Nearest Neighbor Gaussian Process for Quantitative Structure-Activity Relationships.

While Gaussian process models are typically restricted to smaller data sets, we propose a variation which extends its applicability to the larger data sets common in the industrial drug discovery space, making it relatively novel in the quantitative structure-activity relationship (QSAR) field. By incorporating locality-sensitive hashing for fast nearest neighbor searches, the nearest neighbor Gaussian process model makes predictions with time complexity that is sub-linear with the sample size. The model can be efficiently built, permitting rapid updates to prevent degradation as new data is collected. Given its small number of hyperparameters, it is robust against overfitting and generalizes about as well as other common QSAR models. Like the usual Gaussian process model, it natively produces principled and well-calibrated uncertainty estimates on its predictions. We compare this new model with implementations of random forest, light gradient boosting, and k-nearest neighbors to highlight these promising advantages. The code for the nearest neighbor Gaussian process is available at https://github.com/Merck/nngp.

Collapsed Dark Matter Structures.

The distributions of dark matter and baryons in the Universe are known to be very different: The dark matter resides in extended halos, while a significant fraction of the baryons have radiated away much of their initial energy and fallen deep into the potential wells. This difference in morphology leads to the widely held conclusion that dark matter cannot cool and collapse on any scale. We revisit this assumption and show that a simple model where dark matter is charged under a "dark electromagnetism" can allow dark matter to form gravitationally collapsed objects with characteristic mass scales much smaller than that of a Milky-Way-type galaxy. Though the majority of the dark matter in spiral galaxies would remain in the halo, such a model opens the possibility that galaxies and their associated dark matter play host to a significant number of collapsed substructures. The observational signatures of such structures are not well explored but potentially interesting.

State Medicaid Coverage and Reimbursement of Adult Vaccines Administered by Physicians and Pharmacists.

Introduction: Effective from October 2023, federal law requires Medicaid programs to cover all recommended adult vaccines administered by physicians with no cost sharing for all eligibility groups. However, uniform coverage does not always translate to optimal uptake. Rather, other factors such as Medicaid reimbursement rates influence vaccine access and ultimately patient uptake. This study reviewed Medicaid policies to understand vaccine coverage and reimbursement, for both physicians and pharmacists, in all 50 U.S. states; Washington, DC; and Puerto Rico (collectively referred to as states). Methods: Between March and September 2022, the researchers reviewed states' public Medicaid policies regarding adult vaccines, focusing on the service of injectable vaccine administration and 3 products: hepatitis A, 9-valent human papilloma virus, and 23-valent pneumococcal polysaccharide. Results: Among 50 states with available data, 7 (14%) restricted Medicaid coverage for hepatitis A, 9-valent human papilloma virus, and/or 23-valent pneumococcal polysaccharide administered by physicians, and 15 (30%) did so for pharmacists. Median physician reimbursement rate was below the private sector rate for hepatitis A (89%) and 9-valent human papilloma virus (94%) but above the rate for 23-valent pneumococcal polysaccharide (108%). Median physician reimbursement for vaccine administration during an office visit was $11.86; the median pharmacist administration fee was $10.67. Conclusions: Although federal law now requires all state Medicaid programs to cover, without cost sharing, all recommended adult vaccines administered by physicians, equitable vaccine access may be hindered by state coverage restrictions for pharmacists and by relatively low reimbursement rates relative to Medicare and commercial coverage for both physicians and pharmacists.

Changes in vaccine administration trends across the life-course during the COVID-19 pandemic in the United States: a claims database study.

BACKGROUND: This study provides an updated and expanded analysis of the impact of the COVID-19 pandemic on routine vaccinations across the life-course in the United States. RESEARCH DESIGN AND METHODS: Routine wellness visits and vaccination rates were calculated using structured claims data for each month during the impact period (January 2020 to August 2022) and compared to the respective baseline period (January 2018 to December 2019). Monthly rates were aggregated as annual accumulated and cumulative percent changes. RESULTS: The complete monthly rate interactive dataset can be viewed at https://vaccinationtrends.com. The greatest decrease in annual accumulated administration rates in the 0-2 and 4-6 years age groups was for the measles, mumps, and rubella vaccine; for adolescents and older adults, it was for human papillomavirus and pneumococcal vaccines, respectively. Routine in-person wellness visit rates recovered faster and more completely than vaccination rates in all age groups, indicating potential missed opportunities to administer vaccines during visits. CONCLUSIONS: This updated analysis reveals that the negative impact of the COVID-19 pandemic on routine vaccination continued through 2021 and into 2022. Proactive efforts to reverse this decline are needed to increase individual- and population-level vaccination coverage and avoid the associated preventable morbidity, mortality, and health care costs.