(Reuters) – Johnson & Johnson said on Wednesday it would start human trials of its potential COVID-19 vaccine in the second half of July, two months earlier than planned, as drugmakers race to develop a shot for the deadly respiratory disease.

The company has already signed deals with the U.S. government to create enough manufacturing capacity to produce more than 1 billion doses of its vaccine through 2021.

There are currently no approved treatments or vaccines for COVID-19, the illness caused by the new coronavirus that has killed more than 400,000 people globally.

J&J’s study will test the vaccine against a placebo and assess the shot’s safety and immune response in 1,045 healthy people aged 18 to 55 years, as well as those 65 years and older. The trial will take place in the United States and Belgium.

U.S. biotech Moderna Inc is at the forefront of COVID-19 vaccine development and has started testing its candidate in a mid-stage trial that will enroll 600 patients. The company expects to begin late-stage trials in July.

AstraZeneca, Sanofi, Pfizer and GlaxoSmithKline are all at various stages of development of their vaccine candidates.

There are currently about 10 coronavirus vaccines being tested in humans and experts have predicted that a safe and effective vaccine could take 12 to 18 months from the start of development.

(Reporting by Saumya Sibi Joseph in Bengaluru; Editing by Saumyadeb Chakrabarty)