CRP and infection: In addition, when comparing patients of the same age with a single infection and viral co-infection, patients aged 0.1 to 24 months with co-infection had higher levels of CRP, and those aged 0.1 to 24 and 24.1 to 60 months had higher levels of D-Dimer than those with a single infection (p < 0.05; Figure 6), while only patients aged 0.1 to 24 months with a single infection had higher urea levels than those with co-infection (p < 0.05; Figure 6).