Overview of Vaccines & Epidemiology of Vaccine Related Disease Flashcards
What is the general spead of vaccine coverage?
-
Limited no of vaccines
- Many reasons
- Logistics
- Cost
- Cold chain
- More vaccines in HICs than LMICs
- Vaccine coverage reflect local disease epidemiology
- As diseases go under control vaccine coverage could decrease
- Vaccine schedules differ across countries
- Child and adult schedules
- In LICs there is limited differentiation between child and adult vaccination
- Must accelerate the introduction of important vaccines in LICs
- Whole cell vaccines= LICs Acellular vaccines= HICs
What is diptheria?
- Infectious respiratory disease caused by toxigenic strains of bacteria Corynebacterium diphtheriae or Corynebacterium ulcerans
- Transmitted via airborne droplets
- Bacteria infect the throat + the skin
-
Incubation period:
- 2-7 days before the disease occurs
- Patients with untreated disease may be infectious for up to 4 weeks
- Affects people of all ages- most serious in young infants and the elderly
What are the features of diptheria?
- Early symptoms;
- Mild fever
- swollen neck glands
- anorexia
- malaise
- cough
- 2-3 days
- Membrane of dead cells forms in the throat, tonsils, larynx or nose
- May narrow or occlude the airway
- lead to respiratory distress
What are the severe symptoms of diptheria?
- Toxin can travel through bloodstream causing extensive organ damage, neurological and heart complications (arrhythmia)
- Death occurs in 5-10% of cases
- Milder infections can still occur in people who are partically vaccinated/ were vaccinated a long time ago
Describe diptheria trends over the past century
High number of cases between 1914 and 1944
Decline is not all due to vaccine
There has been increased hygine, better public health resources , better access to public health
Describe diptheria vaccine coverage in infants
Access to DTP3 vaccine between the 80s and 2010s has increased
Greater than the WHO UNICEF estimates
- Decline of cases over time
- Vaccine coverage has fallen over the pandemic
- This poses a public health concern if there would be a resurgence of the disease due to a decrease in vaccine coverage over the pandemic
Non uniform coverage globally
Countries like nigeria have les than 50% coverage of the DTP3 vaccine
What is tetanus?
- Caused by bacterium Clostridium tetani
- Non-communicable therefore vaccination required for protection (no herd immunity)
- Tetanus is ubiquitous and will not be gotten rid of thus we must maintain their vaccination
- Bacteria form spores that can survive in the environment for years
- Tetanus may occur if a wound or cut is infected by soil or manure
- Incubation:
- period 4-21 days
- Affects people of all ages
- People who recover from tetanus do not have natural immunity therefore need to be immunised
What are the symptoms of tetanus?
- Generalised
Initial: muscle stiffness of the jaw (“Lockjaw”) 50% cases
Later symptoms: neck stiffness, difficulty swallowing, stiffness of stomach muscles, muscle spasms, sweating and fever
Complications:
- Fractures
- Hypertension
- Laryngospasm
- Pulmonary embolism
- Aspiration
- Death
Where does neonatal tetanus occur?
- More frequent in developing countries
- Children still suffer with tetanus due to poor hygine
- Infant born without protective passive immunity
- Infection of the umbilical cord stump
- High fatality rate without therapy
Describe the reported cases of tetanus globally by year and gae between 1985 and 2017
- numbers
- In the Uk, most of the cases had occurred over the age of 65
- This is largely associated with waning vaccine protection ( like women 65+ because they were less vaccinated than men.
- Men received extra vaccines in ww2
What is the solution to tetanus?
- WHO: 2 doses of TT during 1st pregnancy and 1 dose in each pregnancy until 5 doses
- The maternal neonatal tetanus elimination program (through the WHO has vaccinated millions of pregnant women with the tetanus toxoid vaccine)
- Over 70% have received the vaccine over the year
- 47 countries eliminated MNT between 2000 and June 2020
- Again, countries like nigeria have failed to eliminate tetanus
What is pertussis?
- Disease of the respiratory tract caused by Bordatella pertussis bacteria
- Spread easily from person-to-person in droplets produced by coughing or sneezing
- Most dangerous in children under 1 year, most severe in young infants
- Incubation period 6-20 days with a range of 4 - 21 days
- Infectious from 6 days after exposure to 3 weeks after onset of cough
- Duration of illness can be 2-3 months
What are the symptoms of pertussis?
- Called whooping cough
- Lasts long time (many weeks)
- Initially: _cold-like symptom_s - runny nose, watery eyes, sneezing, fever and a mild cough
- Followed by: gradually worsening cough, which develops to paroxysms of coughing followed by characteristic whoop
What are the complications for pertussis?
- Respiratory – collapsed lung and/or pneumonia
- Neurological – lack of oxygen leading to altered consciousness, convulsions, permanent brain damage, death
- Severe weight loss and dehydration due to vomiting
- Sudden death - babies may stop breathing, apnoeic attacks
What are the vaccine methods for pertussis?
-
Whole cell vaccine (wP) – suspension of whole killed Bordetella pertussis organisms
- Effective
- Associated with side effects because the vaccine includes antigens to trigger an immune response, but it also contains polysaccharides that cause other side effects (like fever, vomiting etc)
-
Acellular vaccines (aP) – contain 2, 3, or 5 highly purified components from the B pertussis organism
- This only contains the antigens
- Less likely to cause side effects
- More likely for immunity to fade, compared to whole cell vaccine
What are the measles notifications?
- Loss of confidence of the MMR vaccine
- Andrew wakefield
- He suggested that MMR could predispose children to autism
- However, shortcuts were made in the paper
- Therefore, vaccine coverage fell, especially in London
However, this was disproven and coverage arose again
