Current malaria infection, previous malaria exposure, and clinical profiles and outcomes of COVID-19 in a setting of high malaria transmission: an exploratory cohort study in Uganda

The effects of iron deficient and high iron diets on SARS-CoV-2 lung infection and disease

Introduction

The severity of Coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is often dictated by a range of comorbidities. A considerable literature suggests iron deficiency and iron overload may contribute to increased infection, inflammation and disease severity, although direct causal relationships have been difficult to establish.

Methods

Here we generate iron deficient and iron loaded C57BL/6 J mice by feeding standard low and high iron diets, with mice on a normal iron diet representing controls. All mice were infected with a primary SARS-CoV-2 omicron XBB isolate and lung inflammatory responses were analyzed by histology, immunohistochemistry and RNA-Seq.

Results

Compared with controls, iron deficient mice showed no significant changes in lung viral loads or histopathology, whereas, iron loaded mice showed slightly, but significantly, reduced lung viral loads and histopathology. Transcriptional changes were modest, but illustrated widespread dysregulation of inflammation signatures for both iron deficient vs. controls, and iron loaded vs. controls. Some of these changes could be associated with detrimental outcomes, whereas others would be viewed as beneficial.

Discussion

Diet-associated iron deficiency or overload thus induced modest modulations of inflammatory signatures, but no significant histopathologically detectable disease exacerbations.

Cellular immune response to SARS-CoV-2 and clinical presentation in individuals exposed to endemic malaria

Ghana and other parts of West Africa have experienced lower COVID-19 mortality rates than other regions. This phenomenon has been hypothesized to be associated with previous exposure to infections such as malaria. This study investigated the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the influence of previous malaria exposure. Blood samples were collected from individuals with asymptomatic or symptomatic COVID-19 (n = 217). A variety of assays were used to characterize the SARS-CoV-2-specific immune response, and malaria exposure was quantified using Plasmodium falciparum ELISA. The study found evidence of attenuated immune responses to COVID-19 among asymptomatic individuals, with elevated proportions of non-classical monocytes and greater memory B cell activation. Symptomatic patients displayed higher P. falciparum-specific T cell recall immune responses, whereas asymptomatic individuals demonstrated elevated P. falciparum antibody levels. Summarily, this study suggests that P. falciparum exposure-associated immune modulation may contribute to reduced severity of SARS-CoV-2 infection among people living in malaria-endemic regions.

COVID-19 and malaria co-infection: a systematic review of clinical outcomes in endemic areas

Background

COVID-19 and malaria cause significant morbidity and mortality globally. Co-infection of these diseases can worsen their impact on public health. This review aims to synthesize literature on the clinical outcomes of COVID-19 and malaria co-infection to develop effective prevention and treatment strategies.

Methods

A comprehensive literature search was conducted using MeSH terms and keywords from the start of the COVID-19 pandemic to January 2023. The review included original articles on COVID-19 and malaria co-infection, evaluating their methodological quality and certainty of evidence. It was registered in PROSPERO (CRD42023393562).

Results

Out of 1,596 screened articles, 19 met the inclusion criteria. These studies involved 2,810 patients, 618 of whom had COVID-19 and malaria co-infection. Plasmodium falciparum and vivax were identified as causative organisms in six studies. Hospital admission ranged from three to 18 days. Nine studies associated co-infection with severe disease, ICU admission, assisted ventilation, and related complications. One study reported 6% ICU admission, and mortality rates of 3%, 9.4%, and 40.4% were observed in four studies. Estimated crude mortality rates were 10.71 and 5.87 per 1,000 person-days for patients with and without concurrent malaria, respectively. Common co-morbidities included Diabetes mellitus, hypertension, cardiovascular diseases, and respiratory disorders.

Conclusion

Most patients with COVID-19 and malaria co-infection experienced short-term hospitalization and mild to moderate disease severity. However, at presentation, co-morbidities and severe malaria were significantly associated with higher mortality or worse clinical outcomes. These findings emphasize the importance of early detection, prompt treatment, and close monitoring of patients with COVID-19 and malaria co-infection.

IgG Subclass Switch in Volunteers Repeatedly Immunized with the Full-Length Plasmodium falciparum Merozoite Surface Protein 1 (MSP1)

Vaccines are highly effective tools against infectious diseases and are also considered necessary in the fight against malaria. Vaccine-induced immunity is frequently mediated by antibodies. We have recently conducted a first-in-human clinical trial featuring SumayaVac-1, a malaria vaccine based on the recombinant, full-length merozoite surface protein 1 (MSP1FL) formulated with GLA-SE as an adjuvant. Vaccination with MSP1FL was safe and elicited sustainable IgG antibody titers that exceeded those observed in semi-immune populations from Africa. Moreover, IgG antibodies stimulated various Fc-mediated effector mechanisms associated with protection against malaria. However, these functionalities gradually waned. Here, we show that the initial two doses of SumayaVac-1 primarily induced the cytophilic subclasses IgG1 and IgG3. Unexpectedly, a shift in the IgG subclass composition occurred following the third and fourth vaccinations. Specifically, there was a progressive transition to IgG4 antibodies, which displayed a reduced capacity to engage in Fc-mediated effector functions and also exhibited increased avidity. In summary, our analysis of antibody responses to MSP1FL vaccination unveils a temporal shift towards noninflammatory IgG4 antibodies. These findings underscore the importance of considering the impact of IgG subclass composition on vaccine-induced immunity, particularly concerning Fc-mediated effector functions. This knowledge is pivotal in guiding the design of optimal vaccination strategies against malaria, informing decision making for future endeavors in this critical field.

Plasmodium falciparum merozoite surface protein 1 as asexual blood stage malaria vaccine candidate

INTRODUCTION

Malaria represents a public health challenge in tropical and subtropical regions, and currently deployed control strategies are likely insufficient to drive elimination of malaria. Development and improvement of malaria vaccines might be key to reduce disease burden. Vaccines targeting asexual blood stages of the parasite have shown limited efficacy when studied in human trials conducted over the past decades.

AREAS COVERED

Vaccine candidates based on the merozoite surface protein 1 (MSP1) were initially envisioned as one of the most promising approaches to provide immune protection against asexual blood-stage malaria. Successful immunization studies in monkey involved the use of the full-length MSP1 (MSP1FL) as vaccine construct. Vaccines using MSP1FL for immunization have the potential benefit of including numerous conserved B-cell and T-cell epitopes. This could result in improved parasite strain-transcending, protective immunity in the field. We review outcomes of clinical trials that utilized a variety of MSP1 constructs and formulations, including MSP1FL, either alone or in combination with other antigens, in both animal models and humans.

EXPERT OPINION

Novel approaches to analyze breadth and magnitude of effector functions of MSP1-targeting antibodies in volunteers undergoing experimental vaccination and controlled human malaria infection will help to define correlates of protective immunity.

Malaria

Malaria is resurging in many African and South American countries, exacerbated by COVID-19-related health service disruption. In 2021, there were an estimated 247 million malaria cases and 619 000 deaths in 84 endemic countries. Plasmodium falciparum strains partly resistant to artemisinins are entrenched in the Greater Mekong region and have emerged in Africa, while Anopheles mosquito vectors continue to evolve physiological and behavioural resistance to insecticides. Elimination of Plasmodium vivax malaria is hindered by impractical and potentially toxic antirelapse regimens. Parasitological diagnosis and treatment with oral or parenteral artemisinin-based therapy is the mainstay of patient management. Timely blood transfusion, renal replacement therapy, and restrictive fluid therapy can improve survival in severe malaria. Rigorous use of intermittent preventive treatment in pregnancy and infancy and seasonal chemoprevention, potentially combined with pre-erythrocytic vaccines endorsed by WHO in 2021 and 2023, can substantially reduce malaria morbidity. Improved surveillance, better access to effective treatment, more labour-efficient vector control, continued drug development, targeted mass drug administration, and sustained political commitment are required to achieve targets for malaria reduction by the end of this decade.

COVID Perceptions among Pregnant Women Living in a Malaria Hyperendemic Rural Region in Uganda: A Cross-Sectional Study

Both SARS-CoV2 and Plasmodium falciparum infection during pregnancy increases the risk for adverse maternal and fetal outcomes, including abortion, severe disease, and death. Indeed, although malaria and COVID-19 show an overlapping clinical presentation, they require a profoundly different approach. The aim of this study was to explore COVID-19 awareness among pregnant women living in a P. falciparum hyperendemic region in rural Uganda. This cross-sectional, prospective study was conducted in one Hospital and two Health Centers (HC) in Lango region, Uganda, from July 14, 2022, to March 14, 2023. Data about demographics, COVID-19 history, and COVID-19 and malaria perceptions were collected using RedCap mobile app platform. Study endpoint was a context-specific COVID-19 awareness score, accounting for the most common disease misconceptions. Association between study variables and good COVID-19 awareness was assessed by χ2 and t test, as appropriate, and variables found to be statistically significant were further explored in multivariate logistic regression analysis. A total of 888 pregnant women were recruited. Median age was 24 (interquartile range: 20-29) years, whereas 79% (n = 704) attained only primary education and 66.6% (n = 591) were used in agriculture. SARS-CoV2 vaccination rate was 92%. In multivariate analysis (Table 3), variables associated with high COVID knowledge were presenting at antenatal care visit in Atipe HC (adjusted odds ratio [aOR]: 8.1, 95% CI: 4.1-16.48) having a previous good knowledge about malaria (aOR: 1.76, 95% CI: 1.21-2.56). Among pregnant women living in rural Uganda, COVID-19 awareness relies on the overall educational level, malaria knowledge and reference HC. Among pregnant women living in P. falciparum endemic areas, community-level malaria awareness might guide educational interventions during future pandemics.

Malarial Antibodies and Endemicity: Does It Affect SARS-CoV-2 Severity and Outcomes?

Background India has a disproportionately lower rate of coronavirus disease 2019 (COVID-19) severe disease and lower death rates with respect to other parts of the world. It has been proposed that malaria-endemic countries such as India are relatively protected against severe COVID-19 disease and deaths. Methods This was a cross-sectional, analytical, observational study conducted from August 2020 to July 2021 at a tertiary care COVID-19-designated center in New Delhi, India. It aimed to study the association between antimalarial antibody levels and COVID-19 disease severity and outcomes. Results One hundred forty-six patients were included in the final analysis. The mean (standard deviation {SD}) age of the study population was 44.6 (17.2) years, and there were 85 (58.2%) males. Sixty-five patients had mild disease, 14 patients had moderate disease, and 67 patients had severe disease at the time of enrolment in the study. Forty-six patients expired during the hospital stay. For the antimalarial antibody, there was a statistically significant difference between mild and moderate (p=0.018), mild and severe (p=0.016), and mild and combined moderate and severe diseases (p=0.013). However, there was no difference between the patients who survived and those who did not. Conclusion Antimalarial antibody levels may not be associated with the outcomes of COVID-19 during hospital stay. However, this study has provided some insights into the relationship between the severity and outcomes of COVID-19 and the levels of antimalarial antibodies.

Public health priorities for Sino-Africa cooperation in Eastern Africa in context of flooding and malaria burden in Children: a tridecadal retrospective analysis

BACKGROUND

Malaria remains a major public health burden to children under five, especially in Eastern Africa (E.A), -a region that is also witnessing the increasing occurrence of floods and extreme climate change. The present study, therefore, explored the trends in floods, as well as the association of their occurrence and duration with the malaria incidence in children < 5 years in five E.A partner countries of Forum for China-Africa Cooperation (FOCAC), including Ethiopia, Kenya, Somalia, Sudan, and Tanzania between 1990 and 2019.

METHODS

A retrospective analysis of data retrieved from two global sources was performed: the Emergency Events Database (EM-DAT) and the Global Burden of Diseases Study (GBD) between 1990 and 2019. Using SPSS 20.0, a correlation was determined based on ρ= -1 to + 1, as well as the statistical significance of P = < 0.05. Time plots of trends in flooding and malaria incidence were generated in 3 different decades using R version 4.0.

RESULTS

Between 1990 and 2019, the occurrence and duration of floods among the five E.A partner countries of FOCAC increased and showed an upward trend. On the contrary, however, this had an inverse and negative, as well as a weak correlation on the malaria incidence in children under five years. Only Kenya, among the five countries, showed a perfect negative correction of malaria incidence in children under five with flood occurrence (ρ = -0.586**, P-value = 0.001) and duration (ρ = -0.657**, P-value = < 0.0001).

CONCLUSIONS

This study highlights the need for further research to comprehensively explore how different climate extreme events, which oftentimes complement floods, might be influencing the risk of malaria in children under five in five E.A malaria-endemic partner countries of FOCAC. Similarly, it ought to consider investigating the influence of other attributes apart from flood occurrence and duration, which also compound floods like displacement, malnutrition, and water, sanitation and hygiene on the risk and distribution of malaria and other climate-sensitive diseases.

Outcomes of childhood severe malaria: a comparative of study pre-COVID-19 and COVID-19 periods

BACKGROUND

The collateral damages from measures adopted to mitigate the coronavirus disease 2019 (COVID-19) pandemic have been projected to negatively impact malaria in sub-Saharan Africa. Herein, we compare the prevalence and outcomes of childhood severe malaria during the pre-COVID-19 and COVID-19 periods at a tertiary health facility in Nigeria.

METHODS

This was a retrospective review of cases of severe malaria admitted from 1st January to 31st December 2019 (pre-COVID-19 period) and 1st January to 31st December 2020 (COVID-19 period). We extracted relevant information, including demographics, the duration of symptoms before presentation, forms of severe malaria, and outcomes of hospitalization (discharged or death).

RESULTS

In the pre-COVID-19 period, there were a total of 2312 admissions to the EPU and 1685 in the COVID-19 period, representing a decline of 27%. In contrast, there were 263 and 292 severe malaria admissions in the pre-COVID-19 and COVID-19 periods, respectively, representing an 11% increase in the absolute number of cases. The prevalence rates were 11.4% in the pre-COVID-19 period and 17.3% in the COVID-19 period, representing an increase of 52% in the percentage differences. The mortality rate in the COVID-19 period was higher than the pre-COVID-19 period ([10.3%; 30/292 vs. 2.3%; 6/263], p 0.001). The death rate increased by 350% during the COVID-19 period. The odds ratio (OR) of a child dying from severe malaria in the COVID-19 era was 4.9 [95% confidence interval (CI): 2.008 to 11.982]. In the COVID-19 era, presentation at a health facility was also delayed (p = 0.029), as were the odds of multiple features of severe malaria manifestations (OR-1.9, 95% CI, 1.107 to 3.269; p = 0.020).

CONCLUSION

This study shows that the prevalence of severe childhood malaria increased by as much as 11.0%, with a disproportionate increase in mortality compared to the pre-pandemic level. Most children with severe malaria presented late with multiple features of severe malaria, probably contributing to the poor hospitalization outcomes (death) observed in this study.

COVID-19 morbidity in lower versus higher income populations underscores the need to restore lost biodiversity of eukaryotic symbionts

The avoidance of infectious disease by widespread use of 'systems hygiene', defined by hygiene-enhancing technology such as sewage systems, water treatment facilities, and secure food storage containers, has led to a dramatic decrease in symbiotic helminths and protists in high-income human populations. Over a half-century of research has revealed that this 'biota alteration' leads to altered immune function and a propensity for chronic inflammatory diseases, including allergic, autoimmune and neuropsychiatric disorders. A recent Ethiopian study (EClinicalMedicine 39: 101054), validating predictions made by several laboratories, found that symbiotic helminths and protists were associated with a reduced risk of severe COVID-19 (adjusted odds ratio = 0.35; p<0.0001). Thus, it is now apparent that 'biome reconstitution', defined as the artificial re-introduction of benign, symbiotic helminths or protists into the ecosystem of the human body, is important not only for alleviation of chronic immune disease, but likely also for pandemic preparedness.

Exploring SARS-CoV-2 and Plasmodium falciparum coinfection in human erythrocytes

The co-occurrence and the similarities between malaria and COVID-19 diseases raise the question of whether SARS-CoV-2 is capable of infecting red blood cells and, if so, whether these cells represent a competent niche for the virus. In this study, we first tested whether CD147 functions as an alternative receptor of SARS-CoV-2 to infect host cells. Our results show that transient expression of ACE2 but not CD147 in HEK293T allows SARS-CoV-2 pseudoviruses entry and infection. Secondly, using a SARS-CoV-2 wild type virus isolate we tested whether the new coronavirus could bind and enter erythrocytes. Here, we report that 10,94% of red blood cells had SARS-CoV-2 bound to the membrane or inside the cell. Finally, we hypothesized that the presence of the malaria parasite, Plasmodium falciparum, could make erythrocytes more vulnerable to SARS-CoV-2 infection due to red blood cell membrane remodelling. However, we found a low coinfection rate (9,13%), suggesting that P. falciparum would not facilitate the entry of SARS-CoV-2 virus into malaria-infected erythrocytes. Besides, the presence of SARS-CoV-2 in a P. falciparum blood culture did not affect the survival or growth rate of the malaria parasite. Our results are significant because they do not support the role of CD147 in SARS-CoV-2 infection, and indicate, that mature erythrocytes would not be an important reservoir for the virus in our body, although they can be transiently infected.

Seroprevalence of Antibodies to SARS-CoV-2 in Rural Households in Eastern Uganda, 2020-2022

Importance

Estimating the true burden of SARS-CoV-2 infection has been difficult in sub-Saharan Africa owing to asymptomatic infections and inadequate testing capacity. Antibody responses from serologic surveys can provide an estimate of SARS-CoV-2 exposure at the population level.

Objective

To estimate SARS-CoV-2 seroprevalence, attack rates, and reinfection in eastern Uganda using serologic surveillance from 2020 to early 2022.

Design, Setting, and Participants

This cohort study was conducted in the Tororo and Busia districts of eastern Uganda. Plasma samples from participants in the Program for Resistance, Immunology, Surveillance, and Modeling of Malaria in Uganda Border Cohort were obtained at 4 sampling intervals: October to November 2020, March to April 2021, August to September 2021, and February to March 2022. Each participant contributed up to 4 time points for SARS-CoV-2 serology, with almost half of all participants contributing at all 4 time points, and almost 90% contributing at 3 or 4 time points. Information on SARS-CoV-2 vaccination status was collected from participants, with the earliest reported vaccinations in the cohort occurring in May 2021.

Main Outcomes and Measures

The main outcomes of this study were antibody responses to the SARS-CoV-2 spike protein as measured with a bead-based serologic assay. Individual-level outcomes were aggregated to population-level SARS-CoV-2 seroprevalence, attack rates, and boosting rates. Estimates were weighted by the local age distribution according to census data.

Results

A total of 1483 samples from 441 participants living in 76 households were tested. Of the 441 participants, 245 (55.6%) were female, and their mean (SD) age was 16.04 (16.04) years. By the end of the Delta wave and before widespread vaccination, adjusted SARS-CoV-2 seroprevalence was 67.7% (95% credible interval [CrI], 62.5%-72.6%) in the study population. During the subsequent Omicron wave, 84.8% (95% CrI, 67.9%-93.7%) of unvaccinated, previously seronegative individuals were infected for the first time, and 50.8% (95% CrI, 40.6%-59.7%) of unvaccinated, already seropositive individuals were likely reinfected, leading to an overall seropositivity of 96.0% (95% CrI, 93.4%-97.9%) in this population. These results suggest a lower probability of reinfection in individuals with higher preexisting antibody levels. There was evidence of household clustering of SARS-CoV-2 seroconversion. No significant associations were found between SARS-CoV-2 seroconversion and gender, household size, or recent Plasmodium falciparum malaria exposure.

Conclusions and Relevance

In this cohort study in a rural population in eastern Uganda, there was evidence of very high SARS-CoV-2 infection rates throughout the pandemic inconsistent with national level case data and high reinfection rates during the Omicron wave.

Prevalence of SARS-CoV-2 and co-infection with malaria during the first wave of the pandemic (the Burkina Faso case)

Africa accounts for 1.5% of the global coronavirus disease 2019 (COVID-19) cases and 2.7% of deaths, but this low incidence has been partly attributed to the limited testing capacity in most countries. In addition, the population in many African countries is at high risk of infection with endemic infectious diseases such as malaria. Our aim is to determine the prevalence and circulation of SARS-CoV-2 variants, and the frequency of co-infection with the malaria parasite. We conducted serological tests and microscopy examinations on 998 volunteers of different ages and sexes in a random and stratified population sample in Burkina-Faso. In addition, nasopharyngeal samples were taken for RT-qPCR of SARS-CoV-2 and for whole viral genome sequencing. Our results show a 3.2 and a 2.5% of SARS-CoV-2 seroprevalence and PCR positivity; and 22% of malaria incidence, over the sampling period, with marked differences linked to age. Importantly, we found 8 cases of confirmed co-infection and 11 cases of suspected co-infection mostly in children and teenagers. Finally, we report the genome sequences of 13 SARS-CoV-2 isolates circulating in Burkina Faso at the time of analysis, assigned to lineages A.19, A.21, B.1.1.404, B.1.1.118, B.1 and grouped into clades; 19B, 20A, and 20B. This is the first population-based study about SARS-CoV-2 and malaria in Burkina Faso during the first wave of the pandemic, providing a relevant estimation of the real prevalence of SARS-CoV-2 and variants circulating in this Western African country. Besides, it highlights the non-negligible frequency of co-infection with malaria in African communities.

Protozoan co-infections and parasite influence on the efficacy of vaccines against bacterial and viral pathogens

A wide range of protozoan pathogens either transmitted by vectors (Plasmodium, Babesia, Leishmania and Trypanosoma), by contaminated food or water (Entamoeba and Giardia), or by sexual contact (Trichomonas) invade various organs in the body and cause prominent human diseases, such as malaria, babesiosis, leishmaniasis, trypanosomiasis, diarrhea, and trichomoniasis. Humans are frequently exposed to multiple pathogens simultaneously, or sequentially in the high-incidence regions to result in co-infections. Consequently, synergistic or antagonistic pathogenic effects could occur between microbes that also influences overall host responses and severity of diseases. The co-infecting organisms can also follow independent trajectory. In either case, co-infections change host and pathogen metabolic microenvironments, compromise the host immune status, and affect microbial pathogenicity to influence tissue colonization. Immunomodulation by protozoa often adversely affects cellular and humoral immune responses against co-infecting bacterial pathogens and promotes bacterial persistence, and result in more severe disease symptoms. Although co-infections by protozoa and viruses also occur in humans, extensive studies are not yet conducted probably because of limited animal model systems available that can be used for both groups of pathogens. Immunosuppressive effects of protozoan infections can also attenuate vaccines efficacy, weaken immunological memory development, and thus attenuate protection against co-infecting pathogens. Due to increasing occurrence of parasitic infections, roles of acute to chronic protozoan infection on immunological changes need extensive investigations to improve understanding of the mechanistic details of specific immune responses alteration. In fact, this phenomenon should be seriously considered as one cause of breakthrough infections after vaccination against both bacterial and viral pathogens, and for the emergence of drug-resistant bacterial strains. Such studies would facilitate development and implementation of effective vaccination and treatment regimens to prevent or significantly reduce breakthrough infections.

Reconstructing the SARS-CoV-2 epidemic in eastern Uganda through longitudinal serosurveillance in a malaria cohort

Importance

Estimating the true burden of SARS-CoV-2 infection has been difficult in sub-Saharan Africa due to asymptomatic infections and inadequate testing capacity. Antibody responses from serologic surveys can provide an estimate of SARS-CoV-2 exposure at the population level.

Objective

To estimate SARS-CoV-2 seroprevalence, attack rates, and re-infection in eastern Uganda using serologic surveillance from 2020 to early 2022.

Design

Plasma samples from participants in the Program for Resistance, Immunology, Surveillance, and Modeling of Malaria in Uganda (PRISM) Border Cohort were obtained at four sampling intervals: October-November 2020; March-April 2021; August-September 2021; and February-March 2022.

Setting

Tororo and Busia districts, Uganda.

Participants

1,483 samples from 441 participants living in 76 households were tested. Each participant contributed up to 4 time points for SARS-CoV-2 serology, with almost half of all participants contributing at all 4 time points, and almost 90% contributing at 3 or 4 time points. Information on SARS-CoV-2 vaccination status was collected from participants, with the earliest reported vaccinations in the cohort occurring in May 2021.

Main Outcomes and Measures

The main outcomes of this study were antibody responses to the SARS-CoV-2 spike protein as measured with a bead-based serologic assay. Individual-level outcomes were aggregated to population-level SARS-CoV-2 seroprevalence, attack rates, and boosting rates. Estimates were weighted by the local age distribution based on census data.

Results

By the end of the Delta wave and before widespread vaccination, nearly 70% of the study population had experienced SARS-CoV-2 infection. During the subsequent Omicron wave, 85% of unvaccinated, previously seronegative individuals were infected for the first time, and ~50% or more of unvaccinated, already seropositive individuals were likely re-infected, leading to an overall 96% seropositivity in this population. Our results suggest a lower probability of re-infection in individuals with higher pre-existing antibody levels. We found evidence of household clustering of SARS-CoV-2 seroconversion. We found no significant associations between SARS-CoV-2 seroconversion and gender, household size, or recent Plasmodium falciparum malaria exposure.

Conclusions and Relevance

Findings from this study are consistent with very high infection rates and re-infection rates for SARS-CoV-2 in a rural population from eastern Uganda throughout the pandemic.

Non-neutralizing antibodies: Deleterious or propitious during SARS-CoV-2 infection?

Antibody-dependent enhancement (ADE) is a complex phenomenon mediated by antibodies, frequently pre-existing non-neutralizing or sub-neutralizing antibodies. In the course of infectious diseases, ADE may be responsible for worsening the clinical course of the disease by increasing the virulence of pathogens (ADE of infection) or enhancing disease severity (ADE of disease). Here we reviewed the mechanisms thought to be behind the ADE phenomenon and its potential relationship with COVID-19 severity. Since the early COVID-19 epidemics, ADE has been mentioned as a possible mechanism involved in severe COVID-19 disease and, later, as a potential risk in the case of infection after vaccination. However, current data do not support its role in disease severity, both after infection and reinfection.

Recent malaria does not substantially impact COVID-19 antibody response or rates of symptomatic illness in communities with high malaria and COVID-19 transmission in Mali, West Africa

Malaria has been hypothesized as a factor that may have reduced the severity of the COVID-19 pandemic in sub-Saharan Africa. To evaluate the effect of recent malaria on COVID-19 we assessed a subgroup of individuals participating in a longitudinal cohort COVID-19 serosurvey that were also undergoing intensive malaria monitoring as part of antimalarial vaccine trials during the 2020 transmission season in Mali. These communities experienced a high incidence of primarily asymptomatic or mild COVID-19 during 2020 and 2021. In 1314 individuals, 711 were parasitemic during the 2020 malaria transmission season; 442 were symptomatic with clinical malaria and 269 had asymptomatic infection. Presence of parasitemia was not associated with new COVID-19 seroconversion (29.7% (211/711) vs. 30.0% (181/603), p=0.9038) or with rates of reported symptomatic seroconversion during the malaria transmission season. In the subsequent dry season, prior parasitemia was not associated with new COVID-19 seroconversion (30.2% (133/441) vs. 31.2% (108/346), p=0.7499), with symptomatic seroconversion, or with reversion from seropositive to seronegative (prior parasitemia: 36.2% (64/177) vs. no parasitemia: 30.1% (37/119), p=0.3842). After excluding participants with asymptomatic infection, clinical malaria was also not associated with COVID-19 serostatus or symptomatic seroconversion when compared to participants with no parasitemia during the monitoring period. In communities with intense seasonal malaria and a high incidence of asymptomatic or mild COVID-19, we did not demonstrate a relationship between recent malaria and subsequent response to COVID-19. Lifetime exposure, rather than recent infection, may be responsible for any effect of malaria on COVID-19 severity.

Fadelallah Eljack M, Salih EH, Altayeb YFO, Nour AB, Abdallah AM, Osman WAM, Yousif MYE. Clinical characteristics, complications, and predictors of outcome of hospitalized adult Sudanese patients with COVID-19 and malaria coinfection in Sudan: A multicenter retrospective cross-sectional study

Malaria and coronavirus disease 2019 (COVID-19) share several characteristics that could lead to cross-infection, particularly in malaria-endemic areas. Early COVID-19 symptoms might be misdiagnosed for malaria in clinical settings. Also, both diseases can cause fatal complications. So, laboratory testing for both diseases was recommended by the World Health Organization. To study the clinical characteristics and outcomes of Adult Sudanese patients with COVID-19 and malaria coinfection. This retrospective cross-sectional study was conducted from January 2021 to October 2021 in Wad Medani. Total coverage of all Sudanese patients above 18 years old with a confirmed diagnosis of coinfection with COVID-19 and malaria was included, and data were collected using a data collection sheet. Data were analyzed using R software version 4.0.2. Data were described and presented as mean, standard deviation, and number (percentage). To find associated factors with in-hospital outcome, χ2 test, fisher exact test, and independent t test or Wilcoxon rank-sum test were used. In this study, 156 participants were diagnosed with COVID-19 and malaria coinfection. Most of them were between 60 and 70 years (30.8%), the majority were males (59%). Shortness of breath (76.3%) and acute respiratory distress syndrome (35.3%) were the most common symptom and complications among coinfected patients, respectively. Ground glass opacity (n = 47/49, 95.9%) is the most common result for computed tomography scan. Atrial fibrillation was the most common abnormal electrocardiogram finding (n = 6/62, 9.7%). Overall mortality among all participants was (63/156, 40.4%). High mortality rate was found among the coinfected patients. More attention is needed towards fighting COVID-19 and malaria coinfection. There may be a link between malaria and COVID-19.

Co-Infection with Plasmodium vivax and COVID-19 in Thailand

With the emergence of SARS-CoV-2, healthcare systems not only had to address the pressing clinical needs of the COVID-19 pandemic but anticipate the effect on and of other conditions and diseases. This was of particular concern in areas of the world endemic with malaria, a disease which takes hundreds of thousands of lives each year. This case report from Thailand describes a 25-year-old man diagnosed with Plasmodium vivax, who was then found to be co-infected with COVID-19. Both conditions can have overlapping acute febrile illness symptoms which may delay or complicate diagnoses. He had no prior history of malaria and had received two vaccinations against COVID-19. His clinical course was mild with no pulmonary complications or oxygen requirement, and he responded well to treatments for both conditions. Three months after cure, he again contracted COVID-19 but did not experience any P. vivax relapse. Review of the available literature produced less than 10 publications describing co-infections with P. vivax and COVID-19; nonetheless, in endemic areas, vigilance for both diseases should continue, as co-infections could significantly alter the course of clinical management and prognosis as well as affect the healthcare staff caring for these patients.