Georgia ILI Curve

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February 22, 2020: Flu-like illness peaked in Georgia in late December, then peaked a second time in mid-February. Just like the rest of the country, Georgia is experiencing a second peak of flu activity, this time due to influenza A. We have now had 2-3 weeks of decreasing flu activity in Georgia. Flu season is winding down; flu should be largely gone from Georgia by mid- to late March.

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We provide weekly updates from the Georgia Division of Public Health during the flu season, roughly November through March of each year. There is generally a one week lag between data collection and availability to the public. The red triangles indicate the percentage of visits to outpatient health facilities by patients with fever plus either cough or sore throat (Influenza-Like Illness or ILI). A person with ILI does NOT necessarily have the flu. There are many viruses in circulation that mimic the flu and cause similar symptoms. But when ILI cases start to climb in the winter, this is a good indication that flu itself is on the rise as well.

For the complete weekly influenza update from the Georgia Division of Public Health please click here.

How is this curve constructed?       Each week a group of “sentinel providers” around the country reports to CDC on how many of their patients in emergency departments and clinics have illnesses that match the CDC case definition for “influenza-like illness”, or ILI. ILI is defined as fever PLUS either cough or sore throat that cannot be attributed to another cause such as Strep throat (i.e. Strep throat is NOT an ILI). This data is collected at CDC and posted.

What does the curve mean?     The ILI curve does not tell us the total number of people with flu, it tells us what proportion of patients around the country have an illness like the flu. ILI occurs at a low background rate of 1-2%  throughout the year, even when flu is not circulating. Years of experience has shown that when the ILI curve peaks in the winter, it closely correlates with actual influenza activity as determined by more tedious and expensive viral cultures. Thus, the ILI curve provides a convenient way to track the progress of an influenza outbreak. During the winter (i.e., flu season), most people with ILI actually do have the flu. During the summer and autumn months, patients with ILI almost invariably are infected with other respiratory viruses that are not influenza. The summer of 2009 was a major exception to this rule, reflecting the spread of pandemic flu due to 2009 H1N1 during the US summer months.

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Past Updates

February 10, 2020: Flu-like illness peaked in Georgia in late December, but is now increasing once again. Just like the rest of the country, Georgia is experiencing a second peak of flu activity, this time due to influenza A. This will likely continue to rise over the next 1-3 weeks as Flu A replaces Flu B here and around the US.

January 24, 2020: Flu appears to be on the decline in Georgia after peaking in December, but there may be more to come. In the Augusta area, we had almost all flu B in December, but about 4 weeks ago flu B was largely replaced by flu A, which is by far the most common isolate in the CSRA. Don’t be surprised if the Georgia curve goes back up in a second peak.

December 28, 2019: Influenza-like illness is rising sharply in Georgia and appears to be heading for a peak. This is very early for peak flu activity in the US. More ominously, influenza A is being detected in more and more patients, both in the CSRA and nationally. If these trends continue, we may be in for a double peak in flu this year, the first from flu B and the second from flu A.

December 16, 2019: Flu activity continues to be high in Georgia as of mid-December. While it may appear to be dipping slightly, don’t be fooled. The season only began 4-5 weeks ago. Generally we can expect influenza to continue circulating for 6-10 weeks in a region. And so far we have seen primarily Flu B, an unusual occurrence early in the season. If we have our usual degree of Flu A, we may actually get two peaks this year. Stay tuned.

November 23, 2019: Georgia has been above the epidemic threshold for the last four weeks, indicating that Georgia is a few weeks ahead of most of the nation. The national ILI curve (see main page G-LINE) just passed the epidemic threshold in the past week. It appears that the seasonal flu epidemic is starting in the Southeast, with Georgia joining a chain of states from South Carolina to Texas as the beginning of the national epidemic.

November 15, 2019: Flu activity in Georgia is low but increasing. We have just passed the epidemic threshold (dotted line) that indicates the start of the 2019 flu season.

November 9, 2019: This graph shows visits for Influenza-Like Illness (ILI) in Georgia for the week ending November 9, 2019. The red triangles tracing the 2019-2020 season are now consistently above the epidemic threshold (dotted line). Georgia has entered the flu season, but it is still very early. There is a lot of flu still ahead of us.