Clinical and public health aspects of immunisations Flashcards

1
Q

What is the role of WHO in the global public health importance of immunisation? What programmes have been set to address this?

A

WHO/expanded programme of Immunisation (EPI): concentrate on children in low income countries

EPI (1974) focused on the big 6 infectious diseases

EPI (2019): addition of MMR, HepB, HiB (Haemophilus influenza B), pneumococcal, rotavirus, HPV vaccines to programme

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2
Q

What were considered the big 6 infectious diseases (now terms vaccine preventable illness)?

A
VPI: vaccine-preventable illness
Big 6:
- pertussis (whooping cough)
- diphtheria 
- Tetanus 
- Poliomyelitis 
- Mumps
- Measles
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3
Q

Which immunisations were added to the the Big 6 in 2019?

A
MMR
HepB
HiB (h. influenza B)
Pneumococcal 
Rotavirus 
HPV
(TB/BCG is only given to high risk groups, currently)
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4
Q

Which vaccines are not in progress or only given to a certain individuals?

A

Malaria - first vaccine to protect children is currently being piloted in sub-Saharan Africa

TB: used to be part of the national immunisation schedule 
But now (2019), BCG is only offered to high risk individuals because the population prevalence is so low
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5
Q

What are the main public health importance of immunisation?

A

addressing the top infectious causes of disease and associated morbidities globally and nationally

By reducing the prevalence of these (often bacterial infections), this has a benefit on reducing Abx resistance (which is another major public health issue)

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6
Q

What is the vaccine hesitancy cycle?

A

Vicious cycle of public perception of vaccine effectiveness whereby society travels through the following stages:

  • campaigns promote vaccines
  • increased vaccine uptake
  • herd immunity achieved/maintained
  • decreased incidence of VPIs means that it is seen less and so society is less fearful
  • Vaccines for these less frequently occurring VPIs = perceived to be unimportant
  • More concern placed on vaccine safety
  • reduced vaccine uptake
  • re-emergency of VDIs
  • need for campaigns to promote vaccines

this cycle repeats through time

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7
Q

Which of the big 6 has been recently seen in epidemics globally? What can impact whether there is re-emergence of disease caused by poor vaccine uptake?

A

Polio(myelitis)
Outbreaks in Syria and Iraq
Vaccine schedule and uptake is highly impacted by political views and as this is a very fluid environment, this can change quickly before the impact of vaccines has even taken effect

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8
Q

Why is tetanus unlikely to ever be eradicated completely?

A

Spores that cause tetanus are found in the soil
(naturally occurring)
Therefore difficult to eradicate

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9
Q

How infectious is measles?

A

for 100 susceptible people (not vaccinated), intro of 1 infected person will result in 90% becoming infected. 7 of these 90% (i.e. 7 out of 90 people) will have associated complications

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10
Q

What is herd immunity?

A

the level of immunity in a population against a specific disease?

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11
Q

How are vaccination rates and herd immunity levels related?

A

Vaccination rates are PROPORTIONAL to herd immunity levels

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12
Q

What is the benefit of herd immunity?

A

adequate: necessary to prevent outbreaks of infectious disease
high: also protects vulnerable or unprotected groups

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13
Q

What is the trend of whooping cough incidence and vaccination rates?

A

1960s: immunisation introduced
rapid decrease in prevalence until 1980
1980: Dip in vaccine uptake results in 2 major outbreaks and relative increase in prevalence

2011-2012: Confirmed whooping cases have taken a sharp rise

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14
Q

Where have the recent new cases for pertussis come from? In which childhood sub-group, is there greatest risk for whooping cough infection?
What is the solution?

A

New cases = newborn babies and those infants part of the way through a vaccination programme

Solution: immunisation for pertussis to pregnant women (1 vaccination per pregnancy)
Implemented: 2012 onwards (given at 20-32 weeks)
This provides passive immunity to baby for first few months of life until baby can generate its own active immunity to pertussis Ag

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15
Q

The UK Childhood immunisation schedule is complex. What are the main illnesses covered by it?

A
  • Diptheria
  • Tetanus
  • acellular pertussis
  • inactivated polio vaccine
  • Haemophilus influenzae B
  • Hep B
  • Pneumococcal conjugate vaccine (13 serotypes)
  • Meningococcal B
  • Rotavirus
  • MMR
  • Live attenuated influenza
  • HPV
  • Meningococcal ACWY conjugate
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16
Q

What age does childhood immunisation schedule run? Where does it take place?

A

Primary Care: starts @ 2 months old - ends 3 years 4 months

School: starts 12-13 yr old - ends 14 year olds

17
Q

Which of the childhood immunisation vaccines contain live (attenuated) material?

A
  • oral rotavirus
  • MMR
  • Nasal flu vaccine (LAIV)

Generally given by the oral/nasal route

18
Q

What are the immunisations given to risk groups?

A

Hep B infected mothers
- at birth, 1mo, 12mo (HepB and hexavalent vaccine)

Endemic TB prevalence/parent+gparent born in endemic nation

  • given at birth
  • vaccine: BCG

Chronic medical condition

  • Flu: given annually (6 months to 2 years, over 6 years to <18)
  • Pneumococcal (PPV, 23 serotypes): over 2 years
19
Q

What is the controversy with the MMR vaccine?

A

Case started in Lancet 1998 reporting link between MMR vaccine and autism
12 cases reported
hypothesis is that vaccine allows for the gut absorption of normally non-permeable peptides leading to developmental disorders

20
Q

What was the main criticism of the MMR Lancet research?

A
  • temporal association with MMR (likely to due to chance)
  • selection bias
  • not replicable
  • post-marketing surveillance and reviews confirm vaccine safety
  • epidemiological evidence supports safety
  • conflict of interest/unethical behaviour (Wakefield struck off)
  • Data shown to be fraudulent (Deer BMJ, 2011)
21
Q

What is the current WHO recommendation for MMR?

A

WHO + leading health professionals groups recommend immunisation with MMR

22
Q

What vaccination coverage is needed to ensure herd immunity for measles? Why is this?

A

96%
Measles is very contagious so coverage need to be HIGH to ensure this.

current estimates put coverage at 90%

23
Q

Are anti-vaccination protests new?

A

No, Victorian cartoons depict similar views WRT cowpox/smallpox vaccinations

24
Q

What are the 3 main high risk groups for who immunisation is critical?

A
  • travelling to high risk areas
  • occupational groups (where exposure is potentially higher)
  • patients with immunodeficiency
25
Q

What are the main things to consider with immunisation for travel abroad?

A
  • deficiency with completing primary courses for immunisation
  • Europe, N. America, Japan, Australia and New Zealand: no further immunisation needed
  • Typhoid and Hep A: for other areas
  • consider HepB for high aero-prevalence areas
26
Q

For which countries, do you need a yellow fever certificate for entry?

A

= confirmation of immunisation record

S. America, Sub-Saharan Africa

27
Q

Which immunisations are considered only for special circumstances?

A
  • Japanese encephalitis: for SE east and Far East endemic rural areas at monsoon season
  • Rabies: need pre-exposure immunisation for long journeys in remote and enzootic areas
  • Tick borne encephalitis for forested areas in E. Europe
  • Meningitis ACWY: Hajj and Umra pilgrimage
28
Q

What do occupational groups and safety workers need protection against?

A
  • Hep B
  • All health workers should be immune to rubella, TB and chicken pox (varicella)
  • Rabies prophylaxis for lab workers handling rabies virus/imported animals
29
Q

What are the different types of immunodeficiency?

A

Primary: born with it e.g. congenital source, often genetic

Secondary: Acquired immunodeficiency e.g. leukaemia, HIV or from Rx (steroids, chemo, methotrexate)

30
Q

Why is immunisation particularly important for immunodeficient patients?

A
  • they are particularly susceptible to many infections
  • may not be able to mount a NORMAL immune responses to live vaccines (therefore these are generally not considered to be safe)
    However, inactivated vaccines are assumed to have reduced efficacy
31
Q

What are the immunisation considerations for patients with hyposplenism?

A
  • splenic dysfunction e.g. sickle cell or coeliac
  • loss of spleen (e.g. congenital or trauma)
  • increased risk for bacterial infections especially encapsulated organisms
  • Recommended vaccines: PPV, HiB, Influenza, MenACWY, MenB
32
Q

Which groups are influenza vaccines given to in addition to chronic illness?

A
  • pregnant women
  • long stay patients
  • health care workers
  • long term carers
  • 2-6 yo nasal flu vaccine
33
Q

Which groups are pneumococcal vaccines given to in addition to chronic illness?

A
  • cochlear implant and CSF shunt
34
Q

What is the Herpes Zoster/Shingles vaccine?

A

incidence dramatically increases after 50 yo
severity increases with age too
(1% mortality) for people in 70s)
vaccine given to 70yo
live vaccine - can’t give to immunocompromised

35
Q

What are the main contraindications to immunisation?

A
  1. Acute illness - does not include minor infections w/o systemic involvement e.g. afebrile means fine to go ahead
  2. Live vaccines: not to be given to immunocompromised and in pregnancy
  3. Anaphylactic reaction to previous dose
  4. Specific contraindications: e.g. egg hypersensitivity for influenza vaccine
36
Q

What are the main ethical issues regarding immunisation?

A
  • balancing public needs against an individual’s right to refuse vaccination
  • importance of informed consent
  • ways of increasing vaccination uptake (education or legal compulsion)
  • GP payments for reaching immunisation targets
  • ethical issues raised by MMR scandal
  • ethical issues by vaccinating girls only for HPV (now also boys)
  • ethical issues if vaccine stocks are low
37
Q

Which vaccines are live attenuated preparations?

A
  • BCG
  • MMR
  • influenza (intranasal)
  • oral rotavirus
  • oral polio
  • yellow fever
  • oral typhoid
38
Q

Which vaccines are inactivated preparations?

A
  • rabies
  • hep A
  • influenza (IM)
39
Q

Which vaccines are inactivated toxin preparations?

A

= toxoid vaccinations

  • tetanus
  • diphtheria
  • pertussis