I have not seen anything that promises to work anywhere near as well as my zapper when it comes to influenza or other viral illness.
For bacterial infections, it is faster and immediately more effective than any antibiotic that I have tried. The advntage that antibiotics have is that they linger in the body for a day or so. When you turn the zapper off, the effects are gone.
I do disagree with 2-tuff though. While not an immediate threat, viri can and do mutate. This has happened many times in history. The swine flu, Hong Kong flu of the 60's were avian flu viri that mutated enough to become virulent to pigs which then jumped to humans.