Why antibody testing is crucial to coronavirus fight

"Corona" is Spanish for "crown" — a reference to the crown-like spikes on their surface.

Those spikes are the key to how the virus infects people — and scientists think neutralizing them could be a path to immunity.

When coronavirus enters the body, spiked proteins on its surface, called antigens, attach to healthy cells and turn them into "factories."

Graphics by Andrew Wong

These factories begin mass-producing more coronavirus cells — sometimes millions of them.

This is where antibodies come in. They are how our immune system fights these antigens.

Antibodies are Y-shaped proteins whose tips are designed to interlock with specific antigens.

The tips on coronavirus antibodies envelop the spikes, preventing the virus from hijacking healthy cells.

And the body remembers antibodies, which means it could potentially more readily fight off the virus once it's produced them. So tests are key.

To test this immunity, scientists draw blood and inject coronavirus into the sample.

If the blood neutralizes the coronavirus, the antibodies were present and effective. This person could be less likely to get infected — or to infect others.

Over time, when enough of the population has antibodies, the virus might not be able to reproduce and spread this strain on the level it has been.

This is herd immunity — the path back to normal life.