Are Economics Students Biased Against Female Teachers? Evidence from a Randomized, Double-Blind Natural Field Experiment (preprint)

Previous research suggests that student evaluations of teacher performance are biased against women. We test this hypothesis on economics students in a randomized, double-blind experiment, set up in a natural educational setting. During the Covid-19 pandemic, teaching assistants moved online and answered questions through email instead of on-campus group sessions. We randomly assigned a male or female name to the instructions given by the online teachers. Importantly, the teachers actually responding to the questions did not know whether they interacted with the students as male or female, which is a novel contribution to the literature. The course evaluation asked students to rate the mentors' helpfulness, knowledge, and response time. The results show no bias against the female mentor in any single dimension. Our confidence interval around the zero effect does not overlap the effect sizes reported in highly influential previous studies.

Anticipation of COVID-19 Vaccines Reduces Social Distancing (preprint)

We show that the anticipation of COVID-19 vaccines reduces voluntary social distancing. In a large-scale preregistered survey experiment with a representative sample, we study whether providing information about the safety, effectiveness, and availability of COVID- 19 vaccines affects compliance with public health guidelines. We find that vaccine information reduces peoples’ voluntary social distancing, adherence to hygiene guidelines, and their willingness to stay at home. Vaccine information induces people to believe in a swifter return to normal life and puts their vigilance at ease. The results indicate an important behavioral drawback of the successful vaccine development: An increased focus on vaccines can lead to bad health behaviors and accelerate the spread of the virus. The results imply that, as vaccinations start and the end of the pandemic feels closer, existing policies aimed at increasing social distancing will be less effective and stricter policies might be required.

Intrauterine SARS-CoV-2 infection – a case confirming transplacental transmission followed by divergence of the viral genome (preprint)

Pregnant women and their newborns may be at particular risk for poor outcomes due to the coronavirus (COVID-19) pandemic. Intrauterine SARS-CoV-2 transmission has been suggested but most reports have not ruled out postpartum infection. We demonstrate a confirmed case of transplacental transmission of SARS-CoV-2 in a neonate born to a mother infected in the third trimester. Comprehensive virological, pathological and genetic investigations establish that intrauterine SARS-CoV-2 transmission occurred via the following chain of events; I) maternal viremia in a seemingly mildly symptomatic patient, II) high viral load in the placenta with massive perivillous fibrin deposition, acute intervillositis in areas with strong positivity for SARS-CoV-2 and chorangiosis in the areas less affected by infection and inflammation, III) intrauterine fetal distress with pathological cardiotocography and acidemia in validated umbilical cord blood gases and IV) mild neonatal COVID-19. Whole genome sequencing of isolates from the mother and placenta revealed a single variant of the virus. Interestingly, the neonate displayed a mixed SARS-CoV-2 population, harboring both an identical strain to the mother as well as a population with one single-nucleotide polymorphism difference, indicating intrapatient genetic drift.