Tests that can tell if you're immune to the coronavirus are on the way. Here are the companies racing to bring them to the US healthcare system.

• With the novel coronavirus still confining people to their homes in large swaths of the country, all eyes are on the burgeoning market for immunity tests.
• Called serology kits, they look for antibodies that indicate immunity to the virus. Having immunity could eventually let people return to work.
• Regulators eased the approval process in March, prompting a handful of companies to make serology tests in-house or sign deals with drugmakers overseas to bring them to US customers.
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With millions of Americans trapped in their homes and a record number filing for unemployment, demand for tests that can tell if people are immune to the novel coronavirus is skyrocketing.

Unlike a test that diagnoses the virus itself, immunity tests can identify if people have been exposed to it in the past, according to the Centers for Disease Control and Prevention. With a finger prick of blood, the tests, called serology kits, detect the immune response by measuring antibodies the body developed to fight off the coronavirus.

Experts have said that large-scale immunity testing is necessary for a safe return to normal life. People could find out if they're protected against the virus and possibly go back to work. By the same token, healthcare workers could use serology tests to return to the front lines of coronavirus-related care after exposure to sick patients.

On March 16, the Food and Drug Administration relaxed approval restrictions for immunity kits, prompting a handful of firms to start development internally or clinch deals with drugmakers overseas.

Here are the companies working to bring serology testing to the US, according to company announcements and data compiled by the Center for Health Security at Johns Hopkins.