Using Regional Sero-Epidemiology SARS-CoV-2 Anti-S Antibodies in the Dominican Republic to Inform Targeted Public Health Response.

Incidence of COVID-19 has been associated with sociodemographic factors. We investigated variations in SARS-CoV-2 seroprevalence at sub-national levels in the Dominican Republic and assessed potential factors influencing variation in regional-level seroprevalence. Data were collected in a three-stage cross-sectional national serosurvey from June to October 2021. Seroprevalence of antibodies against the SARS-CoV-2 spike protein (anti-S) was estimated and adjusted for selection probability, age, and sex. Multilevel logistic regression was used to estimate the effect of covariates on seropositivity for anti-S and correlates of 80% protection (PT80) against symptomatic infection for the ancestral and Delta strains. A total of 6683 participants from 134 clusters in all 10 regions were enrolled. Anti-S, PT80 for the ancestral and Delta strains odds ratio varied across regions, Enriquillo presented significant higher odds for all outcomes compared with Yuma. Compared to being unvaccinated, receiving ≥2 doses of COVID-19 vaccine was associated with a significantly higher odds of anti-S positivity (OR 85.94, [10.95-674.33]) and PT80 for the ancestral (OR 4.78, [2.15-10.62]) and Delta strains (OR 3.08, [1.57-9.65]) nationally and also for each region. Our results can help inform regional-level public health response, such as strategies to increase vaccination coverage in areas with low population immunity against currently circulating strains.

Rapid 'mix and read' assay for scalable detection of SARS-CoV-2 antibodies in patient plasma.

The human beta coronavirus SARS-CoV-2, causative virus of COVID-19, has infected more than 15 million people globally and continues to spread. Widespread, population level testing to detect active and past infections is critical to curb the COVID-19 pandemic. Antibody (serological) testing is the only option for detecting past infections outside the narrow window accessible to nucleic acid-based tests. However, currently available serological assays commonly lack scalability. Here, we describe the development of a rapid homogenous serological assay for the detection of antibodies to SARS-CoV-2 in patient plasma. We show that the fluorescence-based assay accurately detects seroconversion in COVID-19 patients from less than 1 microliter of plasma. Using a cohort of samples from COVID-19 infected or healthy individuals, we demonstrate detection with 100% sensitivity and specificity. This assay addresses an important need for a robust, low barrier to implementation, and scalable serological assay with complementary strengths to currently available serological platforms.

Using paired serology and surveillance data to quantify dengue transmission and control during a large outbreak in Fiji.

Dengue is a major health burden, but it can be challenging to examine transmission and evaluate control measures because outbreaks depend on multiple factors, including human population structure, prior immunity and climate. We combined population-representative paired sera collected before and after the 2013/14 dengue-3 outbreak in Fiji with surveillance data to determine how such factors influence transmission and control in island settings. Our results suggested the 10-19 year-old age group had the highest risk of infection, but we did not find strong evidence that other demographic or environmental risk factors were linked to seroconversion. A mathematical model jointly fitted to surveillance and serological data suggested that herd immunity and seasonally varying transmission could not explain observed dynamics. However, the model showed evidence of an additional reduction in transmission coinciding with a vector clean-up campaign, which may have contributed to the decline in cases in the later stages of the outbreak.

Community-associated methicillin-resistant Staphylococcus aureus pyomyositis complicated by compartment syndrome in an immunocompetent young woman.

Pyomyositis is a bacterial infection of skeletal muscle common in the tropics. Pyomyositis has historically been rare in temperate regions. However, the epidemiology is changing, and over the past decade, the number of cases in the United States and Europe has increased significantly. One major factor appears to be the increase in community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) infections. This pathogen now accounts for most of the skin and soft tissue infections throughout much of the United States. Most community-associated MRSA infections carry specific virulence factors, most notably the Panton-Valentine leukocidin gene, known to increase invasive capability and predispose to abscess and deep tissue infections. We report a case of a young healthy woman who was initially treated as an outpatient for tendonitis. She presented 3 days later to the emergency department where she was diagnosed with upper extremity pyomyositis complicated by compartment syndrome. A fasciotomy was performed in the operating room, and intraoperative cultures grew MRSA. She did not have any traditional risk factors for the acquisition of health care-associated MRSA. Her subsequent course was complicated by osteomyelitis of the proximal radius. This is the first report of pyomyositis complicated by compartment syndrome in the emergency medicine literature. This case emphasizes the need to remain vigilant for deep muscle infections given the evolving epidemiology. It also highlights possible complications of pyomyositis including the rare but serious complication of compartment syndrome.