Influenza (Green 12/4/2019)

Thanks Dr. Gary Green, for an awesome rapid fire tour de force through influenza-- seasonal and otherwise-- its virology, natural history, pharmaceuticals, complications, with a fascinating dip into medical history with a little future-telling. Plus he handed out Kit Kats. Cannot beat it. If you missed it, here’s the video recording: starts about nine minutes in, Gary Green FLU Grand Rounds

Here’s a few things to know:

• Flu is here (we admitted two new influenza cases in the last 48 hours). 
• It’s an early start to the season in California, a mix of Flu A and B (B usually follows A but this year, they are double dating). 
• As of 11/16, there have been 13 deaths in California (all in people over 50).
• And now for a little history:
• The first recognized and recorded influenza pandemic was in 1510
• The 1918 Spanish flu actually started in Fort Riley, Kansas!
• Influenza caused More than 10x fatalities than WWI
• 28% of the US population was affected, 675,000 people died in US
• S/Sx
• Influenza like illness (ILI): notable for its abrupt onset, fever/chills, headache, myalgias and malaise, cough. GI symptoms (nausea, vomiting, diarrhea) and interestingly leg pain (myalgias) fairly common in kiddos
• As you know, flu is spread by sneezing, coughing (droplets can travel 6 feet), even talking (talking droplets are smaller and can hang around longer)
• Incubation period is 1-4 days (usually 2), average length of shedding 4.8 days (but can be shed for up to 19 days in immunosuppressed) 
• Depending on the year, 12,000-56,000 people die each year in the US of flu, 140,000-700,000 are hospitalized
• Most affected by flu are youngest (<1y) AND oldest (>65y) but every year perfectly healthy 30 and 40 year olds also DIE of the flu
• The vector for flu: CHILDREN. Children tend to get less sick, run around and spread it
• High risk conditions for severe influenza: age (<5, >65), pregnancy (up to 2 weeks postpartum), Native Americans and Alaskan natives.
• Also those with underlying medical conditions: asthma, COPD, neurologic disorders, ESRD, HIV, heart disease, cirrhosis, and morbid obesity (to name a few)
• Complications of influenza: 
• Primary viral pneumonia
• Secondary bacterial pneumonia: in one study, 11-35% of laboratory confirmed flu had bacterial co-secondary infection/CAP (strep 35%) staph (28%)
• Myositis, rhabdo (more common in kids)
• Cardiac: known association with acute MI in elderly within 7d of infection
• Aseptic meningitis (common! High fever, headache)
• Seasonal flu vaccine: ranges in effectiveness 10-60%, average about 50% effective
• Vaccination is the only intervention we have that REDUCES mortality (by 36%), also reduces risk of post-flu PNA by 17%, 
• Meds have not been shown to reduce mortality: Neuramidase inhibitor current standard of care with <48 hours of symptoms (oseltamivir 75mg PO BIDx 5 days). Now also zanamavir (inhaled, contraindicated COPD/Asthma) and IV Peramavir (though maybe not as effective as oseltamivir).
• Did you get your flu shot yet?