Bacterial And Viral Vaccines Flashcards
What is the adaptive immune response?
Direct recognition of antigens by B cells, neutralisation of circulating antigens, production of antibodies.
Activation of B cells by T cells, production of long lived plasma and memory B cells
What is involved in T cell mediated immunity?
Activation of T cells by APC
Multiplication of T cells into effector T cells
Cytotoxicity, activation of B cells, memory T cells
What is the principle of vaccine?
Prime immune response so on subsequent encounter the memory response allow a more rapid and rigorous response to be made.
What is active immunity?
Induce and adaptive immune response in the host
What is passive immunity?
Transfer of immune effectors only eg immunoglobulin
What is antisera immunity?
Passive immunity, animal derived, specific for a certain toxin
What are the aims of vaccine?
Produce same immune protection which follows natural infection
Long lasting
Stop spread of infection
equally effective in all individuals
What are examples of immunoglobulin vaccine?
Varicella zoster ig
Human normal ig
Hep b ig
Tetanus ig
What are examples of anti toxins?
Diphtheria anti toxin
Botulinum anti toxin
What are examples of inactivated subunit vaccine?
Diphtheria, tetanus, acellular pertussis, inactivated polio, h influenzae b Influenza Meningococcal C Pneumococcal PCV, PPV HPV HAV HBV
What are examples of live attenuated vaccine?
MMR, opv, rotavirus, yellow fever
What is a live vaccine?
Attenuated strains which replicate in the host, cannot cause disease.
Ilicit good strong long lasting immunity
What are the advantages of live vaccines?
Single dose often sufficient
Strong immune response evoked
Local and systemic immunity
What are the disadvantages of live vaccines?
Potential to revert to virulence Contradicted in immunosuppressed Interference by viruses or vaccines and passive antibody Poor stability Potential for contamination
What are inactivated vaccines?
Suspension of whole intact killed organisms, pertussis, influenza, rabies, hepA
Acellular and subunit vaccines contain one or few components of organism important in protection
What are the advantages of inactivated vaccines?
Stable
Constituents clearly defined
Unable to cause the infection
What are the disadvantages of inactivated vaccines?
Need several doses
Local reactions common
Adjuvant needed
Shorter lasting immunity
What are combination vaccines?
Give several vaccines at one time
Ensure that immune responses are equivalent to single vaccines
Adverse effects are no worse or frequent
What is SSPE?
Sub acute sclerosing pan encephalitis associated with measles
ITP associated with MMR
What is the relationship of adverse events with live and inactivated vaccines?
Live- frequency of adverse events falls with number of doses
Inactivated- frequency of adverse events increases with number of doses
What is the timing of inactivated vaccine reactions?
Generally within 48 hrs following vaccination
What is the timing of live vaccine reactions?
According to time taken for virus to replicate
Measles- malaise, fever, rash, 6-11 days
Rubella- pain, stiffness, swelling of joints, 2nd week
Mumps- parotid swelling, 3rd-6th week
When should you avoid live vaccines? Especially bcg, polio
Patients having chemo for malignancy
Patients less than 6 months after BMT
Children on high dose steroids or cytotoxics
Pregnant women (no evidence of harm from MMR)
What vaccines can be given to HIV positive patients?
MMR, inactivated HIB,DTP, HBV
Not BCG
Not yellow fever vaccine
How do immunoglobulins work?
Provide passive antibody and can be used prophylactically before or after exposure
Cannot be used to test established disease
Can attenuate disease (antitoxins can treat)
What are examples of immunoglobulin therapy?
VZIG- used in susceptible pregnant women, neonates or immunosuppressed patients exposed to chicken pox
HBIG- prevention of HBV, in conjunction with vaccine
NHIG- prevention of HAV, rubella and polio
How is rotavirus given?
Oral liquid vaccine
What is the primary failure of a vaccine?
Individual failures to make adequate immune response to the initial vaccination
What is the secondary failure of vaccine?
Individual makes an adequate immune response but then immunity wanes over time- inactived vaccines, need boosters
Why are live vaccines deferred after 1 yrs old?
Concerned about side fx
Passive maternal antibody will make vaccine ineffective
What is diphtheria?
Resp disease, toxigenic strains of corynebacterium diphtheria or corynebacterium ulcerans
Airborne droplets, infect throat and skin
Incubation 2-7 days
Untreated disease- infectious up to four weeks
Young and elderly
What are the features of diphtheria?
Early signs, mild fever, swollen neck glands, anorexia, malaise, cough
Membranes of dead cells forms in throat,tonsils, larynx or nose
May narrow or occlude the airway leading to respiratory distress
What are the severe symptoms of diphtheria?
Toxin can travel through bloodstream causing extensive organ damage, neurological and heart complications
Death- occurs in 5-10% cases
Current state of diphtheria in UK?
Associated with recent travel to endemic countries
Can make a comeback if immunisation is not maintained
Approx 50% of UK adults over 30 years have antibody titres below lower protection threshold
What is tetanus?
Clostridium tetani
Non communicable, no herd immunity
Form spores, can survive in environment for years
Can occur if wound or cut is infected by soil or manure
Incubation 4-21 days, all ages
Recovered ppl still need immunisation
Where the vernalised symptoms of tetany?
Lock jaw, neck stiffness, difficultly swallowing, stiffness of stomach, spasms, sweating and fever
Complications- fractures, hypertension, laryngospasm, pulmonary embolism, aspiration and death
What is the prevention of tetanus?
5 doses of tetanus at appropriate intervals
Early treatment with tetanus immunoglobulin for heavily contaminated wounds
Early recognition of potential tetanus wounds
Continued vigilance for early signs
What is pertussis?
URI, paroxysmal coughing of >14-21 days duration Bordatella pertussis/parapertussis Vaccine-preventable Immunity is incomplete UK resurgence
What are the 3 phases of pertussis?
Catarrhal phase- indistinguishable from other URI, infectious
Paroxysmal phase- coughing, inspiratory whoop, vomiting, seizures, apnoeic episodes
Convalescent phase- resolution, but dry cough may persist for months
3 times 2 weeks
What pertussis vaccine is used?
Sept 2004- 5aP vaccine, as efficacious as previously used whole cell vaccine
Incidence of local and systemic reactions lower with aP than wP
What are the current issues for pertussis?
High vaccine coverage, some evidence of waning with age
Good control in those most vulnerable, remains most common vaccine preventable disease in less than 1 year old
Recommended for pregnant women 28 weeks
What is poliomyelitis?
Types 1-3, transmitted via faeces, or pharyngeal secretions of infected person
Incubation 3-21 days
Virus can be excreted for up to six weeks in faces and 2 weeks in saliva
Most infectious- before and 1-2 weeks after onset of paralysis
What are symptoms of poliomyelitis?
Can be asymptomatic
Mild influenza like symptoms
Neck stiffness, back and legs- aseptic meningitis
What is paralytic polio?
Less than1% results in flaccid paralysis
1-10 days after prodromal illness and progresses
Loss of limb use, lungs
Degree of recovery variable
What polio vaccine is used?
Inactivated,not avoid risk of vaccine associated paralytic polio from live
Opv available for outbreak control
What is meningococcal disease?
NM, gram negative diplococci, 13 serogroups, B and C common in UK
Recent increase in severe death from men W
Nasal carriage
Meningitis and septicaemia, 1 in 8 long term sequlae
What vaccine is used for MenC?
Conjugate- purified capsular polysaccharides chemically joined to tetanus or diphtheria carrier proteins
Generates T cell dependant immune response and produces memory
Recombinant meningococcal vaccine b intro in September 2015, may provide pan meningococcal protection
What is IPD?
Sp invades lung parenchyma, bloodstream and CNS, joint fluid, pleural fluid, pericardial fluid
Non invasive- otitis media, sinusitis, bronchitis
When does IPD occur?
5000-6000 cases reported to HPA, occur in December and jan
What are the risk factors for IPD?
Male more than female, under 1 year more than50 Winter viral RTi association Chronic lung disease Smoking Alcoholism Immunosuppressed
What is the leading cause of meningitis in the UK?
Pneumococcal
What is the immunity to strep pneumonia?
Colonisation- indices protective capsular serotype specific antibody Cd4 T cell immunity important for immune memory and class switching Cd4 T cell deficient conditions show increased susceptibility to pneumo
What is PPV?
Purified polysaccharide vaccine, 23 serotypes covering 90% isolates encountered in IPD
Safe and immunogenic after single dose
60% effective, DOESNT work in children
Polysaccharide antigens can activate B cells by t independent means only resulting in igM production
What vaccine is now used for pneumo?
Prevenar 13- not recommend for adults or children more than 5 years old, use pneumovax
What is measles?
Caused by morbillivirus
1-4 year olds, nose and throat secretions
Transmission period- beginning of symptoms to 4 days after rash
Incubation- 7-18 days
What are the symptoms of measles?
Cough, runny nose, conjunctivitis, koplik’s spots on buccal mucosa
Rash, spreads from face to body, hands and feet over 3 days
Lasts 5-6 days
Diarrhoea
Neurological involvement
What are the complications of measles?
Severe diarrhoea, dehydration Pneumonia, commenest cause of death Encephalitis also develops SSPE Death
What is mumps?
Acute viral illness caused by paramyxovirus
Transmitted through airborne droplets, incubation 14-25 days
Transmissible for several days before the parotid swelling and several days after it
What are the symptoms of mumps?
Headache, fever, parotid swelling
Photophobia, neck stiffness can develop
Some asymptomatic, severe in adults
What are the complications of mumps?
Pancreatitis, oophoritis, Orchitis,
Neurological, deafness, nephritis
Cardiac abnormalities
What is rubella?
German measles, caused by Togavirus
Direct or droplet contact with nasopharyngeal secretions
Incubation 14-21 days
Infecvtiviry- 1 weeks before, 5-7 days after onset of rash
Peak incidence of infection- late winter, early spring
What are the symptoms of rubella?
Mild illness, swollen lymph glands, low grade fever, malaise, conjunctivitis
Maculo- popular discreet rash develops on face, neck and body
Swollen joints and joint pain common in adults
What are the complications of rubella in pregnancy?
Risk of foetal damage greatest at 10 weeks
Cardiac, auditory, ophthalmic, neurological problems
What is contained in the MMR vaccine?
Enders Edmonston strain measles
RA27/3 rubella
Jeryl Lynn mumps
What is hepatitis B virus?
Infection of liver, incubation from 40-160 days
Extremely infectious
What are the modes of transmission for hep B?
Exposure to infected blood or body fluids
Perinatal transmission, parenteral, sexual
When should neonates be vaccinated?
Babies born to infected mothers, at birth
Chronically infected mothers, or acute episode during pregnancy
Babies born to highly infectious mothers should also receive hep B immunoglobulin
What vaccines do we want?
HIV HCV CMV DENGUE MALARIA Diarrhoea, RSV
What is the innate immunity response?
Entry of pathogens into tissue
Recruitment of specific effector cells, phagocytes, macrophages, neutrophils, recognition and internalisation
