Vaccine Schedules Gregory Hussey Vaccines for Africa Initiative - - PowerPoint PPT Presentation

Vaccine Schedules

Gregory Hussey Vaccines for Africa Initiative Institute of Infectious Diseases University of Cape Town

www.vacfa.com gregory.hussey@uct.ac.za

Expanded Programme on Immunization (EPI)

• Established 1974
• Built on advances in smallpox eradication
• Objective to raise childhood immunization

coverage.

• Basic vaccines – BCG, OPV, DTP, Measles.
• Strategy – routine immunization services.

Five operational components of EPI

Service delivery

Vaccine supply & quality Logistics Advocacy & communication

Surveillance

Supporting elements of the EPI

Elements exist at national, regional and district level Political and social commitment Actions of development partners

$1.37 $1.26 $1.40 $2.23 $2.39 $11.58 $11.04 $11.11 $27.16 $35.78 $0.00 $5.00 $10.00 $15.00 $20.00 $25.00 $30.00 $35.00 $40.00 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 USD Year

Estimated Lowest Price* to purchase a full course of vaccines for a child up to 1 year of age, according to WHO Universal Recommendations^

2) Hepatitis B 3) Hib 4) PCV 5) Rotavirus

Cost of following WHO recommendations is rising!

6) PCV Purchased by GAVI

1) Traditional EPI

MSF – The right shot

Vaccine costs for SA

• BCG
• OPV
• Measles
• Hep B
• Hib

/DTP/IPV

• Rota
• Pneumo
• HPV
• TOTAL

R4 R2 R8 R16 R408 R160 R510 R700 R1808

What is “routine immunization”

• No standard definition

– Means different things to different people – Regional and agency differences

• The sum of human and logistical activities or

events to ensure the regular delivery & uptake of vaccines & the monitoring and evaluation of their impact

What is “routine immunization”

• Implies the “regular” delivery, i.e. a known

schedule of EPI vaccines

• Part of a larger plan
• Not time limited
• Goal to provide needed vaccines to all

eligible persons and to successive birth cohorts

Routine vs Supplemental immunization Routine: Day to day immunisation according to country immunisation schedule Supplemental: In addition to/adding to routine/ strengthening routine immunisation coverage

Service delivery

• Vertical service with centralized leadership

and management, supervision, training and M&E

• Part of comprehensive primary care with or

without central procurement, training and M&E

Specific strategies for delivery

• Fixed clinics – periodic or continuous
• Outreach – fixed site or door-to-door visits
• Mobile teams usually from a fixed clinic
• Supplementary immunization activities such

as campaigns

Factors that may influence seroprotection rates following vaccination

• Age – elderly and very young / premature infants
• Immune deficiency
• Genetic factors
• Dose of vaccine
• Migrants
• Nutritional status – malnourished / vitamin A

deficient

• Route of administration – id vs im

http://www.who.int/immunization/policy/imm unization_tables/en/

Basic schedule – DTP based

Vaccination of Premature infants

• The immune response to vaccination is a function of postnatal

rather than gestational age. Transplacentally acquired maternal antibody is present in lower concentrations in prems and persists for shorter period.

• Infants born prematurely, regardless of birth weight, should be

vaccinated at the same chronological age and according to the same schedule and precautions as full-term infants and children.

• Exception: HBV - Decreased seroconversion rates might occur

among certain preterm infants with birth weights of less than 2,000 g after administration of hepatitis B vaccine at birth. DON’T COUNT HBV1 DOSE.

• Several studies suggest that the incidence of adverse events after

vaccination of preterm infants is the same as or lower than that of full-term infants vaccinated at the same chronological age.

Vaccination of ill infants

• Mild illness is not a contra-indication for

vaccination.

• Postponing vaccination in children with minor

febrile or afebrile illness constitutes a missed

• pportunity to protect a child from disease,

can contribute to outbreaks of vaccine- preventable disease.

• Vaccination usually is deferred in persons who

have moderate or severe illness.

Conclusion

• Immunisation is an evolving science
• Vaccination schedules are not set in stone.
• Given the differences in epidemiology, health

infrastructure and resources, it will be difficult to develop a single immunisation schedule for all countries.

• Optimising schedules for new vaccines could reduce

cost and streamline their integration with other vaccines.

• WHO has recommended vaccination schedules; they

are very useful, particularly in low- and middle-income countries.

Seroconversion

• Seroconversion is the development of detectable specific antibodies to

microorganisms in the blood serum as a result of infection or

• immunization. Serology (the testing for antibodies) is used to determine

antibody positivity. Prior to seroconversion, the blood test is seronegative for the antibody; after seroconversion, the blood test is seropositive for the antibody.

• Seroconversion usually means that you have developed immunity to the

specific infection. HOWEVER

• seroconversion may indicate current infection–and transmissibility of a

pathogen–eg, HIV-1–seroconversion to p24 and/or p41 antibody production or HBV–seroconversion to surface antibody-HBsAb or e antibody–HBeAb production.

Seroprotection

• the level of antibody titers equal or above

which you are regarded as being protected from disease.

• seroprotection rates refer to the % of infants

with antibody titers equal or above the assay cut-off were set such that subjects who had titers above the cut off could be considered protected from disease.

Correlate of protection

• Correlates of immunity/protection to a virus or other infectious pathogen are

measurable signs that a person (or other potential host) is immune, in the sense of being protected against becoming infected and/or developing disease.

• For many viruses, antibodies serve as a correlate of immunity. So for example,

pregnant women are routinely screened in the UK for rubella antibodies to confirm their immunity to this infection which can cause serious congenital abnormalities.

• In contrast for HIV, TB, HPV, Malaria, the simple presence of antibodies is clearly not

a correlate of immunity/protection since infected individuals develop antibodies without being protected against disease.

• The fact that the correlates of immunity/protection remain unclear is a significant

barrier to HIV vaccine research. There is evidence that some highly exposed individuals can develop resistance to HIV infection, suggesting that immunity and therefore a vaccine is possible. However, without knowing the correlates of immunity, scientists cannot know exactly what sort of immune response a vaccine would need to stimulate, and the only method of assessing vaccine effectiveness will be through large phase III trials with clinical outcomes (i.e. infection and/or disease, not just laboratory markers).

Vaccines and Related Biological Products Advisory Committee March 7, 2001 FDA Briefing Document for SmithKline Beecham Biologicals’ DTPa-HepB-IPV Vaccine Antigen Serological Method Endpoints** DTPa-HepB-IPV antigens Diphtheria Toxoid (D) ELISA 0.1 IU/mL Tetanus Toxoid (T) ELISA 0.1 IU/mL Pertussis Toxoid (PT) ELISA 5 EL.U/mL Filamentous Haemagglutinin (FHA) ELISA 5 EL.U/mL Pertactin (PRN) ELISA 5 EL.U/mL Hepatitis B surface antigen (HBs) RIA 10 mIU/mL Poliovirus types 1, 2, 3 (IPV) Cell culture Neutralization 1/8 Haemophilus influenzae type b (Hib) ELISA* 0.15 and 1.0 mcg/mL