Abena Serwaa Amoah

Background: Serological data provide important insights into SARS-CoV-2 transmission and immunity, particularly in regions with limited routine surveillance such as sub-Saharan Africa. However, antibody waning and boosting following reinfection or vaccination remain poorly characterised, complicating interpretation of serological measurements. Improved understanding of these dynamics is critical for accurate epidemiological inference. Modelling longitudinal serological data provides a means to quantify antibody kinetics and reconstruct infection histories. Methods: We analysed 15,679 neutralising antibody (nAb) titres from 1,675 unvaccinated, HIV-uninfected participants in urban (Lilongwe) and rural (Karonga) Malawi (February 2021 - April 2022). NAb titres against ancestral B.1, Beta, Delta, and Omicron (BA.1/BA.2) viruses were measured using an HIV-based SARS-CoV-2 pseudotyped virus neutralisation assay. A multi-level Bayesian model was used to reconstruct infection histories and antibody kinetics. Findings: The model identified 429 infections (95% credible interval 417-441), including 39 (9·1%) that had not been identified by traditional seroconversion-based thresholds. Antibody levels waned rapidly, with 48% (0·403-0·560) of the acute boost remaining after three months and only 5% (0·027-0·098) after one year. Pre-Omicron infections generated stronger antibody boosts than Omicron infections. Responses varied, with individuals clustering into low and high responders. Cross-reactive responses extended across substantial antigenic distances - Omicron infections induced broader immunity. Seroincidence was higher in Lilongwe than in Karonga (0·41 vs. 0·27 infections per person per three months), driven by the early 2022 Omicron wave. Reinfections were common, particularly among adults and urban residents. Interpretation: SARS-CoV-2 nAb responses following infection were heterogeneous and declined rapidly. This rapid waning underscores the importance of vaccination for sustained protection, while cross-reactivity suggests only partial immunity from prior variants. Identifying reinfections is essential for understanding transmission and finding populations at higher repeat infection risk, particularly where routine surveillance is limited.

The growing burden of asthma in low- and middle-income countries has been linked to urbanisation and lifestyle changes. However, this burden has not been well characterised in adults. Therefore, we investigated the prevalence of self-reported diagnosed asthma and associated factors in urban and rural adults in Malawi, Southern Africa. Within a cross-sectional population-based survey to determine the burden and risk factors for non-communicable diseases (NCDs) in the city of Lilongwe and rural Karonga district, we collected information on self-reported previously diagnosed asthma and asthma-related symptoms using an interviewer-led questionnaire. Other data collected included: demographic characteristics, socioeconomic status indicators, NCD comorbidities, environmental exposures, and anthropometric measurements. We used multivariable logistic regression models to explore factors associated with self-reported asthma adjusting for variables associated with the outcome in univariable analysis. Findings were corrected for multiple comparisons using the Bonferroni method. We analysed data from 30,483 adult participants (54.6% urban,45.4% rural and 61.9% female). A prior asthma diagnosis was reported in 5.1% of urban and 4.5% of rural participants. In urban females, being obese (>30 kg/m²) compared to normal weight (18.5–24.9 kg/m²) was associated with greater odds of asthma (OR = 1.59, 95% CI [1.26–2.01], p<0.001), after adjusting for confounders. We observed associations between previously diagnosed heart disease and asthma in female participants which remained significant in rural females after Bonferroni correction (OR = 2.30,95%CI [1.32–4.02], p = 0.003). Among rural males, current smokers had reduced odds of diagnosed asthma (OR = 0.46,95%CI [0.27–0.79], p = 0.004) compared to those who had never smoked. In Malawi the prevalence of self-reported diagnosed asthma was greatest in females and urban dwellers. Notably, our findings indicate relationships between excess body weight as well as comorbidities and diagnosed asthma in females. Future investigations using longitudinally collected data and clinical measurements of asthma are needed to better understand these associations.

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.

In low-income Africa, the epidemiology of physical multimorbidity and associated mental health conditions is not well described. We investigated the multimorbidity burden, disease combinations, and relationship between physical multimorbidity and common mental health disorders in rural and urban Malawi using early data from 9,849 adults recruited to an on-going large cross-sectional study on long-term conditions, initiated in 2021. Multimorbidity was defined as having two or more measured (diabetes, hypertension) or self-reported (diabetes, hypertension, disability, chronic pain, HIV, asthma, stroke, heart disease, and epilepsy). Depression and anxiety symptoms were scored using the 9-item Patient Health Questionnaire and 7-item General Anxiety Disorder scale and defined by the total score (range 0–27 and 0–21, respectively). We determined age-standardized multimorbidity prevalence and condition combinations. Additionally, we used multiple linear regression models to examine the association between physical multimorbidity and depression and anxiety symptom scores. Of participants, 81% were rural dwelling, 56% were female, and the median age was 30 years (IQR 21–43). The age-standardized urban and rural prevalence of multimorbidity was 14.1% (95% CI, 12.5–15.8%) and 12.2% (95% CI, 11.6–12.9%), respectively. In adults with two conditions, hypertension, and disability (18%) co-occurred most frequently, and in those with three conditions, hypertension, disability, and chronic pain (23%) were the most common combination. Compared to adults without physical conditions, having one ( B -Coefficient ( B ) 0.78; 95% C1 0.63–0.95%), two-( B 1.36; 95% CI 1.14–1.58%), and three- or more-physical conditions ( B 2.23; 95% CI 1.87–2.59%) were associated with increasing depression score, p -trend <0.001. A comparable ‘dose-response’ relationship was observed between physical multimorbidity and anxiety symptom scores. While the direction of observed associations cannot be determined with these cross-sectional data, our findings highlight the burden of multimorbidity and need for integrating mental and physical health service delivery in Malawi.

Objectives We used the process mapping method and Three Delays framework, to identify and visually represent the relationship between critical actions, decisions and barriers to access to care following injury in the Karonga health system, Northern Malawi. Design Facilitated group process mapping workshops with summary process mapping synthesis. Setting Process mapping workshops took place in 11 identified health system facilities (one per facility) providing injury care for a population in Karonga, Northern Malawi. Participants Fifty-four healthcare workers from various cadres took part. Results An overall injury health system summary map was created using those categories of action, decision and barrier that were sometimes or frequently reported. This provided a visual summary of the process following injury within the health system. For Delay 1 (seeking care) four barriers were most commonly described (by 8 of 11 facilities) these were ‘cultural norms’, ‘healthcare literacy’, ‘traditional healers’ and ‘police processes’. For Delay 2 (reaching care) the barrier most frequently described was ‘transport’—a lack of timely affordable emergency transport (formal or informal) described by all 11 facilities. For Delay 3 (receiving quality care) the most commonly reported barrier was that of ‘physical resources’ (9 of 11 facilities). Conclusions We found our novel approach combining several process mapping exercises to produce a summary map to be highly suited to rapid health system assessment identifying barriers to injury care, within a Three Delays framework. We commend the approach to others wishing to conduct rapid health system assessments in similar contexts.

Schistosoma haematobium is the leading cause of urogenital schistosomiasis and it is recognised as a class 1 carcinogen due to the robust association of infection with bladder cancer. In schistosomes, tetraspanins (TSPs) are abundantly present in different parasite proteomes and could be potential diagnostic candidates due to their accessibility to the host immune system. The large extracellular loops of six TSPs from the secretome (including the soluble excretory/secretory products, tegument and extracellular vesicles) of S. haematobium (Sh-TSP-2, Sh-TSP-4, Sh-TSP-5, Sh-TSP-6, Sh-TSP-18 and Sh-TSP-23) were expressed in a bacterial expression system and polyclonal antibodies were raised to the recombinant proteins to confirm the anatomical sites of expression within the parasite. Sh-TSP-2, and Sh-TSP-18 were identified on the tegument, whereas Sh-TSP-4, Sh-TSP-5, Sh-TSP-6 and Sh-TSP-23 were identified both on the tegument and internal tissues of adult parasites. The mRNAs encoding these TSPs were differentially expressed throughout all schistosome developmental stages tested. The potential diagnostic value of three of these Sh-TSPs was assessed using the urine of individuals (stratified by infection intensity) from an endemic area of Zimbabwe. The three Sh-TSPs were the targets of urine IgG responses in all cohorts, including individuals with very low levels of infection (those positive for circulating anodic antigen but negative for eggs by microscopy). This study provides new antigen candidates to immunologically diagnose S. haematobium infection, and the work presented here provides compelling evidence for the use of a biomarker signature to enhance the diagnostic capability of these tetraspanins.

Background: There are limited data on knowledge and behaviors related to COVID-19 in African countries. Methods: Between April 25 ^th and May 23 ^rd , 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). Results: We 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%). Conclusion: Despite 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?: SARS-CoV-2 is projected to spread widely in African countries. There is limited information about what affected populations know about this new health threat, and how they react to it. What are the new findings?: In 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. These knowledge gaps were larger among residents of rural areas than among urban dwellers. Study 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. Most 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. What do the new findings imply?: Additional information campaigns are needed to address knowledge gaps and misperceptions about SARS-CoV-2/COVID-19 in Malawi.