Instruct: Identify the main category of the given Medrxiv paper based on its title.
Query: Effectiveness of COVID-19 vaccines against the Omicron (B.1.1.529) variant of concern
Emergence of the Delta Variant and risk of SARS-CoV-2 infection in secondary school students and staff: prospective surveillance in 18 schools, England
Second versus first wave of COVID-19 deaths: shifts in age distribution and in nursing home fatalities
mRNA vaccines effectiveness against COVID-19 hospitalizations and deaths in older adults: a cohort study based on data-linkage of national health registries in Portugal
Lower Risk of Multisystem Inflammatory Syndrome in Children (MIS-C) with the Delta and Omicron variants of SARS-CoV-2
Intensity of home-based telework and work engagement during the COVID-19 pandemic
A triangulated study on non-pharmacological management of Alzheimer's disease in Mauritius
Sodium intake and high blood pressure among adults on caloric restriction: a multi-year cross-sectional analysis of the U.S. Population, 2007-2018
Prevalence of HIV and Syphilis and their Co-infection among Men Having Sex with Men in Asia: A Systematic Review and Meta-analysis
Spike-antibody responses following first and second doses of ChAdOx1 and BNT162b2 vaccines by age, gender, and clinical factors - a prospective community cohort study (Virus Watch)
Creation and evaluation of full-text literature-derived, feature-weighted disease models of genetically determined developmental disorders
Genome-wide association study and multi-trait analysis of opioid use disorder identifies novel associations in 639,709 individuals of European and African ancestry.
Dissecting heart age using cardiac magnetic resonance videos, electrocardiograms, biobanks, and deep learning
Detection of B.1.351 and B.1.1.7 SARS-CoV-2 variants in Monterrey metropolitan area in Northeast Mexico
Sex differences in brain development in fetuses and infants who are at low or high likelihood for autism
Estimation and interpretation of vaccine efficacy in COVID-19 randomized clinical trials
Assessing the impact of adherence to Non-pharmaceutical interventions and indirect transmission on the dynamics of COVID-19: a mathematical modelling study
Safety and Immunogenicity of Nanocovax, a SARS-CoV-2 Recombinant Spike Protein Vaccine
Validation of a rapid, saliva-based, and ultra-sensitive SARS-CoV-2 screening system for a pandemic-scale infection surveillance
Effectiveness and safety of acupuncture for insulin resistance in women with polycystic ovary syndrome : A systematic review and meta-analysis
Protective effects of HLA-DRB1*04 subtypes in Parkinson's and Alzheimer's diseases implicate acetylated Tau PHF6 sequences
Interleukin-6 as a predictor of early weaning from invasive mechanical ventilation in patients with acute respiratory distress syndrome
Polygenic score for physical activity provides odds for multiple common diseases
Aberrant Activation of the Mentalizing Brain System During Eye Gaze Discrimination in Bipolar Disorder
Antiretroviral therapy associated lipodystrophy; learning from the past.
Longitudinal proteomic profiling of dialysis patients with COVID-19 reveals markers of severity and predictors of death