A less than ideal match may result in reduced vaccine effectiveness against the variant viruses, but it still can provide enough protection to prevent or lessen illness severity and prevent flu-related complications.

Accumulating evidence indicates that patients with comorbid depression and anxiety tend to have greater illness severity and a lower treatment response than those with either disorder alone.

Previous studies had produced similar differences, but have been generally discounted as based on such differences as illness severity, insurance coverage, or patient preference.

The researchers are now collaborating with drug company scientists who are trying to develop new treatments for influenza, using the two cytokines as indicators of illness severity and therefore the effectiveness of the remedy being tested.

Dr. Niculescu and his team are also developing blood biomarker tests to assess illness severity and measure response to treatment.

Nancy Andreasen has argued for an association between antipsychotic drugs and smaller grey matter volumes independent of illness severity.

Recent attempts to define QoL have resulted in the development of a functional definition that is measurable, evaluable over time, and readily applied to patients over a wide range of illness severity.

This systematic review only included studies that looked for an independent effect of delirium (i.e., after accounting for other associations with poor outcomes, for example co-morbidity or illness severity).

Risk factors for suicide among people with schizophrenia include a history of previous suicide attempts, the degree of illness severity, comorbid depression or post-psychotic depression, social isolation, and male gender.

Some studies show that there is no link between expressed emotion and first episode psychosis, illness severity, age of onset, and illness length.