“Why am I still sick?”
That’s a common question I hear after someone has been infected with influenza and started on therapy. Most of us associate our times of illness with some common bacterial infections: sinusitis, pneumonia, ear or skin infections. When we get infected with these bacterial pathogens they tend to stay localized to the area affected and not to invade different parts of the body all at once. These infections can cause massive inflammation but are focused at a single site. Additional bacteria only accumulate if the original organism has the resources to make more. This is why bacterial infections tend to start slowly and build. It takes time to grow more organisms.
Appropriate antibiotic therapy usually causes the bacterial invaders to be actively destroyed. That is, most antibiotics kill bacteria thereby reducing the number of invaders left in the body. Although some antibiotics only slow the replication of bacteria. People often feel dramatically better after about 24-48 hrs of antibiotic therapy because the number of invading organisms declines rapidly.
Viral invaders, of which influenza is a beast, follow a different set of rules. These invaders are known for their ability to cause havoc in several different parts of the body at once. Remember the last cold you had? You had a runny nose, a sore throat, and an annoying cough. Three parts of your respiratory track were infected and therefore you had three types of symptoms. Compare this to strep throat where only the throat hurts but there is no runny nose or cough.
Additionally, viral invaders are masters at sabotage. They invade your own cells and overtake them. They will insert their own genetic structure into the manufacturing systems of the cells. Instead of making normal healthy proteins useful for your body you are now making more virions (virus particles). You are now making more of the invading army. To kill off these viral invaders the body must sacrifice the cells infected by programming their early death.
When you get started on an antiviral medication, like Tamiflu for influenza, it hinders production of new virions. The virion particle number peaks and doesn’t increase at the exponential rate it had been doing. Antiviral therapy does not, however, kill off any virions already made. Your body has to do that and that takes time. The body must develop antibodies that recognize the specific threat and attack it. This process often takes the better part of two weeks to occur under the best of circumstances. Unfortunately, there are many different types of viral infections but only a few of them have good antiviral therapy available. Thankfully, most viral infections are annoyances and are no real threat to our health. For some of the more severe infections, like influenza and herpes (especially when it infects the brain), we have some relatively good therapies if they are initiated at the right time.
So it is easy to see why viral infections tend to linger causing symptoms even after antiviral therapy has begun and why early therapy for influenza makes such a difference in symptom intensity and duration.