35 Protecting the host: vaccination Flashcards
Vaccination aims to prime adaptive immune system, so second contact will provide a rapid and effective secondary immune response by memory T and B cells.
What are different types of vaccines and examples?
Live attenuated -
- viral - measles, mumps, rubella, vaccinia, varicella, yellow fever, zoster, oral polio, intranasal influenza, rotavirus
- bacterial - BCG, oral typhoid
Inactivated -
- Whole virus - polio, influenza, hepatitis A, rabies, JE
- Whole bacteria - pertussis, cholera, typhoid
Fractions -
- toxoids - diptheria, tetanus
- protein subunits - hepatitis B, influenza, pertussis, HPV 6/11/ 16/ 18
- polysaccharides - pneumococcal, meningococcal, salmonella typhi, Hib
- conjugates - pneumococcal, meningococcal, Hib
Who should not be given live vaccines?
HIV patients
Pregnant
Inactivated vaccines are safe to use
Why are toxoid vaccines used for diptheria/ tetanus?
It is the toxin which is damaging to host, not the bacteria itself. So use inactivated toxoid as vaccine
Inactivated/ protein/ polysaccharide require multiple doses for vaccination. Why is this?
Less immunogenic than vaccines with whole organisms.
Sometimes adjuvants are required to improve immune response through inducing activation of Toll-like receptors on dendritic cells to improve antigen presentation. Certain chemicals can be used as adjuvants, such as aluminium salts, and cytokines IL1, IL2, IFNgamma can help boost immune response
What are problems with vaccine safety?
Live attenuated -
- insufficient attenuation
- reversion to wild type
- admisiter to immunodeficient patient
- contamination other viruses
- foetal damage
Non-living vaccines
- contamination by chemicals
- allergic reaction
- auto-immunity
Why are childrens vaccinations required to be repeated?
Can have maternal antibodies, so do not develop own memory cells
Some vaccines are less immunogenic
What are the two types of polio vaccine?
Three serotypes of polio, vaccine works against all three - trivalent.
But polio-2 and polio-3 has been eliminated, so may only need to use monovalent vaccine in future
Inactivated IPV - Salk 1954
Injectible
Risk if inadequatley killed
Attenuated OPV - Sabin 1957
Oral - easy to administer
Benefits - replicates in intestine produce local immunity IgA, and can be spread to other household members.
Risk of vaccine associated paralytic polio (VAPP)
they both target polio virus 1/ 2/ 3
What are risks of oral polio vaccine? OPV
Can can vaccine associated paralytic polio (VAPP)
OPV virus can be transmitted in community termed circulating vaccine-derived polio viruses cVDPV. If susceptible population, can survive moving between hosts. Mutations slowly develop, and cause paralysis
Why was it difficult to create pneumococcal vaccine?
over 90 serotypes
Most common 23 serotypes included in vaccine
Why does haemophilus vaccine target type b serotype?
six capsular serotypes, but type b causes 95% of disease.
Usually those under 5 affected
Why is influenza vaccine difficult to develop?
Influenza vaccine contains three flu strains -
2 A strains
1 B strain
Antigenic drift - gradual mutation
Antigenic shift - reshuffle of RNA can produce different H/N antigens
Given to people >65 who have weaker immune systems, so may not generate sufficient immune response - immunosenescence
Winter 2020-21
H1N1
H3N2
B
Why is it difficult to produce HIV vaccine?
gp120 can mutate easily
killed virus not sufficiently immunogenic
route of infection via genital tract, means need localised mucosal immunity, which vaccine can’t provide
Adenoviruses are useful as vaccine vectors, why is this?
What are draw backs?
Induce good CD8 T cell response
Some people have already been infected with adenovirus species, and have antibodies to them, so may not generate good immune response
Why was smallpox easy to erradiacte?
highly effective vaccine
Easy to administer vaccine
Single vaccine dose
Infected patients can be easily spotted
Easy to contain patients once diagnosed
Permanent immunity after disease/ vaccination
No animal reservoir
When targeting next disease for erradication, what factors must be present?
Humans must be critical to circulating organism - no animal reservoir
Sensitive/ specific diagnostic tools
Effective vaccine
Why is there a problem with developing a dengue vaccine?
Antibody dependent enhancement between serotypes
Antibodies generated during primary infection with one serotype of virus will not be sufficient to neutralise a second serotype.
However, they might be able to opsonise the secondary virus, and target it for phagocytes. This can lead to dengue haemorrhagic fever or severe dengue on repeat infection
How are organisms inactivated for vaccination?
heat
Chemicals
radiation
some patients have egg allergy. Which vaccine should you seek alternative?
4CMenB DTaP/ PIV/ Hib Influenza MMR Q fever Rotavirus Yellow fever Rabies
Influenza uses embryonated eggs - can use intranasal vaccine instead.
Yellow fever contains eggs and should be avoided
Rabies uses egg embyros and should be avoided
Q fever uses egg embryos and should be avoided
MMR produced in eggs, but is safe as long as no anaphylaxis, as no egg free alternative available
discuss with immunologist if require to give vaccination
VZV susceptible healthcare worker on oncology ward receives varicella vaccine dose through occupational health. She presents two weeks later with vesicular rash. Otherwise well. Not pregnant.
What is next management?
Avoid patient contact until lesions crusted over
<5% develop vesicular rash 5-26 days after vaccination. Given her rash is after two weeks, then it is less likely to be caused by vaccine, and may be new VZV infection.
In any case, vaccine strain is sensitive to aciclovir
- viral PCR of lesion
- viral genome analysis, to see if wild type. Serology does not help differentiate the two
Which vaccines are live attenuated?
Live attenuated -
- viral - measles, mumps, rubella, vaccinia, varicella, yellow fever, zoster, oral polio, intranasal influenza, rotavirus
- bacterial - BCG, oral typhoid
Which vaccines come as combinantions?
MMR
DTaP/IPV/Hib/HepB or DTaP/ IPV/ Hib
Td/ IPV (tetanus)
Influenza A and B
What are advantages of combination vaccines?
Less uncomfortable for patient
Mor efficient vaccination as easier to administer
Higher vaccine uptake
If child has no vaccination history e.g refugee, should they be vaccinated?
Vaccinate as if never had a vaccine
Risk of extra dose is minimal if already vaccinated, and far outways risk of disease
Fully vaccinated pregnant female, what extra booster should be given between 16-32 weeks?
DTaP/ IPV
Inactivated
Studied following outbreak of pertussis in infants
Never give live vaccines in pregnancy, including MMR
One year old girl on high dose steroids for nephrotic syndrome for more than one month.
Which vaccine contraindicated?
DTaP/ IPV/ Hib MenB Inactivated influenza MMR Pneumococcal
MMR live vaccine
Consider those on 40mg prednisolone or above, for more than a week, to be immunosuppressed. This lasts until 3 months after cessation of immunosuppressive drug
Vaccine schedule
8 weeks old
If start vaccination before this, poor immune response as will have maternal antibodies.
Personal Child Health Record (Red Book) records vaccines
DTaP/IPV/Hib/HepB - injection
Meningococcal B (MenB) - injection
Rotavirus - oral
Vaccine schedule
12 weeks old
DTaP/IPV/Hib/HepB - injection
PCV13 - injection
Rotavirus - oral
Vaccine schedule
16 weeks old
DTaP/IPV/Hib/HepB - injection
Meningococcal B (MenB) - injection
Vaccine schedule
Prior to age of 1 year old, what vaccinations should have been given?
DTaP/IPV/Hib/HepB - 3x doses
PCV13 - 1x dose
MenB - 2x doses
Rotavirus - 1x dose
Vaccine schedule
1 year old
Hib/MenC - injection
MenB - injection
PCV13 - injection
MMR - injection
Vaccine schedule
What should child receive by age 2?
DTaP/IPV/Hib/HepB - 3x doses
PCV13 - 2x dose
MenB - 2x doses
Rotavirus - 1x dose
Hib/ Men C - 1x dose
MMR - 1x dose
Vaccine schedule
3-4 year old
LAIV - intranasal
dTaP/IPV - injection
MMR - injection
Vaccine schedule
12-13 years old
14 years old
HPV - 2x injections 6 months apart.
Note - females and males eligible up to age 25. Give three doses if course started after age 15
Td/IPV - injection
MenACWY - injection
Vaccine schedule
What should be given before leaving school?
dTaP/IPV - 5x doses total
MenACWY - 1x dose
MMR - 2x doses
HPV - 2x doses
What is in vaccination schedule for elderly?
65 - pneumococcal single dose/ influenza annual
70 - shingles
At what age should premature infants be vaccinated?
Vaccinate as with chronological age i.e when they were born
This is because even higher risk of childhood disease
Inactivated vaccines - how many can be given together?
How long to wait between doses?
Can give as many as possible
Wait 4 weeks before given another dose of same vaccine is recommended. Some give better response at 8 weeks.
If going travelling, or disease outbreak, and rapid immunisation required, can give vaccines early (by one week). However, this often leads to ineffective response, and another dose may be required
Can these vaccines be given same day?
Yellow fever + MMR
Varicella + MMR
Yellow fever + MMR - both live. Wait 4 weeks between
Varicella + MMR - both live, can give together. But if not given together, wait 4 weeks before given the second one. Study showed outbreak varicella if given too close together. MMR may attenuate response to varicella
Can these vaccines be given on same day?
All live
BCG rotavirus LAIV oral typhoid vaccine yellow fever varicella zoster MMR
Yes, apart from:
Yellow fever and MMR - wait 4 weeks between
Varicella + MMR - only if given together. If not, wait 4 weeks
Household contacts of immunocompromised individual are eligible to receive vaccination, including varicella and seasonal influenza.
What precautions should be taken?
Give inactivated influenza vaccine instead of live vaccine, as risk of spreading to household member
When is vaccination recommended in HIV patients?
Guided by CD4 count - chapter 6 Green book
Avoid BCG at any CD4 count
Splenectomy patients are at risk of infection by encapsulated organisms. What vaccines should they receive?
Pneumococcal
Hib
MenACWY
Influenza - annual
HBV vaccine introduced in 2017 childhood immunisation schedule.
Which other adult groups should receive this vaccine?
HCW
Prison staff
IVDU
Contacts of patient with HBV
Babies born to mothers with chronic HBV
Haemophiliac
CKD
Liver diseases
What is the advice about avoiding school with following conditions?
Chickenpox
Herpes simplex
Rubella
Hand, foot and mouth
In all cases, if one child affected then do not need to contact public health. If multiple cases/ outbreak, then inform public health
Chickenpox - until all vesicles have crusted over
HSV - none. Avoid kissing and contact with the sores.
Cold sores are generally mild and self-limiting
Rubella - four days from onset of rash
Hand, foot and mouth - none
What is the advice about returning to school with following conditions?
Impetigo
Measles
Molluscum contagiosum
Roseola
Impetigo - until lesions are crusted and healed, or 48 hours after commencing antibiotic treatment
Antibiotic treatment speeds healing and reduces the
infectious period
Measles - 4 days from onset of rash
Molluscum contagiosum - none A self-limiting condition. Unless doing contact sports/ swimming - need to cover lesions
Roseola (infantum) - none
What is the advice about returning to school with following conditions?
Scabies
Scarlet fever
Slapped cheek (fifth disease or parvovirus B19)
Scabies - return after first treatment
Scarlet fever - teturn 24 hours after commencing
appropriate antibiotic treatment
Slapped cheek - none
What is the advice about returning to school with following conditions?
Diarrhoeal disease including E.coli, salmonella, shigella, cryptosporidium
Return 48 hours after last episode of diarrhoea/ vomiting
What is the advice about returning to school with following conditions?
Influenza
TB
Whooping cough
Influenza - once recovered
TB - individualised approach
Whooping cough - 48 hours after starting treatment, or 21 days after symptoms started
What is the advice about returning to school with following conditions?
Mumps
Meningitis - bacterial
Glandular fever
HAV
Mumps - exclude for 5 days after onset swelling
Meningitis - bacterial - until recovered
Glandular fever - none
HAV - exclude until 7 days after onset of jaundice
What is difference between eradication and elimination of disease?
Erradication - eliminated worldwide
Elimination - reduced to zero (or small number) of cases in defined geographical area
Which diseases have been erradicated?
Smallpox - erradicated 1980
Rinderpest - cattle plague erradiacted 2001
