L10 - trends in vaccinology 1

• what is a vaccine?

  biological preparation that stimulates the immune system to recognise and defend against a specific pathogen/harmful microbe
• what does a vaccine contain?

  contains an antigen/mix of antigens from the target pathogen

  • live pathogens
  • inactivated pathogens
  • subunits of pathogens
  • genetic material eg mRNA from the pathogen
• a vaccine is a method of educating the body's natural defence against infection/harm
• there are large variety of vaccine types
• immunisation


  process of inducing immunity in an individual against a specific pathogen or disease

  vaccines are primary tools for achieving immunisation

  • can be active or passive
• antigen


  molecule or part of pathogen that triggers an immune response

  in context of vaccine - antigens are key components that the immune system recognises
• immunity


  ability of immune system to protect body from infection or diseases

  vaccines aim to establish immunity without causing the actual disease
• herd immunity


  occurs when sufficiently high percentage of a population becomes immune to disease, either through vaccination or previous infection

  this reduces the likelihood of disease transmission and protects those who cannot be vaccinated
• vaccination - the essentials

  2.3 million/year lives vaccinations save per year globally
• vaccination saves lives

  most effective public health tool after clean water
• vaccines lead to eradication eg smallpox
• vaccine developments


  timeline

  
• types of vaccine

  
• current uk schedule - look over
• indirect protection

  no vaccination - infection passes from individual with disease to susceptible individual and spreads throughout population

  vaccine coverage below threshold for herd protection - infection can still pass to susceptible individuals and spread throughout population except those who are vaccinated

  vaccine coverage above threshold for herd protection - infection cannot spread in population and susceptible individuals are indirectly protected by vaccinated individuals
• timing of vaccines

  maternal vaccines - protect young individuals from first day of life

  infant vaccines - protection from invasive bacterial infections and diarrhoea

  childhood vaccines - protection from severe complications of viral infections - boosting immunity from previous vaccination

  adolescent vaccines - protection from cervical cancer and meningitis - boosting immunity from previous vaccination
• uk vaccination schedule


  look at
• meningococcal vaccines - indirect effects

  vaccinate kids that spread it

  some spread it <5 mainly reduce disease incidence if vaccinate them
• vaccine delivery vs mucosal

  route of vaccine delivery can impact magnitude, quality and locations of immune response

  most vaccines are given via intramuscular or subcutaneous route
• nasal flu vaccine (LAIV)


  LAIV = live attenuated influenza vaccine

  delivered mucosally via nasal spray

  live trivalent A(H1N1) A(H3N2) B - from 2014 quadrivalent with 2 Bs

  seasonal vaccine - reformulated annually

  licensed 2-18 year olds

  programme rolling out in UK

  • 2013 - all 2+3 year olds
  • 2014 - all 2,3+4 year olds
  • 2015-16 - 5,6,7 year olds as well

  mainly given to protect the elderly
• vaccine delivery - systemic vs mucosal

  parenteral

  • most establish route
  • many different delivery options
  • elicits systemic immune responses

  mucosal:

  advantages

  • early control infection
  • effective control non-invasive infections
  • obviates need for injection
  • wide-spread response

  limitations

  • difficult to induce effective IgA response in practice
  • antigen instability at mucosal sites
• human papilloma virus (HPV)

  • over 100 types
  • some can cause cervical and penile cancer (oncovirus)
  • Harald zur Hausen - identified some HPVs as oncogenic

  oncogenic - certain serotypes can predispose survival of cancer - landmark discovery

  • HPV 16 and HPV 18 are responsible for most HPV related cancers
• HPV vaccines- virus like particles - lok at #
• HPV vaccines

  3 vaccines

  • bivalent 16+18 cancer causing types
  • quadrivalent 6+11 genital wart causing types plus 16+18
  • nonavalent - quad plus 5 more types 31, 33, 45, 52, 58

  2 doses over 6 months

  mostly used in teenage girls
• look at australia graphs agains
• WHO policy - elimination of cervical cancer

  • massive roll out - shortages
  • biggest impact in females before sexual debut
  • until more vaccine available, giving to older girls ant boys will prevent less cancer than giving vaccine to 11 year old girls
• malaria vaccines - recent progress - lok at