The extent and duration of immunity following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are critical outstanding questions about the epidemiology of this novel virus, and studies are needed to evaluate the effects of serostatus on reinfection. Understanding the potential sources of bias and methods for alleviating biases in these studies is important for informing their design and analysis. Confounding by individual-level risk factors in observational studies like these is relatively well appreciated. Here, we show how geographic structure and the underlying, natural dynamics of epidemics can also induce noncausal associations. We take the approach of simulating serological studies in the context of an uncontrolled or controlled epidemic, under different assumptions about whether prior infection does or does not protect an individual against subsequent infection, and using various designs and analytical approaches to analyze the simulated data. We find that in studies assessing whether seropositivity confers protection against future infection, comparing seropositive persons with seronegative persons with similar time-dependent patterns of exposure to infection by stratifying or matching on geographic location and time of enrollment is essential in order to prevent bias.

Electronic health record (EHR) data contain longitudinal patient information and standardized diagnostic codes. EHR data may be useful for estimating transition probabilities for state-transition models, but no guidelines exist on appropriate methods. We applied 3 potential methods to estimate transition probabilities from EHR data, using pediatric eating disorders (EDs) as a case study.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serosurveys provide crucial information on previous SARS-CoV-2 infections in communities. These surveys are particularly useful in low-income and middle-income countries (LMICs), where limited testing capacity inhibits the ability to monitor COVID-19 burden through routine care and contact tracing.

Nowcasting approaches enhance the utility of reportable disease data for trend monitoring by correcting for delays, but implementation details affect accuracy.

There is no agreed methodology for pharmacometric assessment of candidate antiviral drugs in COVID-19. The most widely used measure of virological response in clinical trials so far is the time to viral clearance assessed by qPCR of viral nucleic acid in eluates from serial nasopharyngeal swabs. We posited that the rate of viral clearance would have better discriminatory value. Using a pharmacodynamic model fit to individual SARS-CoV-2 virus clearance data from 46 uncomplicated COVID-19 infections in a cohort of prospectively followed adults, we simulated qPCR viral load data to compare type 2 errors when using time to clearance and rate of clearance under varying antiviral effects, sample sizes, sampling frequencies and durations of follow-up.

Gastric cancer (GC) is a significant global health problem, with Helicobacter pylori infection estimated to be responsible for 89% of non-cardiac GC cases, or 78% of all GC cases. The International Agency for Research on Cancer has called for Helicobacter pylori test-and-treat strategies in countries with high rates of GC. However, for countries with low rates of GC, such as most Western countries, the balance between benefits, harms and costs of screening is less clear-cut. GC is a disease with a well-characterized precancerous process, providing the basis for primary and secondary prevention efforts. However, rigorous data assessing the impact of such interventions in Western countries are lacking. In the absence of clinical trials, modelling offers a unique approach to evaluate the potential impact of various screening and surveillance interventions. In this paper, we provide an overview of modelling studies evaluating the cost-effectiveness of GC screening and surveillance in Western countries.

In today’s era of medical advancement, various modalities of treatment options and dressing materials are available for burn wound management. Bilaminar dermal regeneration template is doubtful in developing countries because of its high cost availability and affordability.

Flexion contracture of finger is a major cause of disability in postburn patients. Various methods have been described to cover the resultant defect after surgical release of finger flexion contracture. Local flaps are used when there is sufficient tissue available on lateral sides of the finger to recruit into the defect. Keystone flap can be designed on volar aspect of finger to cover the post contracture release defect. Use of local flap reduces need of skin graft and donor site morbidity. Here we discuss a case of postburn finger flexion contracture release using type-3 keystone flap. Postoperative results are satisfactory. Various pros and cons of the technique are discussed. Keystone flap is a new addition to the armamentarium of plastic surgeons for release of postburn flexion contracture of fingers.