List down the first name of patients who received "Influenza seasonal injectable preservative free" immunization.
"Influenza seasonal injectable preservative free" immunization refers to immunizations where DESCRIPTION = 'Influenza seasonal injectable preservative free';
SELECT DISTINCT T1.first, T1.last FROM patients AS T1 INNER JOIN immunizations AS T2 ON T1.patient = T2.PATIENT WHERE T2.DESCRIPTION = 'Influenza  seasonal  injectable  preservative free'