The following require the first doubling of the dose of rabies vaccine after a bite or scratch from a dog or cat, which means that the first of the five-dose method requires two injections, for a total of six injections: (1) persons who receive rabies vaccine 48 hours or more after the injury; (2) elderly persons; (3) patients with congenital or acquired immunodeficiency; (4) patients treated with immunosuppressive drugs, including anti-malarial drugs; and (5) chronically ill persons who have received rabies human immunoglobulin or rabies serum the day before or some time earlier than the rabies vaccination.