I also found some other ads campaigns that were taken the same approach as the AT & T ads campaign, such as Kimberly-Clark Professional and Secretaria Estadual Da Saúde. By comparing the details of the hands paintings, I do believe these two ads campaigns were done by other artists.

Kimberly-Clark Professional Ads campaign—Do you know what you wash your hands with

Secretaria Estadual Da Saúde ads Campaign—Your hands can be dangerous. Wash hands with soap with water to ensure that bacteria will not follow you