Bit of humor, to break the tension.

My father likes vodka tonics. He asked me how many he would have to drink a day to get the anti-viral benefits associated with Quinine. I looked up the ingredients and informed him that he only needed to drink about 6 gallons of tonic water per day, now add the vodka. His joking reply, guess I better get busy.

Here is the wiki it used to calculate the amount,

In the United States, the US Food and Drug Administration (FDA) limits the quinine content in tonic water to 83 ppm[3] (83 mg per liter if calculated by mass), while the daily therapeutic dose of quinine is in the range of 500–1000 mg,[4] and 10 mg/kg every eight hours for effective malaria prevention (2100 mg daily for a 70 kg adult).[5] It is often recommended as a relief for leg cramps, but medical research suggests some care is needed in monitoring doses.[6] Because of quinine's risks, the FDA cautions consumers against using "off-label" quinine drugs to treat leg cramps.[7]