Following a briefing, my sister (Paediatric Oncologist with the Teenage Cancer Trust) has given this advice to my parents:

2gm Vit C a day in divided doses
25mcg of Vit D a day

If symptoms appear:

1gm Vit C
3mg Zinc
50mg elderberry extract hourly

She has also told them to isolate themselves from human contact as much as possible.

"Y mae dafad ddu ym mhob praidd"
1972 4/4, 1981 MGBGT, 1984 FLHT1340, 1980 XLH1000, 1990 ZX10