Term
| Definition of incubation period, infectious period, latent period |
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Definition
- Incubation/latent period - the period of time between exposure to infection and appearance of symptoms
- Infectious period - time period during which theose infected is able to transmit infection to susceptible host or vector
- Latent period - the period of time between exposure and infectionÂ
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Term
| Definition of epidemic, outbreak and pandemic |
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Definition
- Epidemic is widespread occurance of infectious disease in a community at a particular time
- An outbreak is a sudden increase of cases of a particular disease in a certain area at the same time (but not to the level of an epidemic)
- Pandemic is a spread of a disease across a large region of human population
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Term
| Attack rate and secondary attack rate meaning |
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Definition
- Attack rate is a biostatistical measure of the frequency of morbidity (speed of spread) in an at risk population
- Secondary attack rate is the probability that infection occurs among susceptible persons within a reasonable incubation period following known contact with infectious person or source
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Term
| Study types in epidemiology |
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Definition
- Case control study - retrospectively assesses whether historical exposure to risk factor in people who have the disease is comparible to people who do not have the disease
- Cohort - prospective study of subjects divided into groups dependent on whether they have or haven't been exposed to a risk factor, which the proportion of those with the disease studied at a set end point
- Randomised control trial - study where the efficacy of a intervention is calculated by comparing outcome with placebo with that of the intervention.
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Term
Phases of clinical trialsÂ
(main goal and methods) |
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Definition
- Phase I - checking for safety, use 10-20 healthy volunteers and looking for side effects
- Phase II - checking for efficacy, use around 200 patients and efficacy calculated
- Phase III - confirmation of Phase II results in >1000 patients
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Term
| Definition of vaccine efficacy, herd immunity, basic reproduction number and critical vaccination percentage |
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Definition
- Vaccine efficacy - percentage reduction of disease in vaccinated group compared to unvaccinated group
- Herd immunity - the indirect protection of infectious disease that occurs in a population with a large percentage of vaccinated individuals
- Basic reproduction number - the number of cases of infection one case of infection generates over the course of its infectious period
- Critical immunisation threshold is the level at which one infected individual infects less than one other, thus inducing herd immunity and interrupting endemic transmission
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