US Centers for Disease Control and Prevention (CDC) has confirmed that 47 people had tested positive for coronavirus in an Oklahoma gymnastics facility over a two-week period in April and May of this year. The outbreak had exposed a total of 194 people, according to CDC’s Morbidity and Mortality Weekly Report that was released on Friday.

The infected people at the facility included 21 gymnasts, along with 3 staff members and 21 household contacts, who caught “secondary cases” of COVID-19 from the initial outbreak.

CDC sequenced a total of 21 of the 47 cases caught during the outbreak and all the samples sequenced were identified as the more transmissible Delta variant, CNN reported.

An investigation was launched to find the potential risk factors at the facility that may have contributed to the outbreak.  According to the investigation, the factors include a failure to follow recommended quarantine and testing guidelines, failure to recognise symptomatic cases in the camp, inconsistency in the use of mask, poor ventilation, low rate of vaccination. Apart from that, several groups of athletes were training at the same time at the facility, and the cleaning of frequently touched surfaces was also inadequate. Same staff members were being used to treat multiple groups of athletes, spiking the chances of infection.

Only four of the gymnasts who tested positive were fully vaccinated and were all of them mildly symptomatic. Three gymnasts were partially vaccinated. All the remaining 40 cases were in people who did not get even one dose of the COVID-19 vaccine. Two people, who had to be hospitalised, were from the unvaccinated group of people. One of them ended up requiring intensive care.

27 infected people, including one 5-year-old, were not eligible for getting a COVID-19 vaccine at the time of the outbreak.

The on-site testing and vaccination facility that was offered after the outbreak led to the vaccination of 9 more people from the facility.