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Childhood Vaccines: Why we vaccinate, when we vaccinate. ACIC 9 th Annual Conference Marian Michaels MD, MPH Professor of Pediatrics Children’s Hospital of Pittsburgh Division of Pediatric Infectious Diseases. 2014 AAP Vaccine Schedule 0-18 years. Immunizations.
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Childhood Vaccines:Why we vaccinate, when we vaccinate ACIC 9th Annual Conference Marian Michaels MD, MPH Professor of Pediatrics Children’s Hospital of Pittsburgh Division of Pediatric Infectious Diseases
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
Change in Vaccine Preventable Diseases Immunization Action Coalition 12/13
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
Vaccinate to protect the person at risk when they are at risk:Example – HiB Meningitis
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 • Don’t respond to polysaccharide (either as vaccine or natural disease until > 2 years of age • First vaccine (1985) polysaccharide • Variable efficacy < 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
Before vaccination ~ 20,000 cases/year with ~ 1000 deaths/year Polysaccharide vaccine -1985 Conjugate vaccine -1987 Invasive HiB Disease, USA 1990-2007 3 cases of HiB at CHP in 2013 (all unvaccinated) Year *Rate per 100,000 children <5 years of age (CDC data)
S pneumoniae • Pre-vaccine era • 17,000 invasive cases S pneumoniae < 5 years • 700 cases meningitis • 200 deaths • Similar to HiB < 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
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)
Vaccinate to protect the person at risk: Polio during the 1950’s ~ 20, 000 cases paralytic polio/year
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
Poliovirus • Enterovirus • Fecal – oral spread • Replicates locally • Secretory Ab • Viremia +/- CNS • Humoral Ab
Polio • > 90% asymptomatic • < 10% symptoms: • Fever, pharyngitis, malaise • Anorexia, mylagias • CNS symptoms develop • 1% of children • 10% adolescents or adults
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
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
Salk vaccine 1955 Poliomyelitis—United States, 1950-2007 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
Sabin - OPV • Practically perfect • Inexpensive, easy to administer • Mimics natural infection • IgA and IgG antibody • Herd immunity • Susceptible individuals protected
Polio • Global eradication occurring • Last wild type polio • U.S.A. 1979 • Americas 1991 • Western hemisphere “polio-free” 1994
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
Comparison of Vaccine Types In era of no wild type polio, 6-8 cases VAPP too many Polio Vaccine schedule altered 2000 to eIPV
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
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)
Whooping cough/ Pertussis • Bacteria Bordetella pertussis • Outbreaks every 2-5 year cycles • Very easy to transmit • >90% 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 Children’s due to pertussis
PertussisThree phases • Catarrhal phase – seems like a simple cold • Can transmit to others • Treatment can work • Paroxysmal phase – cough, whoop, emesis • Can transmit • Treatment doesn’t work but prevents transmission • Convalescent phase- 100 day cough • Exacerbations • Adults and older children = reservoir
Whole Cell Pertussis Vaccine • Introduced in 1940’s • Adverse reactions occurred • Non-serious reactions common • Low grade fever in ~45 % of infants • Fever > 101 in 16% • Moderate to severe fussiness or pain in ~ 40% • More serious reactions very rare
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 wasn’t a big deal
Pertussis Vaccine • Large epidemiologic studies comparing DT to DPT (>15000 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 infant’s first cause of a fever • Also a time when many seizure syndromes show up naturally
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. <5% DTaP • Mod/severe Pain 40% DTwP vs. 4-11% DTaP
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
Vaccinate an Available Population to Protect Them Later • Example of HPV, Hepatitis B • Controversial for parents • “My child isn’t at risk”
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
Human Papillomavirus (HPV) • DNA virus- causes warts: > 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 > 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
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 26 • 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
HPV: Combatting Myths • Pre-licensure studies: blinded:control • > 20,000 women and > 4,000 males • Post licensure non controlled VAERS report • > 60 million HPV4 and > 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
On line Vaccine Resources • Center for Disease Control and Prevention • http://www.cdc.gov/vaccines/ • Immunization action coalition • http://www.immunize.org/aboutus/ • Children’s Hosp of Phil. vaccine service • http://www.chop.edu/service/vaccine-education-center/