The first large-scale trials of a vaccine against the Zika virus is at least 18 months away, dpa quoted a senior World Health Organization (WHO) official as saying Friday in Geneva. Two vaccines that are being developed by the US National Insitutes for Health and by the Indian company Bharat Biotech are currently the most advanced among the 15 Zika vaccine projects that are underway in several countries, said deputy WHO chief Marie-Paule Kieny. "Diagnostic tools will be developed much more quickly than vaccines," she told reporters. Tools for quick diagnostic tests would be available within weeks, she said.