Keyword shout

1. Keyword shout • Shout a keyword from this topic • Pass the ball to someone • They have to give a definition - if correct then they can sit down after they have shouted their keyword • If a keyword is repeated – stay standing! • repeat again until only 1 person remaining

2. Immune system diseases Non specific immunity Disease survival mechanisms Physical & chemical barriers Infectious Disease Inflammatory Transmission Epidemiology Non-specific Cellular response Specific immunity Public Health Vaccination Immunological surveillance We are here T cells B cells Clonal Selection theory Big picture

3. Learning outcomes • examine the importance of vaccine uptake • state what is meant by herd immunity • describe the benefit of herd immunity to non-immune individuals • describe the importance of herd immunity in reducing the spread of disease • Provide evidence for potential problems in public health medicine

4. Herd Immunity • Only those with _____????______ have the ball – now pass it only to __________. • Everyone else try to intervene and prevent the ball reaching their target • How many times did the ball make its target?

5. Active Herd Immunity Group protection from a disease. If enough people are immunised, the disease is less likely to be transferred. The activity modelled this (ball, pathogen and the two people trying to pass were non-vaccinated) If one person is not immune they are still in effect protected. Eg. measles needs 92% of the population vaccinated to achieve active herd immunity.

6. Herd IMMUNITY • Complete this worksheet to illustrate what happens when immunisations in a population change • Why would the Uptake drop?

7. Members of a community who are not immune to a disease are still protected, provided sufficient numbers of people in that community are immune Little opportunity to spread and find a non-immune person Only applies to diseases that are caught from other people! Herd Immunity

9. Diphtheria vaccine • Before a vaccination programme was introduced in 1940, diphtheria was a very common condition and one of the leading causes of death in children. • The vaccination programme has been very successful. Since 1986, there have been only 15 recorded cases of diphtheria in England and Wales, and no deaths. Diphtheria is a notifiable disease, which means that if a doctor diagnoses the condition, they must tell the local authority. • Even though the incidence of diphtheria in England is low, there's a risk that an outbreak could occur if the number of people who are vaccinated falls below a certain level. • This risk was demonstrated by the diphtheria epidemic that struck the countries of the former Soviet Union between 1990 and 1998. It resulted in 157,000 cases and 5,000 deaths. The epidemic was caused by an increase in the number of children who were not vaccinated against the disease

10. Individual choice .... • Most people are well to have a vaccine • However some people in the community may be not eligible for the vaccine (cancer treatments or immunosuppressant) • The minor Non-immune people are protected by the majority of immunised people • This is the only prevention of disease we currently have – • When is a herd not a herd?

11. Herd immunity threshold • To be effective only a small minority can be unvaccinated • Percent depend on disease / virulence / transmission mode / population density and vaccine efficacy

12. Public health medicine • Immunization so effective it is still the main public health policy for combating disease • In the uk and other developed countries you have seen that vaccination uptake drops due to adverse publicity • In developing countries where high incidence of poverty and malnutrition large factors may not be a priority / cost • Who helps out – aim to eradicate polio – however 2012 8.8million children died of vaccine-preventable diseases!

13. Demonstration debate • Half the class; • One half will Agree with the statement (pro) • One half will disagree with the statement (opposition) • In your halves come up with arguments and counter arguments for your side – 8 minutes! • Nominate 4 people – 3 of who will deliver these arguments and the final person will summarise

14. Structure (1 minute each) class Vote • 1 argument from PRO side • 1 counter argument from OPPOSITION • 2nd argument from PRO side • 2nd counter argument from OPPOSITION • 3rd argument from PRO • 3rd counter argument from OPPOSITION • Final summary from PRO • Final summary from OPPOSITION Class Re-vote

15. Demonstration debate • Dr SohailBhatti, director of public health at NHS East Lancashire, proposes “to bar children who have not been vaccinated from school” • In America, where this is public policy, the incidence of childhood disease is lower than in this country. • Use examples from p337-338

16. review • What is herd immunity? • What causes the decrease in uptake of vaccines?

17. review

18. Summary Slide Herd immunity • If a large percentage of a population are immunised, non-immune individuals are protected as there is a lower probability that they will come into contact with infected individuals. • This herd immunity is important in reducing the spread of diseases and in protecting vulnerable and non-vaccinated individuals. • The herd immunity threshold depends on the disease, the efficacy of the vaccine and the contact parameters for the population.

19. Summary Slide Public health medicines • In most countries, policy in public health medicine is to establish herd immunity to a number of diseases. • Difficulties can arise when; • widespread vaccination is not possible due to malnutrition • widespread vaccination is not possible due to poverty (the developing world), • when vaccines are rejected by a percentage of the population (the developed world Eg. Mmr).