"It is reported that about half of the humans who contract avian influenza in Vietnam do not die"
Ascorbic Acid Role in Containment of the World Avian Flu Pandemic
http://journals.sagepub.com/doi/abs/10.3181/00379727-232-2320847

---

"Although vitamin C status varies with time, geography and population groups, these figures indicate that low vitamin C levels are not rare, even though frank scurvy is. Thus, if low vitamin C levels increase the risk of pneumonia, this effect may be of wide interest globally. The possible effect of vitamin C on the risk of respiratory infections in physically stressed people is also highly relevant.

Immediate practical conclusions cannot be drawn from the studies discussed in this essay. The findings suggesting benefit of vitamin C against lung infections in restricted population groups are important from the public health point of view and motivate further studies. Nevertheless, the effects of vitamin C on respiratory infections are also important at the level of fundamental concepts, because they indicate that the effects of vitamin C are not limited to preventing and treating scurvy."
Vitamin C may affect lung infections
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2099400/

---

Ananchrnous case where selenium deficit mice survived flu better than mice with selenium. 1) Did the virus mutate in the low selenium animals? Not testing the virus on other animals after if had passed though a living mice leaves this uncertain. 2) There should have been a control group being fed selenium without being given flu. If they died too, maybe their selenium wasn't pure or as low a dose as they thought.
Selenium deficiency induced an altered immune response and increased survival following influenza A/Puerto Rico/8/34 infection.
https://www.ncbi.nlm.nih.gov/pubmed/17327475/