Breakthrough COVID infections after vaccination are quite rare, which is why the cases that have occurred have garnered so much attention. Experts are working to identify the common threads among breakthrough infections so that we can better understand them. Recently, eight members of the New York Yankees who were fully vaccinated tested positive for COVID, and all eight have one notable thing in common: They aren’t severely ill, and only one has any symptoms at all.RELATED: The CDC Says People Who Get COVID After Vaccination Have This in Common.A statement released by the Yankees on May 13 said that eight members of the team, including a Yankees player, coaches, and traveling staff members, have tested positive for COVID in the past week. “All of the positives are breakthrough positives, occurring with individuals who were fully vaccinated,” according to the statement, which means these people were vaccinated more than two weeks ago. The infected members don’t have any severe symptoms, and seven are asymptomatic, Jason Zillo, the team’s vice president of communications, told CNN. Only third base coach Phil Nevin experienced any symptoms, but he is feeling better now, Zillo said.CNN reports that these Yankees all received the Johnson&Johnson vaccine. The single-dose vaccine is 72 percent effective at preventing COVID infections in the U.S. and 85 percent effective at preventing severe COVID cases, per a statement from Johnson&Johnson. According to CNN, the Yankees have been playing under relaxed health and safety protocols since late April when they reached the Major League Baseball-recommended 85 percent threshold of vaccinated team members.Vaccinated people can get breakthrough infections, although the occurrence is rare. The CDC previously told Best Life that 5,800 breakthrough infections had been reported as of April 13. With over 75 million people fully vaccinated in the U.S. as of that date, these 5,800 cases represent only 0.008 percent of the vaccinated population. RELATED: For more up-to-date information, sign up for our daily newsletter. During a May 13 White House COVID-19 Response Team press briefing, someone inquired about the Yankee breakthrough infections. “We obviously need to learn more about that situation,” CDC Director Rochelle Walensky, MD, said. “All of the real-world data that we’ve seen that’s been in the published literature, large studies in many different settings have demonstrated that the vaccines are effective.”The CDC was upfront about the potential for breakthrough infections early on. However, the agency notes that the majority of people who have a breakthrough infection manage to evade severe symptoms. “Even though a small percentage of fully vaccinated people will get sick, vaccination will protect most people from getting sick,” the CDC says. “There also is some evidence that vaccination may make illness less severe in people who get vaccinated but still get sick.”RELATED: 65 Percent of Vaccinated People Who Get COVID Have This in Common, CDC Says.