Vitamin C seems to strengthen our immune system especially if it is a megadose, over 6000mg a day. (But it should be be under 11900mg a day at maximum according to wikipedia) I’m taking 2 tablets(2000mg) per meal. It affects positively to our body but is discharged after a few hours through urine without harmful effects, so it seems to be safe. Some doctors from youtube say it could be beneficial against corona virus whether you believe or not…!