Clinical and public health aspects of immunisation Flashcards
Why have there been polio outbreaks recently?
- Large numbers of people fleeing Syria and seeking refuge in nearby countries and Europe, Polio has appeared in areas that were disease free
- Recently in Iraq, which has been disease free for 14 years
Why will we never be able to eradicate tetanus?
- The bacteria that produces the toxin that causes the toxin is found in the soil everywhere
What is herd immunity?
- The level of immunity in a population against a specific disease
- Adequate herd immunity is necessary to prevent outbreaks of infectious diseases
- A high level of herd immunity protects vulnerable unprotected groups
- When vaccination rates are low, herd immunity fails and epidemics can occur
Which vaccines do we give as live attenuated?
- Oral rotavirus
- MMR
- LAIV - nasal flu vaccine
Who now gets the BCG vaccination in UK?
- All infants (at birth) living in areas where the incidence of TB is 40/100,000 or greater
- Infants whose parents or grandparents were born in a country with a TB incidence of 40/100,000 or greater
- Previously unvaccinated new immigrants from high prevalence countries for TB
- Children who would otherwise have been offered BCG in the schools programme will now be screened for TB risk and vaccinated if appropriate
What was the controversy with the MMR vaccine?
- Case series in Lancet 1998 purporting to link MMR vaccine with autism. 12 cases with bowel abnormalities and serious developmental regression (9 had autism) In 8 cases parents reported regression starting shortly after MMR
- Hypothesis that MMR leads to non-specific gut condition permitting the absorption of non-permeable peptides, leading to serious developmental disorders
What were some criticisms of the research into MMR/ autism?
- temporal association with MMR likely to be due to chance
- serious selection bias
- findings not replicable
- post-marketing surveillance (based on >250 million doses) and licensing reviews confirm safety
- epidemiological evidence unsupportive
- Serious conflict of interest & unethical behaviour
What are the high risk groups of people that need to be immunised?
- People travelling abroad
- Certain occupational groups
- Immunodeficient patients
Why do you need to be vaccinated when travelling?
- Will be exposed to new pathogens that not previously met
- Will be areas where certain diseases are much more common
What occupational groups should be vaccinated?
- health care and public safety workers need protection against hepatitis B
- all health care workers should be immune to rubella, tuberculosis and chicken pox
- rabies prophylaxis for laboratory workers handling rabies virus and handlers of imported animals
Why do people with immunodeficiencies need to be vaccinated?
- particularly susceptible to many infections
- may not be able to mount normal immune response to live vaccines
- could suffer severe manifestations e.g. disseminated infection with BCG or paralytic poliomyelitis from oral vaccine virus
- in general live vaccines avoided, inactivated vaccines safe and indicated but may have reduced efficacy
Why do people with hyposplenism need to be vaccinated?
- children and adults with no spleen or with splenic dysfunction (sickle cell /coeliac) are at increased risk from bacterial infections, most commonly caused by encapsulated organisms
- the following vaccines are particularly recommended: pneumococcal; Hib; influenza; men A,C,W,Y & men B
What contraindications are there to vaccinations?
- Acute illness - but minor infections without systemic upset NOT reasons to postpone
- Live vaccines contraindicated in individuals with immunodeficiency and in pregnancy
- Anaphylactic reaction to previous dose
- Specific contraindications for individual vaccines e.g. hypersensitivity to egg contraindicates influenza vaccine
Who is the pertussis vaccine recommended for?
• children with family history or personal history of epilepsy or febrile convulsions
– (give advice on prevention of pyrexia to minimise risk of febrile convulsions occurring)
• children with stable neurological conditions such as cerebral palsy or spina bifida
– (neurological complications more common after whooping cough infection than after pertussis vaccination)
What ethical issues are there with vaccination?
- Balance of public health needs against individuals rights to refuse vaccination
- Importance of informed consent
- Different approaches to increasing immunisation uptake - health education versus legal compulsion
- GP payments for immunisation targets
- Ethical issues raised by MMR scare
- Ethical issues raised by only immunising girls against HPV
- Ethical issues if scarce vaccine
