Cost-benefit analyses of supplementary measles immunisation in the highly immunized population of New Zealand.

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Vaccine. 2017 Sep 5;35(37):4913-4922. doi: 10.1016/j.vaccine.2017.07.077. Epub 2017 Aug 10.

Cost-benefit analyses of supplementary measles immunisation in the highly immunized population of New Zealand.

Hayman DTS¹ Marshall JC² French NP² Carpenter TE³ Roberts MG⁴ Kiedrzynski T⁵.

(m)EpiLab Infectious Diseases Research Centre Massey University Palmerston North 4442 New Zealand. Electronic address: D.T.S.Hayman@massey.ac.nz.

(m)EpiLab Infectious Diseases Research Centre Massey University Palmerston North 4442 New Zealand.

EpiCentre Infectious Diseases Research Centre Massey University Palmerston North 4442 New Zealand.

Infectious Diseases Research Centre Institute of Natural & Mathematical Sciences New Zealand Institute for Advanced Study Massey University Private Bag 102 904 North Shore Mail Centre Auckland New Zealand.

Ministry of Health Wellington New Zealand.

Abstract

As endemic measles is eliminated from countries through increased immunisation the economic benefits of enhanced immunisation programs may come into question. New Zealand has suffered from outbreaks after measles introductions from abroad and we use it as a model system to understand the benefits of catch up immunisation in highly immunised populations. We provide cost-benefit analyses for measles supplementary immunisation in New Zealand. We model outbreaks based on estimates of the basic reproduction number in the vaccinated population (R_v the number of secondary infections in a partially immunised population) based on the number of immunologically-naïve people at district and national levels considering both pre- and post-catch up vaccination scenarios. Our analyses suggest that measles R_v often includes or exceeds one (0.18-3.92) despite high levels of population immunity. We calculate the cost of the first 187 confirmed and probable measles cases in 2014 to be over NZ$1 million (∼US$864200) due to earnings lost case management and hospitalization costs. The benefit-cost ratio analyses suggest additional vaccination beyond routine childhood immunisation is economically efficient. Supplemental vaccination-related costs are required to exceed approximately US$66 to US$1877 per person depending on different scenarios before supplemental vaccination is economically inefficient. Thus our analysis suggests additional immunisation beyond childhood programs to target naïve individuals is economically beneficial even when childhood immunisation rates are high.