Based on the response to my email about the flu vaccination, people raised a few questions and I had one of my own. The first question is about viral shedding. Your first thought is probably “What’s that?”

Viral shedding is the period of time when you’re infected and can transmit the flu virus to someone else—it’s when you’re contagious. The question from the reader wondered whether someone who has been vaccinated will still be contagious to others if they’re infected with the flu. The answer is yes; being vaccinated against this year’s flu will not inhibit your ability to infect others if you get the flu. Remember, some people who are vaccinated will still get the flu.

The problem with the flu is that you can be shedding the virus while you still feel fine. You can be infectious up to a day before the onset of symptoms and up to 24 hours past the end of the fever. The difference may be related to the form of flu, whether influenza A or B. However, the data are not completely clear.

The point is that you should still be cautious if you begin to feel symptoms, whether vaccinated or not. While you can’t catch the flu from the vaccination because the virus used is dead, you might still get the flu. The goal is to protect others. Speaking of others, we’ll talk about herd immunity on Thursday.

What are you prepared to do today?

Dr. Chet

Reference: https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flu.html