WNV vaccine(Laboratorios Hipra)

West Nile virus (WNV) is the leading cause of arboviral disease in the United States and is associated with significant morbidity and mortality. A previous analysis found that a vaccination program targeting persons aged ≥60 years was more cost-effective than universal vaccination, but costs remained high.

We used a mathematical Markov model to evaluate cost-effectiveness of an age- and incidence-based WNV vaccination program. We grouped states and large counties (≥100 000 persons aged ≥60 years) by median annual WNV incidence rates from 2004 to 2017 for persons aged ≥60 years. We defined WNV incidence thresholds, in increments of 0.5 cases per 100 000 persons ≥60 years. We calculated potential cost per WNV vaccine-prevented case and per quality adjusted life-years (QALYs) saved.

Vaccinating persons aged ≥60 years in states with an annual incidence of WNV neuroinvasive disease of ≥0.5 per 100 000 resulted in approximately half the cost per health outcome averted compared to vaccinating persons aged ≥60 years in the contiguous United States. This approach could potentially prevent 37% of all neuroinvasive disease cases and 63% of WNV-related deaths nationally. Employing such a threshold at a county level further improved cost-effectiveness ratios while preventing 19% and 30% of WNV-related neuroinvasive disease cases and deaths, respectively.

An age- and incidence-based WNV vaccination program could be a more cost-effective strategy than an age-based program while still having a substantial impact on lowering WNV-related morbidity and mortality.

The purpose of this study was to establish if peak serum amyloid A (SAA) concentrations can be used to determine an appropriate immune response to a vaccine containing West Nile Virus (WNV) antigen. A pilot study with 20 clinically healthy horses was performed to identify peak SAA concentration postvaccination with a commercial multivalent WNV vaccine. Blood was collected for SAA at 0, 24, 48, 72, 96, 168 hours postvaccination. Serum for WNV serum neutralization antibody testing was obtained immediately prior to and 30 days postvaccination. An additional 40 horses underwent the study protocol, but with SAA measurements acquired at 0-hours and 72-hours postvaccination. Ninety percent of the population had an increase in SAA in response to WNV vaccination, though no significant correlation was identified between SAA peak and antibody titer fold changes. WNV antibody titer fold changes between pre- and post-vaccination revealed 57% of horses had increased fold changes, 30% had no fold changes and 13% had negative fold changes. There was a negative correlation between age and SAA response (P = .0008). The main conclusions were SAA response postvaccination against WNV does not appear to mirror antibody response. Age appears to significantly affect SAA response. Further, vaccination with WNV antigen may not consistently induce a positive increase in WNV antibodies.