What about the Yankees’ rate of spread? Is nine infections out of 50 to 60 people high? To fully answer that question, we would need to know how many would have become infected without the vaccine, which would require a detailed epidemiological investigation of contact patterns within the team. But we can look at similar outbreaks to assess the risk in unvaccinated teams. Last July, 18 players and two coaches on the Miami Marlins tested positive. Shortly after, the St. Louis Cardinals saw its own outbreak among 18 people (10 players and eight staff). These would have represented at least 30 to 40 percent of a typical traveling party in 2020. In the National Football League, the Tennessee Titans had 24 cases (13 players, 11 staff) in October, while the Baltimore Ravens had more than 12 cases in December. These both represented about 20 percent of players; the percentages for staff are more difficult to estimate. All of these outbreaks occurred under tighter covid-19 protocols than what the Yankees were under, including greatly limited shared indoor time and strict masking requirements. Vaccinated Yankees were allowed to spend unmasked time together indoors in hotels and clubhouses. Coaches and staff, who represent eight of the nine cases, were in tight indoor quarters during a rain delay just before the outbreak began. This is a perfect environment for the virus to spread, much like the Skagit County, Washington, choir practice outbreak in March 2020 that sickened about 86 percent of the 61 attendees.