The OPTN defines high risk donors (HRDs), colloquially known as 'CDC high risk donors' , as those thought to carry an increased risk of HIV window period (WP) infection prior to serologic detectability. However, the true risk of such infection remains unknown. To quantify the risk of WP infection in each HRD behavior category, we performed a systematic review and metaanalysis of studies of HIV prevalence and incidence. Of 3476 abstracts reviewed, 27 eligible studies of HIV infection in HRD populations were identified. Pooled HIV incidence estimates were calculated for each category of HRD behavior and used to calculate the risk of WP HIV infection. Risks ranged from 0.09-12.1 per 10 000 donors based on WP for ELISA and 0.04-4.9 based on nucleic acid testing (NAT), with NAT reducing WP risk by over 50% in each category. Injection drug users had the greatest risk of WP infection (4.9 per 10 000 donors by NAT WP), followed by men who have sex with men (4.2:10 000), commercial sex workers (2.7:10 000), incarcerated donors (0.9:10 000), donors exposed to HIV through blood (0.6:10 000), donors engaging in highrisk sex (0.3:10 000) and hemophiliacs (0.035:10 000). These estimates can help inform patient and provider decision making regarding HRDs.

The OPTN classifies high infectious risk donors (HRDs) based on criteria originally intended to identify people at risk for HIV infection. These donors are sometimes referred to as 'CDC high risk donors' in reference to the CDC-published guidelines adopted by the OPTN. However, these guidelines are also being used to identify deceased donors at increased risk of window period (WP) hepatitis C virus (HCV) infection, although not designed for this purpose. The actual risk of WP HCV infection in HRDs is unknown. We performed a systematic review of 3476 abstracts and identified 37 eligible estimates of HCV incidence in HRD populations in the United States/Canada. Pooled HCV incidence was derived and used to estimate the risk of WP infection for each HRD category. Risks ranged from 0.26 to 300.6 per 10 000 donors based on WP for ELISA and 0.027 to 32.4 based on nucleic acid testing (NAT). Injection drug users were at highest risk (32.4 per 10 000 donors by NAT WP), followed by commercial sex workers and donors exhibiting high risk sexual behavior (12.3 per 10 000), men who have sex with men (3.5 per 10 000), incarcerated donors (0.8 per 10 000), donors exposed to HIV infected blood (0.4 per 10 000) and hemophiliacs (0.027 per 10 000). NAT reduced WP risk by approximately 10-fold in each category.

Objective We aimed to estimate the incidence of cerebral sinus and venous thrombosis (CVT) within 1 month from first dose administration and the frequency of vaccine‐induced immune thrombotic thrombocytopenia (VITT) as the underlying mechanism after vaccination with BNT162b2, ChAdOx1, and mRNA‐1273, in Germany. Methods A web‐based questionnaire was e‐mailed to all departments of neurology. We requested a report of cases of CVT occurring within 1 month of a COVID‐19 vaccination. Other cerebral events could also be reported. Incidence rates of CVT were calculated by using official statistics of 9 German states. Results A total of 45 CVT cases were reported. In addition, 9 primary ischemic strokes, 4 primary intracerebral hemorrhages, and 4 other neurological events were recorded. Of the CVT patients, 35 (77.8%) were female, and 36 (80.0%) were younger than 60 years. Fifty‐three events were observed after vaccination with ChAdOx1 (85.5%), 9 after BNT162b2 (14.5%) vaccination, and none after mRNA‐1273 vaccination. After 7,126,434 first vaccine doses, the incidence rate of CVT within 1 month from first dose administration was 0.55 (95% confidence interval [CI] = 0.38–0.78) per 100,000 person‐months (which corresponds to a risk of CVT within the first 31 days of 0.55 per 100,000 individuals) for all vaccines and 1.52 (95% CI = 1.00–2.21) for ChAdOx1 (after 2,320,535 ChAdOx1 first doses). The adjusted incidence rate ratio was 9.68 (95% CI = 3.46–34.98) for ChAdOx1 compared to mRNA‐based vaccines and 3.14 (95% CI = 1.22–10.65) for females compared to non‐females. In 26 of 45 patients with CVT (57.8%), VITT was graded highly probable. Interpretation Given an incidence of 0.02 to 0.15 per 100,000 person‐months for CVT in the general population, these findings point toward a higher risk for CVT after ChAdOx1 vaccination, especially for women. ANN NEUROL 2021