SAN ANTONIO – This year’s flu season started earlier than it typically does and tens of thousands of Texans have already fallen ill.
As cases continue to rise, Dr. Jason Bowling, University Health hospital epidemiologist and associate professor with UT Health SA, answered some commonly asked questions about influenza and the flu vaccine.
Q: What is the difference between Flu A and Flu B?
Dr. Bowling: There are some differences in the molecular structure, but you can get really sick with either strain. The main thing to recognize is that every flu season actually represents several different strains of influenza circulating, which means people can get infected with different strains. It also highlights why natural immunity is not sufficient to protect from infection from a different strain.
Q: Is this year’s flu shot effective against the strains that we’re seeing?
Dr. Bowling: It’s still early in the season, but the CDC samples circulating isolates to see how close a match they are to the vaccine strains and the early results are showing that the influenza isolates selected for the vaccine appear to be a good match This can change even during the course of the influenza season but it is a promising start.
Q: If you get the flu before you get the flu shot, should you still get the shot? How long should you wait?
Dr. Bowling: You should still get the flu vaccine even if you’ve had the flu because there are several strains circulating. That’s why there are four different strains in this year’s quadrivalent flu shot. Natural immunity does not provide enough protection to keep you from getting sick with a different strain in the same flu season. As for timing, it can vary according to the individual, but it’s generally recommended that you wait until you have completely recovered from the acute influenza infection and your immune system is close to baseline so that you’ll get a sufficient immune response to the vaccine. For most people that’s at least two weeks, but it may be better if you wait about four weeks.
Q: If you’ve been exposed to the flu and haven’t had your shot, should you get it immediately or wait?
Dr. Bowling: Exposure is not a good reason to wait. A flu vaccine is not going to prevent you from getting sick if you truly were exposed, but many people are getting exposed right now without knowing it. There’s a lot of flu virus circulating, so if you are not already acutely ill it’s better to get the flu vaccine right now, even if you’ve been exposed, because you’re probably going to get exposed again soon.
Q: Do you recommend that children take Tamiflu?
Dr. Bowling: The biggest benefit is for children with severe disease. If children are admitted to the hospital for influenza they should definitely get Tamiflu, and I would consider it for children who are at high risk for progressing to severe disease, such as a child that has an underlying medical condition. If oseltamivir (Tamiflu) is started within 48 hours of symptom onset, it can reduce duration of symptoms by about 24 hours (1 day). If it’s an otherwise healthy child, Tamiflu probably won’t make much difference.
Q: If you have Flu A could you get Flu B at the same time or one right after the other?
Dr. Bowling: It is possible to get viral coinfections with two strains of flu, but usually we see people infected with flu and a non-flu virus at the same time. And you could also get one right after the other.
Q: How long after you show symptoms are you contagious?
Dr. Bowling: How long you are contagious after first showing symptoms can vary – children and immunocompromised people are going to shed virus longer – but most people are considered contagious to others for about 5-7 days after symptom onset with influenza.