An Overview Of Vaccines Flashcards
1
Q
Learning Objectives
A
- List the vaccines routinely used in all countries and describe the diseases against which they are used
Appreciate the impact vaccines have had on childhood infectious diseases - Explain the reasons for differences in vaccine use for different countries
- Describe the different types of vaccines
- Understand the rationale for maternal immunisation against pertussis
- Explain the difficulties in delivering vaccines to ‘in need’ populations within LICs and LMICs
- Explain the different types of COVID-19 vaccines in the context of global health
2
Q
Describe Diptheria
A
- Infectious respiratory disease caused by toxigenic strains of bacteria Corynebacterium diphtheriae or Corynebacterium ulcerans
- Transmitted via airborne droplets
- Bacteria infect the throat and sometimes the skin
- Incubation period from 2-7 days
- Patients with untreated disease may be infectious for up to four weeks
- Affects people of all ages - most serious in young infants and the elderly
3
Q
List the features of diptheria
A
- Early signs: mild fever, swollen neck glands, anorexia, malaise, cough
- 2-3 days: membrane of dead cells forms in throat, tonsils, larynx or nose
- May narrow or occlude the airway leading to respiratory distress
4
Q
What are the severe symptoms of Diptheria?
A
- Toxin can travel through bloodstream causing extensive organ damage, neurological and heart complications
- Death occurs in 5-10% of cases
- Milder infection can still occur in people who are partially vaccinated or were vaccinated a long time ago
5
Q
Describe the cases and deaths of Diptheria in England and Wales between 1914 and 2009
A
- Cases kept fluctuating between 400k and 750k from 1914 to 1939
- Cases then sharply dropped after 1939
- deaths slowly declined from 1914 to 1949
6
Q
Describe Tetanus
A
- Caused by bacterium Clostridium tetani
- Non-communicable therefore vaccination required for protection (no herd immunity)
- 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
7
Q
List the symptoms of tetanus
A
- Initially: muscle stiffness of the jaw (“Lockjaw”) 50% cases
- Followed by: neck stiffness, difficulty swallowing, stiffness of stomach muscles, muscle spasms, sweating and fever
- Complications Include: Fractures, Hypertension, Laryngospasm, Pulmonary embolism, Aspiration, Death
8
Q
What is neonatal tetanus?
A
- More frequent in developing countries
- Infant born without protective passive immunity
- Infection of the umbilical cord stump
- High fatality rate without therapy
9
Q
Describe how the maternal vaccination of tetanus is used
A
- WHO: 2 doses of TT during 1st pregnancy and 1 dose in each pregnancy until 5 doses
- 47 countries eliminated MNT between 2000 - 2020
- This leaves 12 countries yet to eliminate MNT
10
Q
Describe Pertusis (Whooping Cough)
A
- Disease of the respiratory tract caused by Bordatella pertussis
- 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
11
Q
List the symptoms of pertussis
A
- Initially: cold-like symptoms - 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
12
Q
What are the complications of pertussis?
A
- 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
13
Q
What is the vaccine for pertussis?
A
- There are 2 types:
- Whole cell vaccine (wP) – suspension of whole killed Bordetella pertussis organisms
- Acellular vaccines (aP) – contain 2, 3, or 5 highly purified components from the B pertussis organism
14
Q
Describe the effectiveness of the pertussis vaccination in pregnancy
A
- 20 deaths in babies with confirmed pertussis born after programme introduction: 18 not vaccinated; 2 vaccinated too late VD
15
Q
Describe the pertussis infection in young UK infants
A
- Dose 1 received at week 8
- Dose 2 received at week 12
- Dose 3 received at week 16
- Rate of infection peaks at week 3 and steadily starts to decrease afterwards from 70 to 10 by week 17
16
Q
Describe the effectiveness of the pertussis vaccination in pregnancy
A
- At <3 months, vaccination effectiveness was 91%
- At <2 months, vaccination effectiveness was 90%
17
Q
Describe the poliovirus
A
- Three types - I, II, & III
- Virus enters via the mouth
- Replicates in pharynx and GI tract
- Invades local lymph tissue
- Enters blood stream and may infect cells of central nervous system causing aseptic meningitis
- More rarely replicates in and destroys the motor neurones which activate the muscles (~1:100 infections)
18
Q
Describe the dynamics of poliomyelitis
A
- Transmitted through contact with the faeces or pharyngeal secretions of an infected person
- Incubation period: ranges from 3 – 21 days
- Infectiousness: not precise but transmission is possible as long as virus is excreted
- Virus can be excreted for up to six weeks in the faeces and two weeks in saliva
- Most infectious immediately before and 1-2 weeks after onset of paralytic disease
19
Q
Describe paralytic polio
A
- Less than 1% of all polio infections result in flaccid paralysis
- Paralysis develops 1-10 days after prodromal illness and progresses for 2-3 days
- The use of one or both arms or legs may be lost and breathing may not be possible without help of a respirator.
The degree of recovery varies from person to person
20
Q
What was the polio vaccine?
A
- Until Oct 2004, live polio vaccine, given by mouth was used in UK
- Very effective and stimulates immune response in the blood and gut
•Very rarely (1 in a million) vaccine virus reverts back to wild type causing Vaccine Associated Paralytic Polio (VAPP) - Cases of VAPP have been reported in recipients of OPV and in contacts of the recipients
- OPV replaced by IPV
21
Q
Visit slides for diagrams
A
22
Q
Describe the rotavirus
A
- Most common cause of diarrhea in children aged ≤5 years worldwide
- Highly infectious: only 10-00 virus particles needed for infection
- Transmission mainly through the faeco-oral route
- Contaminated food/water
- Contact with contaminated objects or surfaces
- Can live for hours on hands and get spread from by human contact
- May remain viable in the environment for months if not disinfected
- Sometimes through respiratory droplets: by sneezing and coughing
- Children can spread rotaviruses both before and after they become sick with diarrhea increased risk in daycare facilities
- Contagiousness period 8 days (>30 days if immunocompromised)
23
Q
List the signs and symptoms of rotavirus
A
- Sudden onset abdominal pain & vomiting - usually lasts 24-48 hours
- Profuse watery diarrhea - lasting 3 to 8 days (median 6 days)
- Mild to Severe dehydration – if untreated can result in death
- Fever
- Adults and older children can also become infected – mild symptoms, often asymptomatic
- DIAGNOSIS: often based on symptoms and physical examination, but can test stools for rotavirus antigen
- TREATMENT: supportive care, rehydration (preferably orally), may need hospital admission for IV fluids.
24
Q
Describe the burden of rotavirus
A
- Globally:
- Nearly every child will have rotavirus gastroenteritis by 5 years of age
- 1 in 5 will visit an outpatient clinic
- 1 in 60 will be hospitalised
- 1 in 293 will die due to the disease (600,000 deaths annually)
- In England and Wales, in children <5 years of age: Estimated annual cost of £14.8 million in E&W
25
Describe the vaccine efficacy for the 2 types of rotavirus vaccines
VD
26
Describe measles
- Extremely contagious viral illness caused by Morbillivirus
- Most common in 1-4 year olds
- Spread by contact with nose and throat secretions and in airborne droplets released when an infected person sneezes or coughs
- Transmission period is from beginning of first symptoms to 4 days after appearance of the rash
- Incubation period ranges from 7 to 18 days
27
List the symptoms of measles
- Early symptoms include:
- Runny nose
- Cough
- Red and watery eyes and
- Small white spots inside the cheeks (Koplik’s spots)
28
List the symptoms of measles part 2
- Followed by:
- A slightly raised rash develops, spreading from the face and upper neck to the body and then to the hands and feet over a period of three days
- Rash lasts 5-6 days
- Loss of appetite and loose stools
29
How do we prevent tuberculosis in the UK?
- Bacille – Calmette – Guérin (BCG vaccine) contains a live attenuated strain from mycobacterium bovis
- Introduced into general use in 1953, with national school immunisation programme aimed at 11-13 yr olds
- 2005: Universal programme of offering BCG to school age children replaced by a targeted neonatal and other risk group-based programme
- GLOBALLY: given to more children than any other vaccine!
30
What is recommended for the UK BCG?
- All babies, at or soon after birth, living in areas where the incidence of TB is 40/100,000 or greater
- Children (<16yrs) whose parents or grandparents have lived in a country with a TB prevalence of 40/100,000 or higher
- Previously unvaccinated new immigrants from high prevalence countries countries for TB
- Contacts of cases of TB
- Travellers (<16yrs) to countries with high TB prevalence for >3m
- Occupational e.g. Healthcare workers <35yrs
31
What other vaccines do we need around the world?
- HIV
- Malaria
- Better TB…
- RSV
- Group B streptococcus
- Group A streptococcus
- Staphylococcus aureus, Klebsiella, E. coli
- CMV, HSV, EBV
32
Describe Haemophilus influenzae type b (Hib) disease
- Caused by infection with Haemophilus influenzae bacteria
- 6 (a-f) capsular serotypes cause disease in man
- 99% of typeable strains in pre-vaccine era were type b
- Transmission occurs from coughing, sneezing, close contact with infected person.
- Healthy individuals can carry Hib bacteria in their nose and throat without symptoms
- Incubation period less than 10 days
- Non-typeable (non-capsular) infections cause invasive disease less commonly but become important in post-vaccine era
33
Describe the features of the HIB disease
- Most common presentation of invasive Hib is meningitis, frequently accompanied by bacteraemia (60%)
- 15% of cases present with epiglottitis
- Bacteraemia without any other concomitant infection, occurs in 10% of cases
- Remainder made up of cases of septic arthritis, osteomyelitis, cellulitis, pneumonia, and pericarditis
34
Describe the burden of disease caused by haemophilus influenzae type b in children younger than 5 years
VD
35
Describe Streptococcus pneumoniae
- Carried in the nose and throat
- Transmitted through infected droplets through coughing, sneezing & close contact
- Whether infection develops or not depends on immune system and on virulence of serotype acquired
- Over 90 serotypes identified (based on differences in polysaccharides in outer coating)
- Not all 90 serotypes cause disease – about 80% invasive infections in UK children caused by just 8-10 of these types
36
What is GAVI?
- Gavi is an international organisation that was created in 2000 to improve access to new and underused vaccines for children living in the world’s poorest countries.
- Gavi is the Vaccine Alliance, which brings together public and private sectors with the shared goal of creating equal access to vaccines for children, wherever they live.
37
What is GAVI? (PART 2)
- Towards the end of the 20th century, global immunisation efforts were beginning to plateau. Despite the promising progress of the previous two decades, by the Expanded Programme on Immunization (EPI), there were still 30 million children living in poor countries who were not fully immunised. Coverage was stagnating and in some places even declining.
- New vaccines were becoming available, beyond the original six EPI vaccines, virtually none were reaching children in developing countries, those who needed them most, because they were too expensive.
38
What is GAVI? (PART 3)
- Initial US$ 750 million five-year pledge from the Bill & Melinda Gates Foundation
- By 2014 reaching 440 million additional children since its creation and preventing six million deaths in the process.
- Innovative finance includes the International Finance Facility for Immunisation (IFFIm) and the Advance Market Commitment (AMC). Direct contributions include grants and agreements from donor governments, and personal and private sector philanthropy facilitated by the GAVI Campaign.
39
Describe the symptoms of meningitis or Septicaemia
- Rash
- Fever/ Vomiting
- Cold hands and feet
- Rapid breathing
- Joint/ stomach/ muscle ache
- Drowsiness/ LOC
- Stiff neck
- Dislike of bright lights
40
Describe the meningococcal disease
- Caused by infection with Bacteria Neisseria meningitidis
- Gram negative diplococci, divided into 13 serogroups
- Groups B and C are most common in the UK
- Less common serogroups include A, Y, W135, and Z
- Healthy individuals carry the bacteria in their nose and throat without symptoms
- Transmission occurs through frequent and prolonged contact with respiratory secretions of a carrier from coughing, sneezing, kissing
41
Describe meningococcal disease further
- Most common presentation of meningococcal disease is meningitis and septicaemia
- Disease onset is sudden
- 1 in 8 people who recover are left with long term complications
- Case fatality rate is high but varies with age, serogroup, clinical presentation and prompt treatment
42
Describe the complications of Rebella infection in pregnancy
- Congenital rubella syndrome (CRS)
- Risk of foetal damage is estimated at:
- 90% in first 10 weeks
- 10-20% by 16 weeks
- Rare after 20 weeks
- Defects include cardiac, auditory, ophthalmic, neurological problems
43
Describe Hepatits B
- Infection of the liver caused by Hepatitis B virus
- The incubation period ranges from 40 to 160 days
- Extremely infectious (x100 more infectious than HIV)
- World-wide, about 1 million people die from acute and chronic HB infection, making it one of the major causes of morbidity and mortality in humans
44
Describe the modes of transmission for hepatitis B
- The virus is transmitted by exposure to infected blood or body fluids
- Transmission most commonly occurs:
- Perinatal transmission: mother to child
- Parenteral transmission: exposure to blood/other infective fluids
- Sexual transmission: contact with an infected person
45
List the Symptoms of Hepatitis B infection
- Acute infection:
- Many new infections are subclinical or have flu-like illness
- Anorexia, nausea, ache in the right upper abdomen, mild fever, malaise, disinclination to smoke or drink
- Jaundice occurs in 10% of younger children and 30-50% of adults
- Chronic infection complications include: Hepatic cirrhosis, Necrosis, Chronic active hepatitis, Hepatocellular carcinoma
