CDC's week 40 FluView, covering the week ending October 10, 2026, put national clinical lab positivity at 5.0 percent. One week earlier it was 3.9 percent. Five HHS regions are rising, the virus is almost entirely A(H1N1)pdm09, and the season is barely two weeks old by CDC's own calendar. If your clinic, school district or senior living group is still running on last winter's leftover rapid flu tests, this is the week to count what is on the shelf and order the gap. Keystone stocks Flu A/B and Flu/COVID combo rapid tests in Edina with next-day delivery across the Upper Midwest and Plains.
What the week 40 numbers actually say
The headline figure is the jump, not the level. CDC still describes activity as low. The trend is what buyers need to act on.
| Indicator | Week 39 (ending Oct 3) | Week 40 (ending Oct 10) |
|---|---|---|
| Clinical lab positivity | 3.9 percent (2,070 of 53,137 specimens) | 5.0 percent (2,270 of 45,331 specimens) |
| HHS regions with increases of 0.5 points or more | 1, 2, 3, 4, 7, 8, 9 | 4, 6, 7, 8, 9 |
| A(H1N1)pdm09 share of subtyped influenza A | 98.4 percent (125 of 127) | 96.4 percent (242 of 251) |
| Outpatient ILI visits | Below baseline | 2.1 percent, below the 2.9 percent baseline, rising |
| Hospitalization rate, adjusted for reporting delay | Not stated | 1.2 per 100,000 |
| Pediatric deaths this season | 0 | 0 |
Week 39 figures are as revised in the week 40 report. CDC's wording for week 40: "Seasonal influenza activity is increasing in many parts of the country but remains low." The 2026-27 season began October 4, 2026, so a 5.0 percent positivity in the second week of the season is an early start, and CDC said in week 39 that early-season activity is "higher than typical for this time of year."
Two things matter for a supply buyer. The regions: Region 7 (Iowa, Kansas, Missouri, Nebraska) and Region 8 (Colorado, Montana, the Dakotas, Utah, Wyoming) are now rising alongside the Southeast, South Central and West Coast, and Region 5 with Minnesota and Wisconsin sits next door. The strain: H1N1 at 96 percent points testing volume toward pediatric offices, urgent cares, school nurse offices and employer clinics rather than hospital labs.
What CDC expects for the rest of the season
Do not confuse an early start with an early peak. CDC's 2026-27 Respiratory Disease Season Outlook, published September 23, 2026, expects a moderate flu season and says "there is no evidence to indicate that a severe season is more likely" than history suggests. It also says national flu hospitalizations have typically peaked between December and February, with the timing inside that window hard to predict. Last season was moderate overall and high severity in children aged 0 to 17.
Read those two statements together. A moderate season that starts in early October and peaks in December or later is a long season. Long seasons burn through test inventory in a steady grind, and they expose the clinics that bought one case in September and planned to reorder "when it gets busy." Lead times stretch exactly when everyone else has the same idea.
Rapid flu tests: what you are buying and what it can tell you
Rapid influenza diagnostic tests, the antigen cassettes most clinics run at the point of care, return a result in about 10 to 15 minutes, and many are CLIA-waived. CDC's laboratory guidance sets the floor: FDA-cleared rapid antigen tests must achieve 80 percent sensitivity for influenza A and B compared with RT-PCR. CDC prefers rapid molecular assays for outpatients because of their higher sensitivity, treats antigen tests as an acceptable fallback when molecular is not available, and does not recommend antigen tests for hospitalized patients.
The line that bites in a rising season: "False-negative (and true-positive) influenza test results are more likely to occur when disease prevalence is high." As positivity climbs, clinicians confirm negatives with molecular more often. That is a clinical call for your medical director. The purchasing consequence is that a clinic stocking only antigen cassettes may see demand for molecular cartridges or send-out swabs rise at the same time. Plan both lines. CDC also advises collecting specimens within four days of symptom onset, so clinics that test on arrival use more tests per positive patient, and the par should reflect how your front desk actually works.
The stocking math for an early H1N1 season
Build the par from visits, not from last year's invoice. The worked example below is illustrative. Put your own numbers in the right column.
| Input | Example clinic | Your clinic |
|---|---|---|
| Respiratory visits per week right now | 60 | |
| Share of respiratory visits tested | 50 percent | |
| Tests used per week today | 30 | |
| Expected growth if local positivity doubles | 2x | |
| Tests per week at the next step up | 60 | |
| Weeks of cover you want on hand | 4 | |
| Par (tests on hand) | 240 | |
| Reorder point (two weeks of the higher rate) | 120 |
Three adjustments:
- Combo kits change the count. A Flu A/B plus COVID combo cassette answers two questions with one swab. If your protocol tests for both on every respiratory visit, combo kits replace two separate tests and your case count drops. If you only add COVID testing on exposure history, keep both lines.
- Add RSV where you see children or seniors. Triple combo kits cover Flu A/B, COVID and RSV. Pediatric offices and senior living nursing stations are the settings where that third line earns its place.
- Check dating before you count. Kits bought for the 2025-26 season may have 12 to 24 months of shelf life. Rotate what is still in date to the front and count it. Do not count anything that expires before January.
Release orders in tranches. Order four weeks of cover now, watch the Friday CDC FluView release, and reorder when your weekly usage crosses the reorder point or your region joins the rising list.
What to order alongside the tests
Testing volume pulls the rest of the respiratory kit with it:
- Swabs and collection supplies if your kits do not include them, plus viral transport media for send-outs.
- Nitrile exam gloves for every swab. Count one pair per test plus 20 percent.
- Surgical masks for symptomatic patients at check-in and respirators for staff, from the N95 respirator and mask line.
- Disinfecting wipes and hand sanitizer for exam room turnover between respiratory patients, from infection control.
For the full method on sizing a respiratory season par across every kit type, see rapid diagnostic test kits inventory planning.
How Keystone fills a flu test order
Keystone Supply Group stocks Flu A/B rapid tests and Flu A/B plus COVID combo kits from Flowflex, iHealth and CorDx in its Edina, Minnesota warehouse, one truck day from Iowa, Nebraska, the Dakotas and the eastern half of Region 8. Case pricing is quoted the same day during business hours, there is no minimum order on in-stock test kits, and approved accounts ship on Net 30. Send your current on-hand count, your weekly usage and the number of weeks of cover you want, and Keystone will quote the gap and hold the delivery date. If you want the reorder to run itself, a standing order at your reorder point removes the Friday scramble.
Keystone's supply disruption monitor tracks the weekly CDC data alongside manufacturer allocations, so you see the regional trend and the supply constraint on one page.
Flu positivity went from 3.9 to 5.0 percent in one week. Your region is either on the rising list or next to it. Browse rapid diagnostic tests or request a same-day quote with your counts and Keystone will have combo kits on your dock before the next FluView release.
Sources
- CDC, Weekly US Influenza Surveillance Report, Week 40 ending October 10, 2026: https://www.cdc.gov/fluview/surveillance/2026-week-40.html
- CDC, Weekly US Influenza Surveillance Report, Week 39 ending October 3, 2026: https://www.cdc.gov/fluview/surveillance/2026-week-39.html
- CDC, 2026-2027 Respiratory Disease Season Outlook (September 23, 2026): https://www.cdc.gov/cfa-qualitative-assessments/php/data-research/season-outlook26-27.html
- CDC, Rapid Diagnostic Testing for Influenza: Information for Clinical Laboratory Directors: https://www.cdc.gov/flu/php/laboratories/rapidlab.html
