According to The Detroit News, 246 “breakthrough cases” were reported between Jan. 1 and March 31. All cases occurred in people who tested positive 14 or more days after the last dose in the vaccine series, said Lynn Sutfin, spokeswoman for the Michigan Department of Health and Human Services, in an email.

“Some of these individuals may ultimately be excluded from this list due to continuing to test positive from a recent infection prior to being fully vaccinated,” she said. But these “cases are undergoing further review to determine if they meet other [Centers for Disease Control and Prevention] CDC criteria for determination of potential breakthrough, including the absence of a positive antigen or PCR test less than 45 days prior to the post-vaccination positive test.”

Sutfin said these persons were more likely to be asymptomatic or mildly symptomatic, adding that hospitalization data were available for 117 of the cases, while 129 were incomplete.

Of the 117 with hospitalization data entered, 11 were hospitalized, 103 were not hospitalized and three are reported as unknown. The three people who died were all 65 or older and two “were within three weeks of completion of vaccination,” Sutfin said.