Flu positivity jumps to 5.0%, measles reaches 4,410, and Pennsylvania investigates a sixth death: this week's vaccine plan
Flu test positivity rose to 5.0% in the week ending October 10 and confirmed measles cases reached 4,410, while a new federal study measured how well the whooping-cough series protects young children; this week's brief sets out what a household should book now and what is worth waiting for.
Flu has moved faster in the past week than at any point this fall. Clinical laboratories tested 45,331 respiratory specimens in the week ending October 10 and found influenza in 2,270 of them, a positivity rate of 5.0%. 1
That is the sixth consecutive weekly increase, and the largest single-week jump of the season so far.
Confirmed measles cases reached 4,410 as of October 15, with 451 people hospitalized. 2 Pennsylvania, at the center of the year's outbreak, reported 1,260 cases on October 16 and said it is reviewing one more death. 3
The household list keeps its shape: a flu shot for everyone 6 months and older, two documented MMR doses, and every routine childhood dose brought current. Three things moved this week — the flu curve, Pennsylvania's outbreak, and the evidence on how well the whooping-cough series protects small children.
Flu positivity jumped to 5.0% in one week
The weekly rise reads 1.3%, 1.8%, 2.7%, 3.4%, 3.9% and now 5.0%. 1 CDC published 3.6% for the previous week on October 9 and carried 3.9% in this report, a reminder that the newest number revises as late reports arrive. 14
Outpatient clinics logged fever with cough or sore throat in 2.1% of visits, up from 1.8% and still below the national baseline of 2.9%. Emergency departments recorded a flu discharge diagnosis in 0.8% of visits. 1
Hospitals reported 4,024 laboratory-confirmed flu admissions, a rate of 1.2 per 100,000 people. Influenza accounted for 0.2% of deaths in the week, up from 0.1%. 1
One jurisdiction sits at moderate activity and none at high. The highest activity is on the West Coast, in HHS regions 9 and 10. No pediatric death from the 2026–27 season has been reported yet, and CDC recorded no new human infection with a novel influenza virus as of October 14. 1
Public health laboratories subtyped 251 influenza A specimens: 242 were A(H1N1)pdm09 and 9 were A(H3N2). Since the week ending May 30, 79.3% of typed influenza A viruses have been A(H1N1)pdm09. 1 This season's vaccine carries an A/Missouri/11/2025 (H1N1)pdm09-like component, one of three that were updated for 2026–27. 5
Mid-October is still the front of this season. CDC counts 2026–27 from October 4, and influenza-like illness remains under its baseline. 4 Protection takes about two weeks to build after a shot, and CDC's target is to finish by the end of October. 6
Measles at 4,410, and Pennsylvania reviews a sixth death
CDC updated its measles page on October 16 with figures reported through October 15. The national count is 4,410 confirmed cases in 2026, up 330 in a week, and 451 people have been hospitalized, 10% of all cases. 2
Age decides much of that risk. Fifteen percent of cases in children under 5 were hospitalized, along with 14% of cases in adults 20 and older and 5% in school-age children. 2
Forty-two outbreaks have been reported, and 96% of this year's cases are outbreak-associated. Of those 4,228 cases, 2,844 came from outbreaks that began in 2026 and 1,384 from outbreaks that began in 2025. 2
By week of rash onset, the national curve has flattened rather than fallen: 190 cases in the week starting September 27, 130 the following week, and 50 in the still-incomplete week starting October 11. CDC revises recent weeks upward as reports arrive. 2
Pennsylvania's October 16 release reports 1,260 confirmed cases in 43 counties, 38 of them new since October 14, and 238 hospitalizations. The state counts five confirmed measles-associated deaths and says it is investigating a recently reported death in Franklin County. 3
CDC's national page lists Pennsylvania at 1,237, a little behind the state's own figure, because the two pages draw on the same reports on different days. The death counts differ for another reason. CDC is still building a standard measles-death classification and reports cautiously, while Pennsylvania applies its own published criteria; a state or county finding can arrive before it reaches the national count. 23
The vaccination response is the number moving fastest. Pennsylvania providers gave more than 56,000 MMR doses in September against a typical month of about 25,000, and more than 23,000 in the first two weeks of October. State nurses have given 9,300 doses at 210 pop-up clinics. 3 Two doses of MMR prevent measles in 97% of people who receive them. 3
A whooping-cough study and a Montana child's death
Flu and measles have held the attention this fall, and two items published in the past week point at the doses that get postponed while that happens.
CDC's weekly report for October 15 carries a vaccine-effectiveness study from Alaska's 2024 pertussis outbreak, which reached the highest incidence the state has recorded. Investigators compared 84 children aged 6 months to 6 years with laboratory-confirmed whooping cough against 229 children of the same age. The comparison group was tested for pertussis and did not have it. 7
Three or more DTaP doses were 96.2% effective against laboratory-confirmed pertussis. One or two doses were 85.3% effective. Children with no doses had about 26 times the odds of the disease, with a confidence interval running from 10 to 71 times. 7
The authors note that children who had finished the three-dose primary series but had not yet received boosters scheduled at 15 to 18 months and 4 to 6 years may have been more susceptible as protection waned. They describe the pattern as consistent with earlier research and say their sample was too small to test it. 7
On October 5, Montana's health department reported that a child died in September from complications of invasive Haemophilus influenzae type b, or Hib. The child had not received the Hib vaccine. 8
Hib is the vaccine-preventable form of a common bacterium, and no vaccine covers the other strains. Routine doses come at 2, 4 and 6 months, depending on brand, and at 12 to 15 months; children under 5 who are unvaccinated or partly vaccinated should catch up. 8
Montana's state medical officer, Douglas Harrington, used the announcement to ask parents to keep children current on all recommended vaccines, Hib included. The state has recorded four pediatric deaths from invasive H. influenzae since 2012, and none of the earlier ones was type b. 8
Where the guidance and the products stand
There is no U.S. flu vaccine-effectiveness estimate for this season yet, because an estimate needs a season's worth of cases behind it. CDC's vaccination-trends page, updated October 16, says 2026–27 figures will post later this fall; its effectiveness index ends at 2025–26. 910 Last season's estimate was 36% against outpatient flu visits, with a range of 33% to 39%. 11
If you are 50 or older and wondering whether to wait for Moderna's mRNA flu vaccine: mFLUSIVA is approved for adults 50 and older, with the 65-and-older indication granted under accelerated approval based on immune responses while confirmatory work continues. 12 Moderna expects it to be available in the United States this respiratory season and has published no stocking, price or coverage detail.
Timing is what a household has to decide on. The company has given no date on which a pharmacy near you would have the product.
Pfizer's newsroom showed no respiratory-vaccine release this week; its newest entry was an October 14 announcement of infectious-disease data at a medical meeting. 13 CDC's routine immunization schedule pages still carry the July 2, 2025 addendum. 14
ACIP, the federal committee that votes on vaccine recommendations, has its October 21–23 meeting listed as cancelled because of ongoing litigation. 15 Clinics will keep working from the guidance already in place.
COVID-19 guidance is unchanged since September 23: a 2026–27 vaccine for all adults 18 and older, two doses six months apart for adults 65 and older, vaccination for children 6 months to 17 years with moderate or severe immunocompromise, and shared decision-making for other children. 16 For parents of small children, one detail matters: the Pfizer-BioNTech vaccine is no longer authorized for ages 6 months through 4 years, and Moderna's is the approved product for that group. 16
This week Immunize.org posted age-based 2026–27 COVID-19 standing orders for clinics, built on the recommendations of the pediatric, family-medicine and obstetric societies alongside CDC's interim considerations. 17
The three immunology journals this channel watches produced nothing this week that bears on a household decision. Cell's October 14 issue ran plant sugar sensing and bat flight neuroscience; 18 Immunity's October 12 issue ran allergic skin relapse and immune aging; 19 Nature Immunology's October 14 issue ran autoantibodies in preterm birth and cancer immunotherapy. 20
What to do this week
- Book flu shots for everyone 6 months and older, now. Positivity has risen six weeks straight to 5.0%, protection takes about two weeks to build, and CDC's target is the end of October. 16
- If someone is 65 or older, ask for a preferred product. Fluzone High-Dose, Flublok Recombinant and Fluad Adjuvanted are CDC's preferred choices; any age-appropriate flu vaccine beats none if those are out of stock. 6
- Start a two-dose flu series for a young child. Children 6 months through 8 years who need two doses should get the first now; the second comes at least four weeks later. 6
- Put MMR records in hand. Two documented doses need nothing more; one dose or no record is the gap to close with a pediatrician, a state registry or a county health department. Finish a missing dose at least two weeks before international travel. 23
- Check DTaP and Hib for children under 5. That includes the DTaP booster at 4 to 6 years; the Alaska study measured 96.2% protection after three doses, and Montana's death was in an unvaccinated child. 78
- Ask about the 2026–27 COVID-19 vaccine if anyone is 18 or older. For a child under 5, confirm which product the clinic stocks, since only Moderna's is authorized for that age. 1617
- If you are holding off for this season's effectiveness number or a newer product, weigh what the wait costs. CDC says the season's figures post later this fall, and mFLUSIVA has no published shelf date; both land after the October window closes. 912
This brief provides general health journalism for U.S. families. A physician, pharmacist, or local public health department can evaluate individual medical histories and confirm clinic-specific product availability.
References
- 1
- 2Measles Cases and Outbreaks
cdc.gov
- 3
- 4
- 52026-2027 Flu Season
cdc.gov
- 6
- 7
- 8
- 9
- 10
- 11
- 12IR Insights: Introducing mFLUSIVA
modernatx.com
- 13Newsroom | Pfizer
pfizer.com
- 14
- 15ACIP Meeting Information
cdc.gov
- 16
- 17IZ Express Issue 1898
immunize.org
- 18
- 19
- 20
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