Cyclic variations in the occurrence of pneumonia and influenza mortality may reflect:
seasonal variations in cases of influenza.
the fact that influenza is a disappearing disorder.
long-term changes in mortality trends.
both A and B
Cyclic variations in the occurrence of pneumonia and influenza mortality may reflect:
seasonal variations in cases of influenza.
the fact that influenza is a disappearing disorder.
long-term changes in mortality trends.
both A and B