The expiration date of rabies vaccine is a controversial topic. For example, in 2009, our country launched a rabies prevention and control regulations, where it is recommended that after the full vaccination of rabies, if the exposure occurs again within six months, you are said to have been bitten by a dog, 5 doses of vaccine or 4 doses of vaccine, in accordance with the requirements of the full course of treatment, within six months you were bitten by a dog, cat scratched. This half year is not necessary to vaccinate again, because it is believed that the rabies protection period, the vaccine protection period of six months is no problem, more than six months may not be 100 percent effective. Then in 2016, the Chinese Center for Disease Control and Prevention (CDC) reissued a guide for the prevention and control of rabies. In this guideline it is recommended that if it is within three months, you can not vaccinate, more than three months to consider a booster vaccine, and within three months of re-exposure, or to see if the animal can be observed, if it can be observed for ten days. If the animal can be observed for ten days, the vaccine can be withheld. If the exposure cannot be observed or is more serious, such as a serious bite, the vaccine should be boosted. That is, one rabies vaccine on day 0 and another on day 3. At the same time, the 2016 guidelines state that the 2009 rabies prevention and control regulations can still be used as a reference, which leaves many clinicians conflicted, so for 3-6 months re-exposure or not, this is a controversial topic. My personal opinion is that if we have finished the vaccination and the exposure occurs again within 3-6 months, the health of the animal must be evaluated. If the animal’s health is relatively assured, for example, if the animal has been vaccinated, or if it is a domesticated animal in the city, then you can start without a booster shot, and if the animal is less reliable, for example, if it is a stray animal, then you must go for a two shot booster.