<unk>  was part of this response to a diphtheria epidemic, Berlin, 1962 When someone falls ill, people they might have infected should be vaccinated. Contacts who might have been infected typically include family, neighbours, and friends. Several layers of contacts may be vaccinated (the contacts, the contacts' contacts, the contact's contacts' contacts, etc.).<unk>  relies on contact tracing to determine possible infections. However, this can be difficult. In some cases, it is preferable to vaccinate as many people as possible within the geographic area of known infection (geographically-targeted reactive<unk> . If the infections occur within a defined geographic boundary, it may be preferable to vaccinate the entire community in which the illness has appeared, rather than explicitly tracing contacts. Many vaccines take several weeks to induce immunity, and thus do not provide immediate protection. However, even if some of the ill person's contacts are already infected,<unk>  can prevent the virus from being transmitted again, to the ill contacts' contacts. A few vaccines can protect even if they are given just after infection;<unk>  is somewhat more effective for vaccines providing this post-exposure prophylaxis.
Ring vaccination
Typhus vaccine
Polio vaccine
Typhoid vaccine
Rubella vaccine
Tetanus vaccine
Rabies vaccine
Measles vaccine