Childhood Vaccines: Why we vaccinate, when we vaccinate

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Childhood VaccinesWhy we vaccinate, when we
vaccinate

• ACIC 9th Annual Conference
• Marian Michaels MD, MPH
• Professor of Pediatrics
• Childrens Hospital of Pittsburgh
• Division of Pediatric Infectious Diseases

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2014 AAP Vaccine Schedule 0-18 years
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Immunizations

• Aside from improved sanitation nothing has done
  as much to improve the health of children as
  immunizations
• Effective vaccine
• Induces a strong long lasting protective
  responsive in a safe fashion
• Decreases death and disease from the natural
  infection

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Change in Vaccine Preventable Diseases
Immunization Action Coalition 12/13
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Childhood VaccinationWhy we vaccinate when we
vaccinate

• Vaccinate individuals at risk
• Vaccinate a population to protect others
• Vaccinate an available population to protect them
  later
• As we discuss examples will address rationale for
  using particular types of vaccines

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Vaccinate to protect the person at risk when they
are at riskExample HiB Meningitis
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Invasive HiB by Age Pre Vaccine
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Haemophilus influenza B (HiB)

• This bacteria caused most of the meningitis in
  children between 2 and 56 months of age
• Highest risk for severe disease is 2-12 mo
• Ab against polysaccharide capsule is protective
• Dont respond to polysaccharide (either as
  vaccine or natural disease until gt 2 years of age
• First vaccine (1985) polysaccharide
• Variable efficacy lt 2 years of age
• Too little too late to impact on group at risk
  for disease
• Newer vaccines (1987) conjugated the
  polysaccharide to a carrier Ag so T cell
  dependent to be effective in children under 1
  year of age

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• Invasive HiB Disease, USA 1990-2007

Before vaccination 20,000 cases/year with
1000 deaths/year Polysaccharide vaccine
-1985 Conjugate vaccine -1987
3 cases of HiB at CHP in 2013 (all unvaccinated)
Year
Rate per 100,000 children lt5 years of age (CDC
data)
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S pneumoniae

• Pre-vaccine era
• 17,000 invasive cases S pneumoniae lt 5 years
• 700 cases meningitis
• 200 deaths
• Similar to HiB lt 2 years of age highest risk
• Antibody to polysaccharide offers protection
• Unlike HiB many different serotypes
• 7 associated with most pediatric invasive dz.
• 2000- first conjugate vaccine PCV 7
• Types 4, 9V, 14, 19F, 23F, 18C, and 6B

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S pneumoniae vaccine

• After initial great success started to see
  increases in invasive disease with non PCV7
  strain
• 2010 added 1, 3, 5, 6A, 7F, 19A (PCV13)

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Vaccinate to protect the person at risk Polio
during the 1950s 20, 000 cases paralytic
polio/year
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Poliomyelitis Historical Events

• 3700 BC Earliest recorded history-Egyptian
  Mummy
• 1793 Underwood described unequivocal cases of
  polio
• 1949 Propagation of poliovirus in human
  embryonic tissue
• 1955 Inactivated vaccine licensed (Salk)
• 1961 Live attenuated vaccine licensed (Sabin)
• 1962 US nationwide mass vaccination program

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Poliovirus

• Enterovirus
• Fecal oral spread
• Replicates locally
• Secretory Ab
• Viremia /- CNS
• Humoral Ab

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Polio

• gt 90 asymptomatic
• lt 10 symptoms
• Fever, pharyngitis, malaise
• Anorexia, mylagias
• CNS symptoms develop
• 1 of children
• 10 adolescents or adults

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IPV

• Salk vaccine, 1955
• Formalin killed, Types 1,2,3
• Neutralizing Ab in 95
• Protects individual from polio
• Shedding of wild type polio can still occurs if
  infected
• Enhanced version licensed 1982

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OPV

• Sabin vaccine, 1962
• Attenuated, live oral Types 1,2,3
• Replicates like w. polio
• Secretory and neutralizing Ab
• No shedding of wild type poliovirus
• Vaccine virus shed in stool
• Immunizes contact
• Contact-associated VAPP

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• PoliomyelitisUnited States, 1950-2007

Salk vaccine 1955
Western Hemisphere Polio free- 1994 So why
continue to vaccinate for polio Parts of Africa,
Asia never free Fall 2013-13 cases Syria (last
seen 1999) Virus also found in Israel
Oral Sabin vaccine
Last indigenous case
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Sabin - OPV

• Practically perfect
• Inexpensive, easy to administer
• Mimics natural infection
• IgA and IgG antibody
• Herd immunity
• Susceptible individuals protected

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Polio

• Global eradication occurring
• Last wild type polio
• U.S.A. 1979
• Americas 1991
• Western hemisphere polio-free 1994

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Vaccine-Associated Polio

• 6-10 cases every year
• 50 vaccinee 50 contact
• Usually after 1st dose
• Unique susceptibility of host
• Wild type polio absent
• eIPV introduced 1982

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Comparison of Vaccine Types
Vaccine Type OPV eIPV
Prevents polio Yes Yes
Neutralizing Ab Yes Yes
Secretory Ab Yes No
Good immunity Yes Yes
Herd immunity Yes No
VAPP Yes No
In era of no wild type polio, 6-8 cases VAPP too
many Polio Vaccine schedule altered 2000 to eIPV
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Vaccinate to Protect and at Risk Population
Congenital Rubella

• Mild disease
• Infection during pregnancy
• Miscarriage
• Fetal death
• Congenital rubella syndrome

Vaccinate children to prevent disease in
pregnant women to protect the unborn baby
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Sunday Rubella CampaignPittsburgh, PAMay 17,
1970

• Over 2,000 volunteers
• 106 sites (mostly schools)
• 130 hypospray jet injectors
• 190,845 children immunized
• (58 of susceptibles 1-12 yr)

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Vaccinate to Protect and at Risk Population
Whooping Cough
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Whooping cough/ Pertussis

• Bacteria Bordetella pertussis
• Outbreaks every 2-5 year cycles
• Very easy to transmit
• gt90 attack rate in susceptible household
  contacts
• Infants can have very severe disease
• Pneumonia, periods of inability to breathe,
  seizures, brain damage, death
• Nov 2013 Aug 2014 two newborns died at
  Childrens due to pertussis

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PertussisThree phases

• Catarrhal phase seems like a simple cold
• Can transmit to others
• Treatment can work
• Paroxysmal phase cough, whoop, emesis
• Can transmit
• Treatment doesnt work but prevents transmission
• Convalescent phase- 100 day cough
• Exacerbations
• Adults and older children reservoir

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Whole Cell Pertussis Vaccine

• Introduced in 1940s
• Adverse reactions occurred
• Non-serious reactions common
• Low grade fever in 45 of infants
• Fever gt 101 in 16
• Moderate to severe fussiness or pain in 40
• More serious reactions very rare

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Pertussis Vaccine

• People who were against the vaccine claimed that
  the vaccine caused
• SIDS, Seizures, Brain Damage
• They also believed that
• Decrease in pertussis due to improved sanitation
• Believed natural disease wasnt a big deal

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Pertussis Vaccine

• Large epidemiologic studies comparing DT to DPT
  (gt15000 children studied)
• No true association of vaccine with severe
  disease symptoms
• Temporal association
• Vaccine is given at 2, 4, 6 months
• This is often an infants first cause of a fever
• Also a time when many seizure syndromes show up
  naturally

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Japanese outbreak of whooping cough 1976-1981
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Rationale for developing the acellular pertussis
vaccine

• Concern about adverse effects with DTwP
• Public perception of severe risk
• Improvements possible
• Decrease reaction to vaccine
• Large studies conducted to show that rates of
  fever and fussiness and pain decreased
• Low grade fever 45 DTwP vs 16-30 DTaP
• High fever 16 DTwP vs. lt5 DTaP
• Mod/severe Pain 40 DTwP vs. 4-11 DTaP

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Acellular pertussis vaccine

• Desire to protect those too young to be
  vaccinated by vaccinating others cocooning
• Tdap adolescents and adults
• Repeat towards end of each pregnancy to give
  passive Ab to infant (and immunity to mother)
• Likely will use in future for booster as well for
  all adults

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Vaccinate an Available Population to Protect Them
Later

• Example of HPV, Hepatitis B
• Controversial for parents
• My child isnt at risk

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Hepatitis B vaccine

• Given during infancy
• Prevents much of maternal transmission
• Asia uses it alone without HBIG
• Maternity hospitals are considering not giving
  due to cost
• Step backwards
• When shortage occurred Hepatitis transmission
• Works well in young age group
• Protects those who will develop risks later
• Not just Drug users
• Policemen, Firemen, Nurses, Cardiac surgeons
• Accident victims requiring emergency transfusions

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Human Papillomavirus (HPV)

• DNA virus- causes warts gt 100 types
• Genital HPV is most common STD in US
• Types 6 and 11 cause 90 genital warts
• Types 16, 18 cause 70 cervical cancers
• HPV associated gt 70 oropharyngeal CA
• Type 16 associated most prominently
• 2006 quadrivalent HPV vaccine approved for girls
  and young women bivalent vaccine approved for
  girls in 2009
• 2009 HPV4 approved for males as well
• 2011 HPV4 recommended for males

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HPV recommendations

• Not beneficial after wild type infection
• Desire vaccine before sexual debut
• ACIP recommends age 11-12
• HPV 4 or HPV 2 for girls
• HPV 4 for boys
• Can start as young as 9 years, Catch up till age
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• Poor uptake by community
• a lack of knowledge,
• a belief that the vaccine was not needed,
• concerns about vaccine safety or side effects
• the vaccine not being recommended by their
  provider

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HPV Combatting Myths

• Pre-licensure studies blindedcontrol
• gt 20,000 women and gt 4,000 males
• Post licensure non controlled VAERS report
• gt 60 million HPV4 and gt 700,000 HPV2 doses
• Most AE non SAE
• Systemic nausea, dizziness, headache, syncope,
  urticaria
• Local symptoms injection-site redness, swelling,
  and induration
• No association found with autoimmune disease,
  Guillain Barre syndrome, stroke

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On line Vaccine Resources

• Center for Disease Control and Prevention
• http//www.cdc.gov/vaccines/
• Immunization action coalition
• http//www.immunize.org/aboutus/
• Childrens Hosp of Phil. vaccine service
• http//www.chop.edu/service/vaccine-education-cent
  er/