The Food and Drug Administration (FDA) has asked Pfizer to conduct a safety study of the Respiratory Syncytial Virus Infection (RSV) vaccine if approved this spring. The agency sees it as a risk for Guillain-Barre syndrome in older adults because two 60 year-olds were diagnosed with Guillain-Barre syndrome, a rare auto-immune disorder where the immune system mistakenly attacks the nerves, during the phase three trial. Pfizer said that they will conduct a safety study if the vaccination is completely approved. “Given the temporal association and biological plausibility, FDA agrees with the assessments of the investigators that these events were possibly related to study vaccine” the FDA stated.