Case 1: On March 12, the FDA issued a safety warning for azithromycin and the risk of potentially fatal heart rhythms. This is based on a study published in 2012 in The New England Journal of Medicine as well as a manufacturer-sponsored study. Specifically, the FDA warns that azithromycin can lead to prolongation of the QT interval and possibly lead to Torsade de pointes. Patients at particular risk are those with existing QT prolongation, low serum potassium or magnesium levels, bradycardia, or who are taking certain anti-arrhythmic drugs. In such patients, alternative antimicrobials should be considered, although the other macrolides erythromycin and clarithromycin and the fluoroquinolones ciprofloxacin and levofloxacin also carry warnings for QT interval prolongation. MJ has no remarkable medical history and therefore should not be at increased risk of arrhythmias from her azithromycin regimen. She should take the medication as prescribed.
Case 2: The Advisory Committee on Immunization Practices recommends that all pregnant women receive the Tdap vaccination regardless of prior vaccination status. The optimal window for vaccination is between 27 and 36 weeks gestation in order to maximize the passive immunity transferred to the fetus. The peak immune response is observed 2 weeks after the vaccine is given. If the woman does not receive the Tdap during her pregnancy, the vaccine should be administered immediately postpartum, which is fully compatible with breastfeeding. There is also an advantage of the female herself being protected against pertussis to reduce the likelihood of transmission to the newborn. Of note, infants are not fully protected against pertussis until they are 6 months of age and have received their third DTaP vaccine. Ideally, SD should receive the Tdap now.