Instruct: Identify the main category of the given medRxiv paper based on the title.
Query: S-ketamine in patient-controlled analgesia reduces opioid consumption in a dose-dependent manner after major lumbar fusion surgery: a randomized, double-blind, placebo-controlled clinical trial
Evaluation of Pre-operational Factors Contributing to a Dorsal Column Stimulator Explantation
A booster dose of an inactivated SARS-CoV-2 vaccine increases neutralizing antibodies and T cells that recognize Delta and Omicron variants of concern
The demographic and geographic impact of the COVID pandemic in Bulgaria and Eastern Europe in 2020
Evaluation of the Nutritional Quality of Ultra-Processed Foods (Ready to Eat + Fast Food): Fatty Acid Composition
A Multiplex PCR Assay for Identifying All Major SARS-CoV-2 Variants
Efficacy and safety of baricitinib in patients with COVID-19 infection: Results from the randomised, double-blind, placebo-controlled, parallel-group COV-BARRIER phase 3 trial
Validation of a Pancreatic Cancer Detection Test in New-Onset Diabetes Using Cell-Free DNA 5-Hydroxymethylation Signatures
Listening to older voices: results of a cross-sectional survey of older patient-reported experiences of facility-based healthcare in Nouna, Burkina Faso
Comparative evaluation of the transmissibility of SARS-CoV-2 variants of concern
COVID-19 Vaccine Acceptance Among Health Care Workers in the United States
Unraveling the COVID-19 hospitalization dynamics in Spain using publicly available data
Prevalence and risk factors of short birth interval in Bangladesh: Evidence from the linked data of population and health facility survey
Plateaus, rebounds and the effects of individual behaviours in epidemics
Face-to-face interventions to encourage enrolment in cardiac rehabilitation; a scoping review protocol
Large-Scale Hypothesis Testing for Causal Mediation Effects with Applications in Genome-wide Epigenetic Studies
Covid-19 lockdown: Ethnic differences in childrens self-reported physical activity and the importance of leaving the home environment. A longitudinal and cross-sectional
A systematic review and meta-analysis on the safety and efficacy of tocilizumab in the management of COVID-19
EPIDEMIOLOGICAL PROFILE AND CLINICAL CONDITIONS OF WOMEN WITH OR WITHOUT PRECURSORLESION FOR CERVICAL CANCER
Prostate cancer castrate resistant progression usage of non-canonical androgen receptor signaling and ketone body fuel
Individuals with Metabolic Syndrome show altered fecal lipidomic profiles with no signs of intestinal inflammation or increased intestinal permeability: a pilot study
Construction and Validation of a Nomogram Based on the Log Odds of Positive Lymph Nodes to Predict the Prognosis of Lung Neuroendocrine Tumors
Clinical efficacy and increased donor strain engraftment after antibiotic pretreatment in a randomized trial of ulcerative colitis patients receiving fecal microbiota transplant
Secondary Analyses for Genome-wide Association Studies using Expression Quantitative Trait Loci
Estimating typhoid incidence from community-based serosurveys:  A multicohort study in Bangladesh, Nepal, Pakistan and Ghana
A single intramuscular injection of monoclonal antibody MAD0004J08 induces in healthy adults SARS-CoV-2 neutralising antibody titres exceeding those induced by infection and vaccination