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VII Curso de Vacunologia Ciro de Quadros para America Latina
11 al 15 de Diciembre Buenos Aires, Argentina
Introducción de nuevas vacunas:
medición de impacto y efectividad
Dr. Lúcia Helena De Oliveira
Asesora Regional de Nuevas Vacunas
Unidad de Inmunizaciones/FGL
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Topicos principales
• Conceptos de
Eficacia
Efectividad
Impacto
• Estudios de efectividad e impacto
Título de la presentación
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Eficacia
• Vaccine efficacy is commonly defined as the direct effect of a vaccine measured in pre- licensure randomized clinical trials, where vaccination is allocated under optimal
conditions
Hanquet G, et al. Vaccine effects and impact of vaccination programmes in post-licensure studies. Vaccine (2013), http://dx.doi.org/10.1016/j.vaccine.2013.07.006
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Efectividad
• Vaccine (direct) effectiveness is estimated by
comparing vaccinated and unvaccinated individuals exposed to the same vaccination programme.
• Most sources define vaccine effectiveness as a measure of protection attributable to a vaccine administered under field conditions to a given population.
• It is measured by observational post-licensure studies
Hanquet G, et al. Vaccine effects and impact of vaccination programmes in post- licensure studies. Vaccine (2013), http://dx.doi.org/10.1016/j.vaccine.2013.07.006
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Impacto
• The impact of a vaccination programme, defined here as the population prevented fraction when exposure is the
programme, is measured by comparing populations with and without a vaccination programme, most commonly the same population before and after vaccination.
• These designs are based on a number of assumptions for valid inference. In particular, they assume that vaccinees and non- vaccinees do not differ in terms of susceptibility and exposure to the disease or in ascertainment of vaccination and disease status.
Hanquet G, et al. Vaccine effects and impact of vaccination programmes in post- licensure studies. Vaccine (2013), http://dx.doi.org/10.1016/j.vaccine.2013.07.006
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Impacto
• In pre and post-vaccination design, the population is assumed to have similar
baseline transmission, case detection and
reporting, risk factors and medical practices in both periods.
• These principles are frequently violated in post-licensure studies.
Hanquet G, et al. Vaccine effects and impact of vaccination programmes in post- licensure studies. Vaccine (2013), http://dx.doi.org/10.1016/j.vaccine.2013.07.006
Tipos de efectos de vacunas y diseños de estudios
Medición de efectividad e impacto:
El caso de la vacuna de rotavirus y neumococo conjugada en LAC
Título de la presentación 8
L.H. De Oliveira et al. / Vaccine 31S (2013) C99– C108
Monthly ratio of rotavirus diarrhea to total diarrhea cases.
On the y axis, the proportion of rotavirus diarrhea cases is shown for the different follow-up years shown on the x axis.
Estudos de impacto da
vacina de RVA, Panamá e Nicarágua.
Panamá
(1):
22% em 2007 e 37% em 2008
Nicarágua
(2): 23% durante o
período de sazonalidade de RVA crianças <12 meses quando
comparado a 6% em crianças de 12-59 meses
Introdução de la vacuna em 2006 Diminuição das
diarreias em general:
(1)Molto,Y et al.The Ped Inf Dis J.vol 30,num.1, Jan 2011.
(2)Orozco, M.et al. JID 2009:200-Supp1.
2007 2008 2009
Esperado Observado
Brasil: despois da introdução de la vacina ocorreram menos 130,000 admissões por diarreia nos menores de 5 anos,
2007-2009*
*Carmo, G. et al. Plos Medicine, April 2011, Vol 8, Issue 4.
Ministry of Health of Brazil, CDC and PAHO
Brasil: depois da la introdução da vacina ocorreram menos 1500 mortes por diarreia em menores de 5 anos,
2007-2009*
2007 2008 2009
Esperado
Observado
*Carmo,G. et al. Plos Medicine, April 2011, Vol 8, Issue 4.
Ministry of Health of Brazil, CDC and PAHO.
Effectiveness of the 13-valent pneumococcal conjugate vaccine in preventing invasive pneumococcal disease in children aged 7-59 months.
A matched case-control study
De Oliveira et al.14
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Revision Sistematica y meta-analysis
Conclusiones
Effectiveness and impact measures provided by post-licensure observational studies are becoming crucial for decision-making.
Observational studies measure different effects of the vaccine and the
vaccination programme, depending mostly on which population groups are being compared.
Vaccine effectiveness: measure of the direct effect of a vaccine on vaccinated individuals.
The impact of a vaccination programme refers to the overall effect of a
vaccination programme (or its population prevented fraction) and is measured by comparing one population in which the vaccination is implemented to a reference population without vaccination programme.
Conclusiones
Although observational designs are prone to biases, they remain to date the most feasible and acceptable methods to quantify vaccine-related effects. They are the only
designs able to detect longer-term changes in the population at large, such as vaccine-induced disease replacement and herd immunity.
When reporting post-licensure vaccine studies, researchers should specify which effects they measure, in which
population, and systematically address possible biases
and confounders.
Muchas gracias!!!
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