Immunization and Disease Prevention Flashcards
What does WHO say is the 2 public health interventions that have the greatest impact?
- clean water
- vaccines
Aim for the Malawi Expanded Programme on Immunization (EPI)?
Aims to decrease childhood morbidity and mortality from vaccine preventable diseases
- It is largely based on the WHO-recommended immunization schedule and guidelines
What is an immunization?
It is the process of inducing immunity against a specific disease
What are the types of immunity?
- passive(through administration of antibody)
- active(antigen or toxoid administration)
- Produces a prolonged humoral and/or cellular immune response
- Vaccines can be whole or parts of microorganisms
What are the types of vaccines?
- bacterial vaccines
- viral vaccines
What are bacterial vaccines?
- Whole organism e.g., inactivated oral typhoid vaccine
- Inactivated toxins e.g., diphtheria and tetanus vaccines
- Specific antigens e.g., Haemophilus influenzae b and pneumococcal polysaccharide vaccines
What are viral vaccines?
- Attenuated live viruses e.g. measles, polio and rotavirus vaccines
- Viral components e.g. hepatitis B vaccines
What is Bacillus Calmette-Guerin (BCG)?
- Freeze-dried live attenuated strain of Mycobacterium bovis
- Limited effectiveness in preventing pulmonary tuberculosis (about 50% efficacy)
- More (80%) effective against milliary and meningeal TB
- Contraindicated in symptomatic HIV infection (AIDS) or immunosuppressive conditions
What is the measles vaccine?
- Attenuated virus
- The WHO recommends immunization at nine months
- Earlier immunization (e.g at six months) would have limited immunogenicity
What is pneumococcal conjugate vaccine (PCV)?
- Includes the 13 of the 93 pneumococcal serotypes
- Three doses given at 6, 10 and 14 weeks
- Less efficacious in HIV-infected children (65% vs 83%) in reducing invasive pneumococcal disease
PCV has resulted in?
- Reduction in hospitalization for all cause pneumonia (30—40%)
- Reduction of acute otitis media in middle and high income countries (15-40% )
What is hepatitis B vaccine?
- Recombinant hepatitis B vaccine provided at 6,10,14 weeks
- Infants born to HBsAg+ mothers should receive both 0.5ml HepB immunoglobulin within 12 hours of birth and hepatitis B vaccine
Describe the Hemophilus influenzae type b (Hib) vaccine?
- Is part of a multi-component vaccine (DPT-HepB-Hib)
- Protects against epiglottitis, Hib meningitis, pneumonia, and osteomyelitis
What is the impact of Hib?
- has reduced invasive hib disease ( > 90%)
- Has reduced radiographically proved pneumonia (20-25%)
Describe the pertussis vaccine?
used against whooping cough
Describe the Diptheria toxoid vaccine?
- Highly effective in inducing antibodies that neutralize toxin, thus protecting against diptheria
- It may not protect against acquisition or carriage of Corynebacterium diptheriae
What are the 2 kinds available for polio routine immunization?
- Inactivated polio vaccine (IPV)
- Live attenuated oral polio vaccine (OPV)
Describe the OPV polio vaccine?
- Rare (1/2,000,000) risk of causing vaccine-associated paralytic poliomyelitis
- Induces greater mucosal immunity than IPV
Describe the Rota virus?
- Live attenuated vaccine provided at 6 week and 10 weeks
- Slight increased risk of intussusception with rota virus vaccine use
Malawi immunization schedule?
- at birth
- BCG, OPV 0 - 6 weeks
- OPV 1, Rota 1, Pentavalent 1, PCV 1 - 10 weeks
- OPV 2, Rota 2, Pentavalent 2, PCV 2 - 14 weeks
- OPV 3, Pentavalent 3, PCV 3, IPV - 5 months
- MV 1 - 6 months
- MV 2 - 7 months
- MV 3 - 9 months
- MR 1 - 15 months
- MR 2 - 22 months
- MV 4
HPV vaccine vaccination (9 year old girls) schedule?
9 years
- HPVV 1, HPVV 2 (6 months after HPVV 1)
- Intra muscular
- upper arm
- 0.5 ml
Note: HPV is major causes of cervical cancer in women and laryngeal papilloma in children
Td vaccination (women of child bearing age) schedule?
15 - 45 years
- Td 1 at contact
- Td 2 (1 month after Td 1)
- Td 3 (6 months after Td 2)
- Td 4 (1 year after Td 3)
- Td 5 (1 year after Td 4)
> intra muscular
> right upper arm
> 0.5 ml
Established vaccine not included in the Malawi EPI program?
- Measles, Mumps and Rubella (MMR) - Malawi has the MR component
- Influenza vaccine
- Hepatitis A
- Varicella vaccine (attenuated vaccine - contraindicated in advanced immunosupressive disorders and in pregnancy)
- Meningococcal C vaccine
Immunization practical considerations?
- Vaccines lose their potency if not stored and transported correctly
- Vaccines should be refrigerated between 2 °C and 8 °C
- The “cold chain” from manufacturer to administration of vaccines is a critical part of EPI
- Vaccines (except for freeze-dried BCG, OPV, MR) should not be frozen
- Diluent is never frozen
- Some vaccines (e.g BCG, MR) lose potency if exposed to light
- Reconstituted vaccines should be checked for signs of deterioration, such as a change in colour or clarity
- Reconstituted vaccines deteriorates rapidly at room temperature and should be used within 12 hours
Contraindications to vaccines?
- Anaphylactic reaction to a prior dose (vaccines grown in eggs, gelatin stabilizers; antimicrobial agents)
- Defer vaccine in moderate to severe acute illnesses - mild illness may be vaccinated
- Children receiving corticosteroids (≥2 mg/kg/day or ≥20 mg/day of prednisone or equivalent) for 14 or more days
- Malignant disease, immunosuppressive drugs
Which immunodeficient conditions can be given live vaccines?
- HIV
- severe malnutrition
Host risk factors for hospital acquired infections?
- Recent invasive procedures
- Presence of catheters or other devices
- Prolonged use of antibiotics
- Contaminated physical environment
- Exposure to people with active contagious infections (patients, visitors, or healthcare providers)
- Colonized with invasive microorganisms
- Anatomic abnormalities (dermal sinuses, cleft palate, obstructive uropathy)
- Abnormal skin
- Organ dysfunction e.g. heart failure, bone marrow suppression
- Malnutrition
- Underlying diseases or comorbidities
How are recent invasive procedures risk factors for hospital acquired infections?
- Breaching normal anatomic host barriers
- Provide direct access to sterile anatomic sites
- Disrupt patterns of normally protective flow of mucus (e.g., nasotracheal tubes and sinus ostia)
- Tubes placed through the nose may disturb function of cilia an obstruct drainage of sinuses
How is prolonged use of antibiotics a risk factor for HAIs?
Can alter the composition of bowel flora and encourage the multiplication and emergence of toxigenic or invasive organisms (e.gClostridium difficileandSalmonellaspp)
Agents of infection transmission?
- Thehands
- Medical equipment
- Toys
- Hospital and office furnishings
- Phones
- Computer keyboards
- Neckties
- these inanimate objects serve as fomites
Agents of airborne transmission?
- Varicella virus
- Measles virus
- Coronavirus
- Mycobacterium tuberculosis
Describe handwashing?
- Placing the hands under water and using friction with or without soap.
- 15-second scrub removes the majority of transient, surface flora
- Hand gels and rubs can be used in place of handwashing
Describe waterless hand hygiene?
- Preferred agents for routine hand hygiene when hands are not visibly soiled
- Effectively kills most microbes but do not remove dirt or debris
- Ineffective against nonenveloped agents such as norovirus andC. difficilespores
Standard precautions in disease prevention?
Aims?
involve the use of barriers
e.g. gloves, gowns, masks, goggles, and face shields—as needed
- Aims to prevent transmission of microbes associated with contact with blood and body fluids
