Professor Sharon Peacock, director of the National Infection Service at Public Health England, revealed on Wednesday that millions of such a test have been ordered and could be used "in the near future".
They would show whether an individual had antibodies for COVID-19 which, if they did, would mean they could return to work if they were not showing symptoms.
Evidence suggests people cannot catch coronavirus twice in quick succession, if they have already been infected and recovered, the government has said.