Our Vaccines411 glossary provides quick and easy access to certain scientific and technical terms featured throughout the website.
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Birth defects (also known as congenital anomalies) can be defined as structural or functional abnormalities that occur to foetuses in the womb and can be detected prenatally, at birth, or sometimes may only be diagnosed later in life. Birth defects can contribute to long term mental and/or physical disabilities as well as chronic illness and death.
Although approximately 50% of all birth defects cannot be linked to a specific cause, there are some known genetic, environmental and other causes or risk factors. Some birth defects can be prevented. Vaccination, adequate intake of folic acid or iodine through fortification of staple foods or supplementation, and adequate antenatal care are just 3 examples of prevention methods.25
Ebola virus disease (EVD), formerly known as Ebola haemorrhagic fever, is a severe, often fatal illness in humans.
The virus is transmitted to people from wild animals and spreads in the human population through human-to-human transmission via direct contact (through broken skin or mucous membranes) with the blood, secretions, organs or other bodily fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids.
Humans are not infectious until they develop symptoms. First symptoms are the sudden onset of fever fatigue, muscle pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, symptoms of impaired kidney and liver function, and in some cases, both internal and external bleeding (e.g. oozing from the gums, blood in the stools).
There are currently no licensed Ebola vaccines but 2 potential candidates are undergoing evaluation.23
Poliomyelitis (polio) is a highly infectious viral disease, which mainly affects young children. The virus is transmitted by person-to-person spread mainly through the faecal-oral route or, less frequently, by a common vehicle (e.g. contaminated water or food) and multiplies in the intestine, from where it can invade the nervous system and can cause paralysis.
Initial symptoms of polio include fever, fatigue, headache, vomiting, stiffness in the neck, and pain in the limbs. In a small proportion of cases, the disease causes paralysis, which is often permanent. There is no cure for polio, it can only be prevented by immunization.22
A lack of availability of a certain vaccine which can occur due to: the company that manufactures it not being able to produce the vaccine fast enough to meet the demand, a company seizing to manufacture a vaccine for business reasons, a vaccine supplier not being able to send out the vaccine quickly enough, a contamination in the lab where the vaccine is manufactured, a outbreak of the illness resulting in too high of a demand, etc.
Typically the vaccine supply is not completely wiped out, but there are fewer doses than usual. During this time, doctors give vaccines first to the people who need them most. This list may include the elderly, very young children, pregnant women, people who have certain medical problems, and people who plan to travel to other countries. Other people are put on a waiting list. A shortage may last a few days to several months.27
Note: the hyperlinks that direct to other sites are not continuously updated. It is possible that some links become untraceable over time. Thank you.Last Updated: February 27, 2023