Thursday, 30 January 2014

H7N9 snapdate: charts bonanza...[UPDATED]

Now that I see Mike Coston's tweet and blog post, it's fairly safe to assume that all the cases have been announced for today (tonight/morning, my time). I should be working on my seminar, but I'm doing this instead. Apparently that makes me a "data wonk"...a definition I just learned tonight from CDC Director Dr Tom Frieden....
Click on image to enlarge.
Precise dates for the last 3-4 weeks may change as (a) cases are still
being announced retrospectively and (b) the WHO updates lag
a little behind as they collate and add in valuable additional data.
So let's update a few H7N9 charts.

Firstly, weekly confirmed cases, and case accumulation over both waves of H7N9 infections. Don't be fooled by that terminal dip though-it will rise as cases are sorted by onset date that are yet to be advised in WHO's disease outbreak notifications.


Click on image to enlarge.
Secondly, is the case fatality chart. This one's reliability is particularly "wobbly" at present since there are as many as 21 deaths that cannot be linked to a case announcement at present. 
FluTrackers has a nice turn-of-phrase; "We've lost visibility" on these numbers in China. Equally, identifying cases that have been discharged from hospital relies entirely on the provincial media releases; Google translate really excels at nonsensical sentences with these. A total of 66 deaths (if that is the number currently) produce a proportion of fatal cases (PFC) of 25% or the 226 total cases; trending back up again.


Click on image to enlarge.
Thirdly, we have the updated chart for region of H7N9 acquisition. This shows Zhejiang, after a quiet day this week, continuing its steep upward trend, accompanied by a resurgent Guangdong and a staggering yet rising Fujian and Jiangsu provinces, Shanghai municipality and some occasional cases in Beijing and Hunan province.


Click on image to enlarge.
Fourthly, and lastly for this post anyway, the H7N9 case with age charts. 

Some of the detail required for reading these 3 charts can be found at my previous post using this figure.

Suffice to say that the flurry of new H7N9 cases in southern and eastern China has highlighted the age bias once again; few cases under 20-years of age, many cases >60-years. 

I do wonder what a prospective RT-PCR study of specimens from mild respiratory illnesses and from asymptomatic community members in the <20-year age group would yield. Possibly more positives that are not being "seen" with the more immediate hospitalizations and severe illnesses. 

I also wonder how the intensive care capacity is coping with all these critical and severe cases. Of course H7N9 is far from a prominent influenza in many parts of the world right now. 

At the end of 2013, H3N2 and H1N1 were predominating among China's seasonal influenza infections. H7N9 is just an added and worrisome burden; yet it is thankfully a burden that is not transmitting among humans in an efficient and sustained manner.