A 15-day shot for a dog bite may be effective, but it’s not an absolute, and the sooner you get vaccinated, the better, generally. Dog bites try to vaccinate within 24 hours, the sooner the injection of prevention, the better, has been bitten by a dog for 15 days, there is no morbidity can go to vaccination, may be effective, but not absolute. It takes some time after the injection of rabies vaccine to produce rabies antibodies, antibodies to a certain extent in order to produce a protective effect, at this time in the original basis and then delayed 15 days, the effect of treatment may be reduced, can not guarantee absolute effectiveness. Rabies immunoglobulin can be injected in advance so that the body can obtain rabies antibodies in time to be able to cover this period of vaccine interval. Rabies virus enters the body after a dog bite, and does not immediately enter the blood, the initial stage in the blood can not be detected rabies virus, the virus will be in the local tissues, into the muscle replication, reproduction, reproduction is more into the blood, triggered by rabies, the onset of the vaccine does not have a role in the vaccine. After being bitten by a dog, it is recommended to go to the hospital in time to deal with, do not keep delaying.