A team of CDC analysts studied the effect of thimerosal exposure on infants starting in 1999 using data from the Vaccine Safety Datalink (VSD). They published their first results for an Epidemic Intelligence Service (EIS) Conference that was internal to the CDC. These results included a significant finding that the highest exposure group of one-month-old infants had a 7.6 times higher risk of autism than the zero-exposure group. Later generations of this analysis changed the methodology in ways that obscured this finding.