In 2015, Brazil faced a Zika virus epidemic that spread to other countries in the world. As a result, recommendations regarding reporting criteria for congenital Zika syndrome (CZS) were issued in the form of protocols. The frequent changes in these recommendations may have affected clinical management and the access to post-diagnostic support by children who were affected by CZS, but who ended up not being identified. In the present study, 39 cases of CZS reported in the state of Espírito Santo, Brazil, from 2015 to 2016 were re-classified in terms of diagnosis using the current protocol, which is different from the protocol used in 2015. According to this re-classification, only eight out of 36 cases would be confirmed, based on the criterion of two or more signs or symptoms of CZS with or without microcephaly plus positive serologic results. Also, considering the decrease in the head circumference cut-off point defining microcephaly, 17 cases would no longer meet the definition for this condition. Even though the current protocol does not rely on head circumference alone for CZS reporting and confirmation, it should be noted that this is still the main sign considered by health care teams, and therefore the decrease in the cut-off point might have compromised early CZS detection. A review of “ruled out” cases would be advisable in moments of protocol transition to determine whether these cases have been correctly classified
