Impact of age-specific immunity on the timing and burden of the next Zika virus outbreak.

Michel J Counotte,Julien Riou,Nicola Low,Christian L Althaus,Marilia Sá Carvalho

doi:10.1371/journal.pntd.0007978

Michel J Counotte, Julien Riou + Show 3 more

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https://doi.org/10.1371/journal.pntd.0007978

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Abstract

The 2015–2017 epidemics of Zika virus (ZIKV) in the Americas caused widespread infection, followed by protective immunity. The timing and burden of the next Zika virus outbreak remains unclear. We used an agent-based model to simulate the dynamics of age-specific immunity to ZIKV, and predict the future age-specific risk using data from Managua, Nicaragua. We also investigated the potential impact of a ZIKV vaccine. Assuming lifelong immunity, the risk of a ZIKV outbreak will remain low until 2035 and rise above 50% in 2047. The imbalance in age-specific immunity implies that people in the 15–29 age range will be at highest risk of infection during the next ZIKV outbreak, increasing the expected number of congenital abnormalities. ZIKV vaccine development and licensure are urgent to attain the maximum benefit in reducing the population-level risk of infection and the risk of adverse congenital outcomes. This urgency increases if immunity is not lifelong.

Highlights

Zika virus (ZIKV) is a flavivirus, which is transmitted primarily by mosquitoes of the genus Aedes
A continuous endemic circulation of ZIKV in the region would increase the probability of an outbreak early on and lead to more stochasticity. In this mathematical modelling study, we show that a new ZIKV outbreak in Nicaragua would affect proportionally more women in the young reproductive age range (15–29 years) than the general population, owing to the age-dependent infection pattern and population renewal
The sizeable ZIKV outbreak in Nicaragua will likely not occur before 2035 but the probability of outbreaks will increase

Summary

Introduction

Zika virus (ZIKV) is a flavivirus, which is transmitted primarily by mosquitoes of the genus Aedes. ZIKV probably became established in Aedes aegypti mosquitoes in the Americas between 2013-2014, [5, 6] and spread rapidly across the continent. WHO stated, in September 2016, that ZIKV in pregnancy was the most likely cause of the clusters of microcephaly, and other adverse congenital outcomes [8, 9]. By the beginning of 2018, over 220,000 confirmed cases of ZIKV infection had been reported from Latin America and the Caribbean [12], which is estimated to be only 1.02% (± 0.93%) of the total number of cases, based on mathematical modelling studies [6]

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