Identification of novelPlasmodium vivaxproteins associated with protection against clinical malaria (preprint)

As progress towards malaria elimination continues, the challenge posed by the parasite species Plasmodium vivax has become more evident. In many regions co-endemic for P. vivax and Plasmodium falciparum , as transmission has declined the proportion of cases due to P. vivax has increased. Novel tools that directly target P. vivax are thus warranted for accelerated elimination. There is currently no advanced vaccine for P. vivax and only a limited number of potential candidates in the pipeline. In this study we aimed to identify promising P. vivax proteins that could be used as part of a subunit vaccination approach. We screened 342 P. vivax protein constructs for their ability to induce IgG antibody responses associated with protection from clinical disease in a cohort of children from Papua New Guinea. This approach has previously been used to successfully identify novel candidates. We were able to confirm previous results from our laboratory identifying the proteins reticulocyte binding protein 2b and StAR-related lipid transfer protein, as well as at least four novel candidates with similar levels of predicted protective efficacy. Assessment of these P. vivax proteins in further studies to confirm their potential and identify functional mechanisms of protection against clinical disease are warranted.

Humoral Immunity to SARS-CoV-2 and Inferred Protection from Infection in a French Longitudinal Community Cohort (preprint)

Population-level immunity to SARS-CoV-2 is growing through vaccination as well as ongoing circulation. Given waning immunity and emergence of new variants, it is important to dynamically determine the risk of re-infection in the population. For estimating immune protection, neutralization titers are most informative, but these assays are difficult to conduct at a population level. Measurement of antibody levels can be implemented at high throughput, but has not been robustly validated as a correlate of protection. Here, we have developed a method that predicts neutralization and protection based on variant-specific antibody measurements to SARS-CoV-2 antigens. This approach allowed us to estimate population-immunity in a longitudinal cohort from France followed for up to 2 years. Participants with a single vaccination or immunity caused by infection only are especially vulnerable to COVID-19 or hospitalization due to SARS-CoV-2. While the median reduced risk to COVID-19 in participants with 3 vaccinations was 96%, the median reduced risk among participants with infection-acquired immunity only was 42%. The results presented here are consistent with data from vaccine-effectiveness studies indicating robustness of our approach. Our multiplex serological assay can be readily optimized and employed to study any new variant and provides a framework for development of an assay that would include protection estimates.

SARS-CoV-2 Omicron neutralization and risk of infection among elderly after a booster dose of Pfizer vaccine (preprint)

Background: The protective immunity against Omicron following a BNT162b2 Pfizer booster dose among elderly is not well characterized. Methods: Thirty-eight residents from three nursing homes were recruited for the study. Antibodies targeting the Spike protein of SARS-CoV-2 were measured with the S-Flow assay. Neutralizing activities in sera were measured as effective dilution 50% (ED50) with the S-Fuse assay using authentic isolates of Delta and Omicron. Results: Among the 38 elderly included in the study, with median (inter-quartile range, IQR) age of 88 (81-92) years, 30 (78.9%) had been previously infected. The ED50 of neutralization were lower against Omicron than Delta, and higher among convalescent compared to naive residents. During an Omicron epidemic affecting two of the three nursing homes in December 2021-January 2022, 75% (6/8) of naive residents got infected, compared to 25% (6/24) of convalescents (P=0.03). Antibody levels to Spike and ED50 of neutralization against Omicron after the BNT162b2 booster dose were lower in those with breakthrough infection (n=12) compared to those without (n=20): median of 1256 vs 2523 BAU/mL (P=0.02) and median ED50 of 234 vs 1298 (P=0.0004), respectively. Conclusion: This study confirmed the importance of receiving at least three antigenic exposures to the SARS-CoV-2 Spike protein for achieving satisfactory neutralizing antibody levels. In this population, protection against Omicron infection was increased in individuals who had been previously infected in addition to the three vaccine doses. Thus, a fourth antigenic exposure may be useful in the elderly population to prevent infection with Omicron, a variant known for its high escape immunity properties.

Strength of Religious Faith in Peruvian Adolescents and Adults: Psychometric Evidence from the Long and Short Version of the Santa Clara Strength of Religious Faith Questionnaire in Spanish (preprint)

The aim of this study was to evaluate the psychometric evidence of the original and brief version of the Santa Clara Strength of Religious Faith Questionnaire (SCSRFQ) in Spanish in a sample of 245 Peruvian adolescents and adults (mean age = 21.04 years, SD = 3.07, 47.8% male and 52.2% female), selected by non-probabilistic convenience sampling. Additionally, the Coronavirus Anxiety Scale and the Satisfaction with Life Scale were applied. Confirmatory Factor Analysis, internal consistency reliability methods, hierarchical sequence of variance models and Graded Response Model were used. Results indicate that both versions of the SCSRFQ showed robust psychometric properties: adequate unidimensional structure, adequate difficulty and discrimination parameters, and significant relationships with the measures of fear of COVID-19 and satisfaction with life. The original version of the SCSRFQ showed evidence of strict measurement invariance by gender and age; whereas the short version showed strict invariance by gender and configural invariance by age. Both versions showed acceptable reliability indices. In conclusion, the original and brief versions of the SCSRFQ show evidence of psychometric indicators that support their use to assess the strength of religious faith

Changes in eating habits and lifestyles in Peruvian population during social isolation by the COVID-19 pandemic (preprint)

Background: The COVID 19 pandemic caused that some governments have implemented house confinement measures with probable consequences on lifestyle, particularly affecting eating habits, physical activity, sleep quality, and mental health. Objectives: The aim of this study was to assess the frequency of lifestyles, physical activity and sleep characteristics, as well as changes in eating habits in the Peruvian population during COVID-19 pandemic. Methods: A Cross-sectional descriptive study was performed. We analyzed adults from Peru between July to August 2020 based on an online self-administered questionnaire divided into sociodemographic, anthropometrics and COVID 19 diagnostic reported, lifestyle habits and frequency of consumption of foods. Findings: During confinement by COVID-19, 1176 participants were studied, 39% were student, 37.5% were workers and 46% were assert not to work. The population asserted gain weight (1 to 3 Kg) and 35.7% were overweight. The lifestyles habits showed that 54.8% affirmed to doing physical activity and a large proportion (37.2%) asserted sleep less. The Peruvian population presented a main feeding patter of breakfast (95.7%), lunch (97.5%), dinner (89.1%) and brunch (44.9%). Likewise, feeding habits before and during COVID-19 pandemic showed that vegetables (OR:1.56, CI95% 1.21 200), fruit (OR: 1.42, CI95% 1.10 1.81), legumes (OR:1.67, CI95% 1.23 2.28) and eggs (OR: 2.00, CI95% 1.52 2.65) presented significantly consumption increase during social isolation, while bakery products (OR: 0.74, CI95% 0.56 0.97), meat, snack, refreshment and fast-food decrease consumption. Other food no significant differences were presented. Conclusion: This study in a Peruvian population showed an important frequency of overweight and sleep disorders. There was a slight increase in physical activity despite the social isolation measures and an increase in health eating habits, nevertheless a majority reported gaining weight.

Rapid Detection of COVID-19 by Serological Methods and the Evaluation of Diagnostic Efficacy of IgM and IgG.

BACKGROUND: In December 2019, a novel coronavirus (SARS-CoV-2) causing symptomatic illness (COVID-19) occurred in Wuhan, China. Travel-associated cases were reported in many other countries leading to epidemic transmission. The number of cases has increased rapidly but laboratory diagnosis is limited. METHODS: We collected samples from two groups of patients diagnosed with COVID-19 for experiments. In one group, 63 serum samples were analyzed IgG and IgM antibodies by enzyme-linked immunosorbent assay (ELISA) and 35 healthy serum samples were served as controls. In the other group, 91 plasma samples were analyzed by colloidal gold-immunochromatographic assay (GICA) for IgG and IgM antibodies and 35 healthy plasma samples were served as controls. Throat swab samples for nucleic acids retest were collected from 81/91 of these participant. RESULTS: The sensitivity of the combined ELISA IgM and IgG detection was 55/63 (87.3%). Sensitivity of the com-bined GICA IgM and IgG detection was 75/91 (82.4%). Both methods were negative for healthy controls and had a specificity of 100%. In 81 cases, the follow up throat swab samples were retested by RT-PCR, showing that 42 cases were positive. The sensitivity was 51.9% (42/81). The area under the receiver operating characteristic (ROC) curve for IgG (AUC(IgG)) was 0.934. The area under the ROC curve for IgM (AUC(IgM)) was 0.812. The area under the ROC curve for IgG + IgM (AUC(IgG+IgM)) was 0.983. CONCLUSIONS: The serological test of SARS-CoV-2 can be used as an important supplement to the existing RT-PCR test for the specific and rapid diagnosis of COVID-19. AUC(IgG) > AUC(IgM) indicates that IgG has better classification performance than IgM. AUC(IgG + IgM) > AUC(IgG) indicates that the combination of IgG and IgM has better classification performance than IgG alone.

Asymptomatic and symptomatic SARS-CoV-2 infections elicit polyfunctional antibodies. (preprint)

A large proportion of SARS-CoV-2 infected individuals remains asymptomatic. Little is known about the extent and quality of their antiviral humoral response. Here, we analyzed antibody functions in 52 asymptomatic infected individuals, 119 mild and 21 hospitalized COVID-19 patients. We measured anti-Spike antibody levels with the S-Flow assay and mapped SARS-CoV-2 Spike- and N-targeted regions by Luminex. Neutralization, complement deposition and Antibody-Dependent Cellular Cytotoxicity (ADCC) were evaluated using replication-competent SARS-CoV-2 or reporter cell systems. We show that COVID-19 sera mediate complement deposition and kill infected cells by ADCC. Sera from asymptomatic individuals neutralize the virus, activate ADCC and trigger complement deposition. Antibody levels and activities are slightly lower in asymptomatic individuals. The different functions of the antibodies are correlated, independently of disease severity. Longitudinal samplings show that antibody functions follow similar kinetics of induction and contraction, with minor variations. Overall, asymptomatic SARS-CoV-2 infection elicits polyfunctional antibodies neutralizing the virus and targeting infected cells. - Sera from convalescent COVID-19 patients activate the complement and kill infected cells by ADCC. - Asymptomatic and symptomatic SARS-CoV-2-infected individuals harbor polyfunctional antibodies. - Antibody levels and functions are slightly lower in asymptomatic individuals - The different antiviral activities of anti-Spike antibodies are correlated regardless of disease severity. - Functions of anti-Spike antibodies have similar kinetics of induction and contraction.

Efficacy and harms of remdesivir for the treatment of COVID-19: a systematic review and meta-analysis (preprint)

Background: We evaluated the efficacy and safety of remdesivir for the treatment of COVID-19. Methods: Systematic review in five engines, pre-print webpages and RCT registries until May 22, 2020 for randomized controlled trials (RCTs) and observational studies evaluating remdesivir on confirmed, COVID-19 adults with pneumonia and/or respiratory insufficiency. Primary outcomes were all-cause mortality, clinical improvement or recovery, need for invasive ventilation, and serious adverse events (SAE). Secondary outcomes included length of hospital stay, progression of pneumonia, and adverse events (AE). Inverse variance random effects meta-analyses were performed. Results: Two placebo-controlled RCTs (n=1300) and two case series (n=88) were included. All studies used remdesivir 200mg IV the first day and 100mg IV for 9 more days, and followed up until 28 days. Wang et al. RCT was stopped early due to AEs; ACTT-1 was preliminary reported at 15-day follow up. Time to clinical improvement was not decreased in Wang et al. RCT, but median time to recovery was decreased by 4 days in ACTT-1. Remdesivir did not decrease all-cause mortality (RR 0.71, 95%CI 0.39 to 1.28) and need for invasive ventilation at 14 days (RR 0.57, 95%CI 0.23 to 1.42), but had fewer SAEs (RR 0.77, 95%CI 0.63 to 0.94). AEs were similar between remdesivir and placebo arms. Risk of bias ranged from some concerns to high risk in RCTs. Interpretation: There is paucity of adequately powered and fully reported RCTs evaluating effects of remdesivir in adult, hospitalized COVID-19 patients. Remdesivir should not be recommended for the treatment of severe COVID-19.