Risk profiles differed by experience, playing position, and surface types. We recommend future sports injury research that measures time-dependent exposures at the individual level and for various types of environmental playing conditions.

Background Sentiments of vaccine hesitancy and distrust in public health institutions have complicated the government-led COVID-19 vaccine control strategy in the United States. As the first to receive the vaccine, COVID-19 vaccine attitudes among front line workers are consequential for COVID-19 control and public opinion of the vaccine. Methods This study employed a repeated cross-sectional survey administered at three time points between September 24 – February 6, 2021 to a cohort of employees of University of California, Los Angeles (UCLA) Health and the Los Angeles County Fire Department (LACoFD). The primary outcome of interest was COVID-19 vaccination intent and vaccine uptake. Results Confidence in COVID-19 vaccines and vaccine uptake rose significantly over time. At Survey 1, confidence in vaccine protection was 46.4% among healthcare workers (HCW) and 34.6% among first responders (FR); by Survey 3, this had risen to 90.0% and 75.7%, respectively. At Survey 1, about one-third of participants intended to receive a vaccine as soon as possible. By Survey 3, 96.0% of HCW and 87.5% of FR had received a COVID-19 vaccine. Conclusions Attitudes towards vaccine uptake increased over the study period, likely a result of increased public confidence in COVID-19 vaccines, targeted communications, a COVID-19 winter surge in LA County, and ease of access from employer-sponsored vaccine distribution.

This adapted sports program is a reasonably safe activity for children with disabilities. Nonetheless, findings have important implications for prevention. The preparticipation medical examination may be an excellent opportunity to create special guidelines, particularly for athletes with autism and seizure history.

Footnotes: * "Not contacted" refers to the 108 patients who were treated and released and either did not provide a contact phone number and/or did not answer their phone on multiple attempts ** "Contacted but not surveyed" refers to the 18 patients successfully contacted by telephone but who did not agree to complete the phone survey

Two mRNA vaccines (BNT162b2 and mRNA-1273) against severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) are globally authorized as a two-dose regimen. Understanding the magnitude and duration of protective immune responses is vital to curbing the pandemic. We enrolled 461 high-risk health services workers at the University of California, Los Angeles (UCLA) and first responders in the Los Angeles County Fire Department (LACoFD) to assess the humoral responses in previously infected (PI) and infection naïve (NPI) individuals to mRNA-based vaccines (BNT162b2/Pfizer- BioNTech or mRNA-1273/Moderna). A chemiluminescent microparticle immunoassay was used to detect antibodies against SARS-CoV-2 Spike in vaccinees prior to (n = 21) and following each vaccine dose (n = 246 following dose 1 and n = 315 following dose 2), and at days 31–60 (n = 110) and 61–90 (n = 190) following completion of the 2-dose series. Both vaccines induced robust antibody responses in all immunocompetent individuals. Previously infected individuals achieved higher median peak titers (p = 0.002) and had a slower rate of decay (p = 0.047) than infection-naïve individuals. mRNA-1273 vaccinated infection-naïve individuals demonstrated modestly higher titers following each dose (p = 0.005 and p = 0.029, respectively) and slower rates of antibody decay (p = 0.003) than those who received BNT162b2. A subset of previously infected individuals (25%) required both doses in order to reach peak antibody titers. The biologic significance of the differences between previously infected individuals and between the mRNA-1273 and BNT162b2 vaccines remains uncertain, but may have important implications for booster strategies.