from February to April 2023. Six hundred and thirty-three records were analysed. The median counts/100 ml for thermotolerant coliform was 98 (interquartile range (IQR): 4-100) and that for Escherichia coli was 0 (IQR: 0-9). The drinking water in all (except one) districts was contaminated by thermotolerant coliform, while six districts had their drinking water sources contaminated by E. coli. The percentage of contaminated drinking water sources was significantly higher in shallow unprotected wells (80.0% for E. coli and 95.0% for thermotolerant coliform) and in households (55.8% for E. coli and 86.0% for thermotolerant coliform). Logistic regression showed that household water has three times more risk of being contaminated by E. coli and two and a half times more risk of being contaminated by thermotolerant coliform compared to other water sources. This study demonstrated widespread contamination of drinking water sources during a cholera epidemic in Malawi, which may be the plausible reason for the protracted nature of the epidemic.

Prevalence of Endemic Respiratory Viruses During the COVID-19 Pandemic in Urban and Rural Malawi

Background

We investigated endemic respiratory virus circulation patterns in Malawi, where no lockdown was imposed, during the COVID-19 pandemic.

Methods

Within a prospective household cohort in urban and rural Malawi, adult participants provided upper respiratory tract (URT) samples at 4 time points between February 2021 and April 2022. Polymerase chain reaction (PCR) was performed for SARS-CoV-2, influenza, and other endemic respiratory viruses.

Results

1626 URT samples from 945 participants in 542 households were included. Overall, 7.6% (n = 123) samples were PCR- positive for >1 respiratory virus; SARS-CoV-2 (4.4%) and rhinovirus (2.0%) were most common. No influenza A virus was detected. Influenza B and respiratory syncytial virus (RSV) were rare. Higher virus positivity were detected in the rural setting and at earlier time points. Coinfections were infrequent.

Conclusions

Endemic respiratory viruses circulated in the community in Malawi during the pandemic, though influenza and RSV were rarely detected. Distinct differences in virus positivity and demographics were observed between urban and rural cohorts.

Factors associated with COVID-19 vaccine receipt among mobile phone users in Malawi: Findings from a national mobile-based syndromic surveillance survey, July 2021-April 2022

Malawi recommended COVID-19 vaccines for adults aged ≥18 years in March 2021. We assessed factors associated with receiving COVID-19 vaccines in Malawi as part of a telephone-based syndromic surveillance survey. We conducted telephone-based syndromic surveillance surveys with questions on COVID-19 vaccine receipt among adults (≥18 years old) upon verbal consent from July 2021 to April 2022. We used random digit dialing to select mobile phone numbers and employed electronic data collection forms on secure tablets. Survey questions included whether the respondent had received at least one dose of a COVID-19 vaccine. We used multivariable analysis to identify factors associated with COVID-19 vaccine receipt. Of the 51,577 participants enrolled; 65.7% were male. Males were less likely to receive the COVID-19 vaccine than females (AOR 0.83, 95% CI 0.80-0.86). Compared to those aged 18-24 years, older age had increased odds of vaccine receipt: 25-34 years (AOR 1.32, 95% CI 1.24-1.40), 35-44 years (AOR 2.00, 95% CI 1.88-2.13), 45-54 years (AOR 3.02, 95% CI 2.82-3.24), 55-64 years (AOR 3.24, 95% CI 2.93-3.57) and 65 years+ (AOR 3.98, 95% CI 3.52-4.49). Respondents without formal education were less likely to receive vaccination compared to those with primary (AOR 1.30, 95% CI 1.14-1.48), secondary (AOR 1.76, 95% CI 1.55-2.01), and tertiary (AOR 3.37, 95% CI 2.95-3.86) education. Respondents who thought COVID-19 vaccines were unsafe were less likely to receive vaccination than those who thought it was very safe (AOR 0.26, 95% CI 0.25-0.28). Residents of the Central and Southern regions had reduced odds of vaccine receipt compared to those in the North (AORs 0.79, (95% CI 0.74-0.84) and 0.55, (95% CI 0.52-0.58) respectively). Radio (72.6%), health facilities (52.1%), and social media (16.0%) were the more common self-reported sources of COVID-19 vaccine information. COVID-19 vaccine receipt is associated with gender, age, education, and residence. It is important to consider these factors when implementing COVID-19 vaccination programs.

Characterizing the evolving SARS-CoV-2 seroprevalence in urban and rural Malawi between February 2021 and April 2022: A population-based cohort study

OBJECTIVES

This study aimed to investigate the changing SARS-CoV-2 seroprevalence and associated health and sociodemographic factors in Malawi between February 2021 and April 2022.

METHODS

In total, four 3-monthly serosurveys were conducted within a longitudinal population-based cohort in rural Karonga District and urban Lilongwe, testing for SARS-CoV-2 S1 immunoglobulin (Ig)G antibodies using an enzyme-linked immunosorbent assay. Population seroprevalence was estimated in all and unvaccinated participants. Bayesian mixed-effects logistic models estimated the odds of seropositivity in the first survey, and of seroconversion between surveys, adjusting for age, sex, occupation, location, and assay sensitivity/specificity.

RESULTS

Of the 2005 participants (Karonga, n = 1005; Lilongwe, n = 1000), 55.8% were female and median age was 22.7 years. Between Surveys (SVY) 1 and 4, population-weighted SARS-CoV-2 seroprevalence increased from 26.3% to 89.2% and 46.4% to 93.9% in Karonga and Lilongwe, respectively. At SVY4, seroprevalence did not differ by COVID-19 vaccination status in adults, except for those aged 30+ years in Karonga (unvaccinated: 87.4%, 95% credible interval 79.3-93.0%; two doses: 98.1%, 94.8-99.5%). Location and age were associated with seroconversion risk. Individuals with hybrid immunity had higher SARS-CoV-2 seropositivity and antibody titers, than those infected.

CONCLUSION

High SARS-CoV-2 seroprevalence combined with low morbidity and mortality indicate that universal vaccination is unnecessary at this stage of the pandemic, supporting change in national policy to target at-risk groups.