The first Covid-19 vaccine tested in the U.S. increased up people's immune systems just the way scientists had hoped, researchers said.

Washington: The first Covid-19 vaccine tested in the U.S. increased up people's immune systems just the way scientists had hoped, researchers said.

“No matter how you slice this, this is good news,” Dr. Anthony Fauci, the U.S. government's top infectious disease expert said.

Anthony FauciThe experimental vaccine, developed by Fauci's colleagues at the National Institutes of Health and Moderna Inc., will start its most important step around July 27.

There's no guarantee but the government hopes to have results around the end of the year.

Fauci said final testing will include older adults, as well as people with chronic health conditions that make them more vulnerable to the virus.

Nearly two dozen possible Covid-19 vaccines are in various stages of testing around the world. Candidates from China and Britain's Oxford University also are entering final testing stages.

CoronavirusThe 30,000-person study will mark the world's largest study of a potential Covid-19 vaccine so far.

Around the world, governments are investing in stockpiles of hundreds of millions of doses of the different candidates, in hopes of speedily starting inoculations if any are proven to work.