Despite considerable progress in research, a vaccine against the deadly SARS virus will take at least two years to produce, the U.N. health agency says.
"We must be ready to manage a possible resurgence of SARS through the control measures that work -- surveillance, early diagnosis, hospital infection control, contact tracing and international reporting," Lee Jong-wook, director-general of the World Health Organization, said Wednesday.
"Research must continue to determine if, how and how soon a vaccine will add to these existing control measures."
Lee was speaking following a conference of 50 researchers from more than 15 countries who considered the information available for the development of a vaccine and how the virus causes disease in humans.
First detected in China a year ago, Severe Acute Respiratory Syndrome spread to Hong Kong as well as to other parts of Asia and to Canada. It sickened more than 8,000 people and killed 774 last (northern hemisphere) winter and spring, according to WHO figures.
The global outbreak was declared over in July, but scientists fear that there could be another outbreak of the disease over the next few months.
WHO said that if SARS reappears, a vaccine could be produced within two years. If there is no new outbreak, it likely will take four or five years.
"However urgent the need for a vaccine, safety and quality must never be compromised," said Dr. Marie-Paule Kieny, head of the WHO's Initiative for Vaccine Research.
"But, it is clear the sooner we can develop a vaccine against SARS the better prepared we will be in case the disease reappears."
Some of the usual procedures for vaccine development may need to be changed for SARS, WHO said.
In particular, it may be necessary to license SARS vaccines even if no trial has been carried out to show how effective they are in humans.