Slight uptick in flu activity in Week 16

[JimO]

In most states, one or more of the indicators (%ILI, %positive, hospitalizations) have increased for the first time in more than a month. Activity is still very low, but there seems to be an increase in flu indicators in the 0-4 and 4-19 age groups, in particular, which is a bit troubling. In most prior seasons, these indicators continued to decline and/or leveled off at low levels until fall. If this is the beginning of an increasing trend, it could be the start of a summer wave, like we saw in 2009.

I was also expecting P&I deaths to drop off sharply last week, but it stayed at around 8%. With the epidemic threshold decreasing each week this time of year, that means there was a larger departure from the epidemic threshold than last week. The Pacific region is well above average at over 11%.

We need to remain alert.

 

[JimO]

Re: Slight uptick in flu activity in Week 14

Re: Slight uptick in flu activity in Week 14

I thought I'd post some examples. In Georgia, the number of ILI visits and %ILI in 0-4 yr olds has increased.





Even in Florida, where flu levels have been relatively normal, there has been a subtle increase in %ILI in 0-19 yr olds. This corresponds closely to the jump seen about the same time in the spring of 2009, which was not reflected last spring.



More to come...

 

[JimO]

Re: Slight uptick in flu activity in Week 14

Re: Slight uptick in flu activity in Week 14

http://www.azdhs.gov/phs/oids/epi/flu/pdf/influenza/influenza_2010-11_wk14.pdf

No data were reported on isolates detected in Week 13; however, the results from Week 14 indicate a slight increase in the number of positive specimens from Week 12, the percent positive continues to be high, and the number of pH1N1 positive tests has increased notably since Week 12, relative to the seasonal strains. Also, at 41% of the positive specimens, this was the highest percentage of pH1N1 in Arizona this season.



The %ILI has increased, for the first time in six weeks, and is back above the epidemic threshold.

 

[JimO]

Re: Slight uptick in flu activity in Week 14

Re: Slight uptick in flu activity in Week 14

http://www.doh.wa.gov/EHSPHL/Epidemiology/CD/fluupdate.pdf

Washington is puzzling, because although most of the indicators suggest the flu is waning, the hospitalization rate in 0-4 and >65 age groups is still rising sharply. These graphs show data from Spokane.

 

[Missouriwatcher]

Re: Slight uptick in flu activity in Week 14

Re: Slight uptick in flu activity in Week 14

Fluview week 14: "In recent weeks the proportion of influenza B viruses identified nationally and in some regions has been increasing and in week 14 two of the 10 regions (Regions 1 and 2) reported more influenza B viruses than influenza A viruses."

 

[JimO]

Re: Slight uptick in flu activity in Week 14

Re: Slight uptick in flu activity in Week 14

That explains the demographics of hospitalizations in Spokane and the isolates chart supports that as well.

Isn't it an odd time of year for Flu B to be increasing?

Fluview week 14: "In recent weeks the proportion of influenza B viruses identified nationally and in some regions has been increasing and in week 14 two of the 10 regions (Regions 1 and 2) reported more influenza B viruses than influenza A viruses."

 

[JimO]

Re: Slight uptick in flu activity in Week 14

Re: Slight uptick in flu activity in Week 14

http://doh.sd.gov/Flu/PDF/Week14.pdf

Here is another subtle example. Based on the %ILI and the Isolates data, flu activity in South Dakota has peaked and has dropped to near baseline levels.



However, hospitalizations more than doubled from 7 (Week 13) to 16 (Week 14). Perhaps this is just an anomaly, but there are quite a few such anomalies from Week 14.

 

[JimO]

Re: Slight uptick in flu activity in Week 14

Re: Slight uptick in flu activity in Week 14

http://dhmh.maryland.gov/fluwatch/

From Maryland's Week 14 report that came out today:

 

[Missouriwatcher]

Re: Slight uptick in flu activity in Week 14

Re: Slight uptick in flu activity in Week 14

Looking at limited data from ISDS Distribute showing:

Slight increase in ED ILI for Regions 3, 8, 9, as well as AR, VT, CT and Tulsa. There has also been a steady increase over several weeks in RI and MA, according to graphs. (week ending 4/16)
http://isdsdistribute.org/

 

[JimO]

Re: Slight uptick in flu activity in Week 16

Even more so than two weeks ago, the vast majority of indicators suggest that the flu season is over. In fact, there really isn't much evidence related to %ILI or isolates data to explain the continued elevated percent P&I deaths that have persisted. However, some indicators in states for each of the examples below do suggest a potential increase in flu activity. But, other indicators in those same states suggest the opposite. Some key states (NM, PA, AL) where there have been indications of increased flu over the past two weeks have not updated since Week 14 (PA) or Week 15 (NM and AL).

Here is the Isolates chart from Week 15 for Alabama



The hospitalizations chart from Week 15 for South Carolina



This is the isolates chart from Week 16 for Arizona



The %ILI chart from Week 16 for Maryland



The isolates chart from Week 16 for Minnesota



The %ILI chart from Week 16 for Texas



The %ILI chart from Week 16 for Washington