The way I understand it, it helps the body's immune system to be ready to launch a response, by way of heightened production of something called Interferon alpha/beta ( A cytokine ), so it probably prevents severe Interferon II flood ( the cytokine storm ), Interferon I that normally binds to neighboring cells and starts the exponential growth of the alarm of invasion, is prevented by 2019-nCov

Interferon I binds to Lyphocyte Interferon II and this is when the immune system officially gets the chemical message cells are under attack ( Body's immune response gets the message from the cellular immune response, just two molecules binding )

ascorbic acid will increase lymphocyte production, but there still needs to be a messenger molecule from the infected cells.....and this virus stops them from putting it out

2019-nCov is actually a variable pH virus, and not dependent on specific pH like Influenza is ( Low pH needed to enter cells, this weakens cell membranes ), so varying blood pH with vitamin is likely not going to have an effect on the ability of the virus to gain entry to cells ( Influenza uses a different type of receptor )

so....vitamin C will at least help keep your immune system at the ready