Definition: In this task, you are given an abstract of article. Your task is to generate title for this article. Preferred titles are under thirty words.
Input: West Nile virus (WNV) is a major cause of mosquito-borne illness in the United States. Human disease ranges from mild febrile illness to severe fatal neurologic infection. Adults aged >60 years are more susceptible to neuroinvasive disease accompanied by a high mortality rate or long-lasting neurologic sequelae. A chimeric live attenuated West Nile virus vaccine, rWN/DEN4&Dgr;30, was shown to be safe and immunogenic in healthy adults aged 18–50 years. This study evaluated rWN/DEN4&Dgr;30 in flavivirus-naive adults aged 50–65 years and found it to be safe and immunogenic. Outbreaks of WNV infection tend to be unpredictable, and a safe and effective vaccine will be an important public health tool.

A Live Attenuated Chimeric West Nile Virus Vaccine, rWN/DEN4&Dgr;30, Is Well Tolerated and Immunogenic in Flavivirus-Naive Older Adult Volunteers