Clinical and public health aspects of immunisations Flashcards
What is the role of WHO in the global public health importance of immunisation? What programmes have been set to address this?
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
What were considered the big 6 infectious diseases (now terms vaccine preventable illness)?
VPI: vaccine-preventable illness Big 6: - pertussis (whooping cough) - diphtheria - Tetanus - Poliomyelitis - Mumps - Measles
Which immunisations were added to the the Big 6 in 2019?
MMR HepB HiB (h. influenza B) Pneumococcal Rotavirus HPV (TB/BCG is only given to high risk groups, currently)
Which vaccines are not in progress or only given to a certain individuals?
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
What are the main public health importance of immunisation?
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)
What is the vaccine hesitancy cycle?
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
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?
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
Why is tetanus unlikely to ever be eradicated completely?
Spores that cause tetanus are found in the soil
(naturally occurring)
Therefore difficult to eradicate
How infectious is measles?
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
What is herd immunity?
the level of immunity in a population against a specific disease?
How are vaccination rates and herd immunity levels related?
Vaccination rates are PROPORTIONAL to herd immunity levels
What is the benefit of herd immunity?
adequate: necessary to prevent outbreaks of infectious disease
high: also protects vulnerable or unprotected groups
What is the trend of whooping cough incidence and vaccination rates?
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
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?
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
The UK Childhood immunisation schedule is complex. What are the main illnesses covered by it?
- 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