Start with a free account for 12 free CME credits. Already a subscriber? Sign in.
Chapter 1

Flu: Test and Treat. Or Not.

AK Kalantari DO and Rob Orman, MD
Sign in or subscribe to listen

No me gusta!

The flash player was unable to start. If you have a flash blocker then try unblocking the flash content - it should be visible below.

How one approaches and manages influenza is part science and part preferred practice style.  Today’s podcast presents AK’s interpretation of the literature and how she manages patients during a shift. As you will see, AK is a testing and treatment minimalist.

To view chapter written summaries, you need to subscribe.

Sign up today for full access to all episodes.

James M. -

Excellent summary, thank you

gmete -

This was a good and timely podcast. One question I had for Ak is about treating to prevent viral shredding and communicability to others. I wonder if there is any evidence about doing this especially in a person with a positive flu who is insistent on getting on a plane the next day. This just happened to me in the ER the other day. Pt was positive, looked clinically stable but I treated her since I knew she was going to expose others. Good idea? Bad?

AK K. -

Great question and sorry for the delay in answering. I had to do some homework and then decided to completely nerd out and write a little summary of what I read. It took be a bit longer than expected.

With regard to spreading the illness, 30% of transmission cases occur in the household1 and most of those are from kids.2 Once one individual gets infected, the risk of transmission to others within the household is 10%-20%. A good bit of the literature utilizes viral load as a proxy for infectivity and duration of viral shedding as a proxy for infectiousness but these relationships haven’t been validated or confirmed in natural settings.1

Tsang et al compared the relationship between viral load/shedding and infectivity of PCR confirmed influenza A in 386 Hong Kong households and found although there was no statistical significance between viral load and infectivity, there was dose dependent response. The estimated index cases in the high and medium shedding groups were estimated to have 21% and 44% higher infectivity compared to those in the lower viral shedding group.1 That makes sense and this study was probably not powered well enough to demonstrate the statistical change we have all come to love with data analysis. So I think we can comfortably say, higher viral load & shedding equals more spreading of the illness.

With regard to neuraminidase inhibitors and decreased viral shedding, we have a couple useful studies. Fry et al evaluated the efficacy of treatment with oseltamivir to reduce illness duration and viral shedding, to monitor for adverse events associated with oseltamivir in this setting, and to establish whether such treatment initiated 48 h or longer after illness onset had any effectiveness to reduce illness duration and viral shedding. It was a double-blind, randomized, placebo control trial conducted the crowded, low income community of Dhaka, Bangladesh. 1190 individuals with PCR confirmed influenza were enrolled in the study: 794 with less than 48 hours since symptom onset, 396 with greater than 48 hours since symptom onset. They were then randomized into a placebo group vs an oseltamavir group. Compared with the placebo group, a significant reduction in virus detection by PCR, virus isolation and virus titration was recorded in the oseltamivir group. This reduction was even more pronounced in the influenza A patients.1,3

Another paper published in JAMA in 2001 evaluated the effectiveness of oseltamivir in preventing influenza transmission to household contacts within households who had one person with PCR confirmed influenza. The study enrolled household contacts from homes that had an index case of PCR confirmed influenza. These were a handful of inclusion and exclusion criteria for these household contacts but one of the main inclusion criteria were that they could not have any degree of viral shedding at the time of enrollment. The contacts were then randomized to a 7 day course of placebo vs oseltamivir. Investigators then monitored for the development of influenza in the contacts. 24/200 in the placebo group developed influenza verses 2/205 in the oseltamivir group. There was significantly reduced viral shedding in those of the treatment arm.4

So, the answer to your question. There are no studies that look at influenza transmission in airplanes but we know a few things: we know there are plenty of cooties exchanged during flights, the degree of viral shedding is proportional to infectivity and that oseltamivir reduces viral shedding. With all of that being said, I don’t think it is unreasonable to treat influenza in those individuals who will be in close proximity of other individuals especially if those at risk of exposure also happen to be at risk for high mortality or morbidity with influenza.

1. Tsang TK, Fang VJ, Chan K-H, et al. Individual correlates of infectivity of influenza A virus infections in households. PloS one. 2016;11(5):e0154418.
2. Whitley RJ. The role of oseltamivir in the treatment and prevention of influenza in children. Expert opinion on drug metabolism & toxicology. 2007;3(5):755-767.
3. Fry AM, Goswami D, Nahar K, et al. Efficacy of oseltamivir treatment started within 5 days of symptom onset to reduce influenza illness duration and virus shedding in an urban setting in Bangladesh: a randomised placebo-controlled trial. The Lancet infectious diseases. 2014;14(2):109-118.
4. Welliver R, Monto AS, Carewicz O, et al. Effectiveness of oseltamivir in preventing influenza in household contacts: a randomized controlled trial. Jama. 2001;285(6):748-754.

To join the conversation, you need to subscribe.

Sign up today for full access to all episodes and to join the conversation.

To earn CME for this chapter, you need to subscribe.

Sign up today for full access to all episodes and earn CME.

2.25 AMA PRA Category 1 Credits™ certified by Hippo Education (2019)