Lec 6- Vaccine systems Flashcards
1
Q
Vaccines and public health
A
- The two public health interventions that have had the greatest impact on the worlds health are clean water and vaccines
2
Q
AIM of vaccines
A
- To exploit the natural defence mechanism of a body immune system to promote long term immunological protection against the establishment of an infection
- I.e.- an appropriate and effective immune response
3
Q
Eradication of smallpox
A
- 1796, Edward Jenner, an english doctor discovered the first successful smallpox vaccination
- 1980, as a result of Jenner’s discovery, the world health assembly officially declared
4
Q
1967: WHO global campaign to eradicate smallpox
A
- The USSR first suggested a global effort and donated 80% of vaccines
- A freeze-dried vaccine employed
- Storable without refrigeration
- 1-month stability
- This was delivered with a bifurcated needle
- Low dose and could be sterilized
5
Q
Mechanism of vaccination: principle of specific immunity
A
- Secondary response there shouldn’t be symptoms of the disease
- Watch evolution of vaccines again
6
Q
Vaccine Failures
A
- Malaria
- 225 million cases per year
- Nearly 1 million deaths a year
- HIV
- 25 million deaths
- 33 million people living with HIV
- 2.6 cases every year
- 1.8 million deaths per year
- TB
- 9.6 million new cases a year
- 1.7 million deaths yearly
7
Q
HIV, TB and malaria- ongoing challenges
A
- Historically successful vaccines have been developed mostly against those pathogens that
- Can be treated by antibodies
- And have a stable antigen
8
Q
Recent advance in malaria vaccine
A
- RTS, S/AS01 malaria vaccine
- Developed through a partnership between GSK and MVI (malaria vaccine initiative) with support from Bill & Melinda Gates Foundation and from a network of African research centres that performed the studies
- RTS, S the first malaria vaccine to have completed pivotal Phase 3 testing and obtained a positive scientific opinion by a stringent medicines regulatory authority
- RTS, S is a vaccine against P.falciparum, the most deadly malaria parasite globally, and the most prevalent in Africa (it offers no protection against P.vivax malaria)
9
Q
Recent advance in malaria vaccine
A
- There were two target age groups in the trial.
- Infants who received the malaria vaccine together with other routine childhood vaccines at 6, 10 and 14 weeks of age.
- Older children who received their first dose of the malaria vaccine between 5 and 17 months of age.
- Over the full duration of the trial, efficacy against clinical malaria in infants was 27% in the group that received four doses of RTS,S (3 doses at 6, 10 and 14 weeks of age, and a fourth dose 18 months later); and 18% in the group that did not receive the fourth dose of the vaccine.
- Among children aged 5-17 months who received four doses on a 0, 1, 2, 20-month schedule, vaccine efficacy against clinical malaria was 39% over the full duration of the trial. With a four-dose schedule, the overall efficacy against severe malaria among children in this age group was 31.5%. In children aged 5-17 months who did not receive a fourth dose of the vaccine, no protection was seen against severe malaria, These results highlight the importance of the fourth dose with this vaccine, as efficacy is short-lived
10
Q
Herd immunity
A
11
Q
Risk-benefit
A
- The implementation of vaccines programmes depends on their perception in an environment of risk and benefit
- I.e. adverse effects vs perception of the disease
- In a climate of low risk of associated disease- concerns over vaccine safety intensify e.g. MMR
12
Q
Examples of adverse responses
A
- Live attenuated viral vaccines
- Simple headache to encephalitis (MMR)
- Intussception (Rotavirus)
- Vaccine associated disease (Polio)
- Inactivated vaccines
- Nausea to anaphylactic reactions and neurological complications (extremely rare)
13
Q
Highest MMR vaccine coverage in 25 years
A
- The health and social care information centre (HSCIC) reported that from 2012 to 2013, 92.3% of children reaching their second birthday received MMR vaccination
- This is the highest recorded level since the vaccine was first introduced in 1988
- The latest MMR coverage figure also shows considerable improvement from the lowest recorded figure of 79.9% which occurred 03-04
14
Q
Requirements of vaccines
A
- Safe
- Effective
- Induce the right sort of immunity-
- Affordable
- Avoid needles
- Avoid cold chain- refrigerated transport- makes transport harder due to stability
15
Q
Classes of vaccine
A
- Live attenuated
- Bacille Calmette Guerin of a M.Bovis close to Mycobacterium TB
- Inactivated
- IPV- virus is killed via chemical treatment
- Extracts
- Hep B surface Ag. Grown in culture
16
Q
1) Live, attenuated, vaccines
A
- Attenuation: the process of elimination or greatly reducing the virulence
- Using e.g. Heat, chemical treatment, enzymatic treatment, genetic modification
- E.g. BCG is a strain of M.Bovis that fails to cause TB but retains much of the antigenicity of the pathogen
- Can’t rule out microbe reverting back
