In a milestone moment in the race for a coronavirus vaccine, the first results in humans showed Moderna’s vaccine candidate led to antibody responses in a handful of healthy volunteers.

The Massachusetts biotech on Monday described the immune-system responses to the vaccine from this first, small study that was primarily focused on safety. The results don’t yet show whether the vaccine would prevent people from being infected with the novel coronavirus.

Finding an effective coronavirus vaccine has become a global priority in ending the pandemic. US government leaders have put forward the ambitious timeline to have one by the end of 2020. It typically takes several years to develop a vaccine.