Times to key events in the course of Zika infection and their implications for surveillance

Added August 8, 2017

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Surveillance can do little to reduce the risk of Zika contaminated blood donations. High incidence areas may consider PCR testing for donated blood to ensure safety for use in pregnant women.

Research to determine the time it takes for Zika Virus to appear in the blood after infection and the time for antibody seroconversion is vital to quantify the risk to blood supplies, and develop efficient strategies for protection. A systematic review and pooled analysis was performed to estimate the incubation period, time to seroconversion, and length 30 of shedding of Zika virus in infected populations. Twenty-five cases were included in the review. Median incubation period of Zika virus infection was estimated to be 5.9 days (95% CI: 4.4-7.6); 95% of people developing symptoms do so by 11.1 days post-infection (95% CI: 7.6-18.0). On average seroconversion occurs 9.0 days (95% CI, 7.0-11.6) after infection, and virus is detectable in blood for 9.9 days (95% CI: 6.8-21.4). The baseline (no screening) risk of a Zika infected blood donation increases by approximately 1 in 10,000 for every 1 per 100,000 person-days increase in Zika incidence. Symptom based screening reduces this by 7% (RR 0.93, 95% CI 0.86-0.99), and antibody screening by 29% (RR 0.71, 95% CI: 0.28-0.88). Risk of bias was not assessed.