Be careful of articles that identify something as the biggest category. It's usually a trick to mislead people. Which category is biggest depends on how you choose your categories. If a person is malnourished, and that causes them to suffer worse from the flu so they die, was their death due to malnourishment or disease or a virus or the flu or the 2020 flu? Or what if there were two types of malnourishment classified separately (say lack of protein and lack of vitamins)? Suddenly neither of them would likely be number 1 because they'd both be smaller categories. The article doesn't explain any of that so it's safe to assume that it's misinformation even if technically correct in some way.