Could these monkeys hold the answers to controlling the novel coronavirus?
Researchers in Thailand began testing a new vaccine on them on Saturday.
Officials said it followed successful trials in mice.
The country's minsiter for science, research and innovation said researchers hoped to have a 'clearer outcome' of the vaccine's effectiveness by September.
The hope is that it will be in production by next year.
More than 100 potential vaccines for COVID-19, the disease caused by the novel coronavirus, are being developed.
Several are in clinical trials - but the World Health Organisation warned in April a vaccine would take at least 12 months.
Thailand was the first country outside China to detect a case of the coronavirus in January.
The government says it wants to be one of the first to have a vaccine ready for use.