<unk> s are vaccines that are effective at preventing<unk> . For the first six months after vaccination they provide about 85percent protection, which decreases to 50percent or 62percent during the first year. After two years the level of protection decreases to less than 50percent. When enough of the population is immunized, it may protect those who have not been immunized (known as herd immunity). The World Health Organization (WHO) recommends the use of<unk> s in combination with other measures among those at high risk. With the oral vaccine, two or three doses are typically recommended. The duration of protection is two years in adults and six months in children aged 2–5 years. A single dose vaccine is available for those traveling to an area where<unk>  is common. In 2010, in some countries an injectable<unk>  was available. The available types of oral vaccine are generally safe. Mild abdominal pain or diarrhea may occur. They are safe in pregnancy and in those with poor immune function. They are licensed for use in more than 60 countries. In countries where the disease is common, the vaccine appears to be cost effective. The first vaccines used against<unk>  were developed in the late 1800s. They were the first widely used vaccine that was made in a laboratory. Oral vaccines were first introduced in the 1990s. It is on the World Health Organization's List of Essential Medicines.
Cholera vaccine
Hookworm vaccine
Malaria vaccine
Schistosomiasis vaccine
Brucellosis vaccine
Rabies vaccine
Ebola vaccine
Dengue vaccine