The NHS has taken action to remove false Twitter accounts that have been spreading "misleading" information about the coronavirus outbreak.
One account, falsely set up in the name of a hospital in Andover, urged the Hampshire town to "move into lockdown" amid an "influx of patients".
The NHS said it had intervened to have the account shut down.
It said it would ensure official NHS accounts on Twitter, Instagram and Facebook were properly flagged.
The NHS said it had not traced the owner of the "Andover hospital" account, which falsely warned of the "influx of patients" displaying coronavirus symptoms.
NHS chief executive Sir Simon Stevens said: "The NHS has already been battling coronavirus fake news, from working to take down false Twitter accounts to speaking out against misleading treatments being promoted by homeopaths online."
He said the organisation was working with social media platforms to verify or "blue tick" more than 800 official NHS accounts.
The NHS said it had worked with Google to display official websites more prominently in results when people searched for coronavirus.
It said in future some searches would also trigger pop-up "Knowledge Panels" containing advice about Covid-19 and other health issues.
On Monday, the government announced a specialist unit had been set up to counter disinformation about the coronavirus outbreak.
Health Secretary Matt Hancock said: "Today's actions are another important step so members of the public can access reliable, accurate health information."