Teamwork is an essential component of patient safety.  This cross-sectional study of 50,000 healthcare workers in four large US health systems found that the teamwork climate worsened during the COVID-19 pandemic. Survey findings indicate that healthcare facilities with worsening teamwork climate had corresponding decreases in other measured domains, including safety climate and healthcare worker well-being. The researchers suggest that healthcare organizations should proactively increase team-based training to reduce patient harm.