Measles deaths at two nationally and four in Pennsylvania, and flu positivity at 3.4%: this week's vaccine plan
CDC's national measles page now lists two deaths for 2026 while Pennsylvania counts four, and flu test positivity rose a fourth straight week to 3.4%; this week's brief explains what the numbers change for a household's next appointment.
Flu season has started to show up in the numbers. During the week ending September 26, clinical laboratories across the country tested 33,547 respiratory specimens and found influenza in 1,151 of them, a positivity rate of 3.4%. The rate has now climbed four weeks in a row: 1.3%, then 1.8%, then 2.7%, now 3.4%. 1
Measles moved in the harder direction. CDC's national page, updated October 2, now lists two confirmed measles deaths for 2026, up from one the week before. Pennsylvania's health department, which does not wait for a national definition, has confirmed four measles-associated deaths in the state's outbreak. 23
The household to-do list is the same as it was in September: a flu shot for everyone 6 months and older, and two documented MMR doses for everyone who can receive them. What changed this week is the calendar on the first job and the evidence on the second.
Flu tests are turning positive faster
CDC published its Week 38 report on October 2, covering the week ending September 26. Clinical laboratories tested 33,547 specimens and found 1,151 positive, a 3.4% rate and the highest of this young season. Public health laboratories confirmed 79 positives, all of them influenza A; of the 55 they subtyped, 53 were A(H1N1)pdm09 and 2 were A(H3N2). Early circulation is running heavily toward one of the two influenza A components this season's vaccine covers. No specimen carried H5 avian influenza, and no new human infection with a novel influenza virus was reported. 1
Outpatient clinics logged fever with a cough or sore throat in 1.7% of visits, up from 1.6%; among children 0 through 4 the share was 5.5%. Emergency departments recorded a flu discharge diagnosis in 0.4% of visits, up from 0.3%. Fifty-five jurisdictions reported minimal respiratory activity and none reported low, moderate, high, or very high. Among the core-based statistical areas that reported, 7 showed moderate activity and 26 showed low. 1
Hospitals reported 2,572 laboratory-confirmed flu admissions during the week, or 0.8 per 100,000 people, with the highest rate among adults 65 and older at 2.6, then adults 50 to 64 at 0.8 and children 0 to 4 at 0.6. Laboratory-confirmed flu hospitalizations since October 1, 2025 reached 31,513. Influenza accounted for 0.1% of deaths in the week ending September 26, and no new pediatric deaths were reported; the 2025–26 season total stands at 195. 1
A 3.4% positivity rate in early October is what the start of a flu season looks like, not the middle of one. For a family, it sets the timing rather than the alarm: protection takes about two weeks to build after a shot, and CDC's guidance is to be vaccinated by the end of October. 4
Measles deaths now stand at two nationally, four in Pennsylvania
CDC updated its measles page on October 2 with figures reported through October 1. The United States has recorded 3,887 confirmed cases in 2026, 3,869 of them reported by 47 jurisdictions and 18 among international visitors. The year has produced 42 outbreaks, and 95% of cases, or 3,700, are outbreak-associated. Hospitalizations reached 352, equal to 9% of confirmed cases, including 14% of cases in children under 5 and 12% of cases in adults 20 and older. The page now lists two deaths for 2026, marked as subject to change; it listed one the week before. 2
Cases remain concentrated in a few states: Pennsylvania has reported 963, South Carolina 670, Utah 535, Wisconsin 207, Texas 192, and Virginia 178. By week of rash onset, the national count has come down from its August peak of 229 cases in the week starting August 23, then 169, 185, 150, and 143, with 60 in the still-incomplete week starting September 27. 2
The two death counts measure different things. CDC's national number, two, is a work in progress: the agency is still building a standard measles-death case definition with the Council of State and Territorial Epidemiologists, so it reports deaths cautiously and marks them subject to change. Pennsylvania published its own definition, a death within 30 days of symptom onset in a person with clinical evidence of measles and a positive laboratory test that is not due to an unrelated cause, and has confirmed four deaths under it. Both counts can be right at once, because each answers a different question. 23
IZ Express, the professional bulletin Immunize.org publishes each week, reported in its September 30 issue that the Johns Hopkins U.S. Measles Tracker counts 3,782 confirmed cases nationally and that Pennsylvania recorded 129 new confirmed cases during the week. The tracker and CDC draw on the same reports but update on different schedules, which is why their totals sit close together and rarely match exactly. 5
The population-level picture is unchanged and still short of where it needs to be. Two doses of MMR are 97% effective at preventing measles and one dose is 93%. Kindergarten MMR coverage was 92.4% for the 2025–26 school year, down from 95.2% before the pandemic, leaving roughly 280,000 kindergartners without the community protection that a 95% threshold provides. 2
What a school-entry mandate rollback could do, in one model
A study published September 28 in PNAS looks at what happens to measles transmission when school-entry vaccination requirements come off. The authors built an age-structured model of how measles spreads between children and adults, calibrated it on the 2025 outbreak in Gaines County, Texas, and applied it to Florida using that state's demographics and MMR coverage. They estimate that Florida's current coverage already sits below the level needed to stop sustained transmission, and that simulated declines in coverage after a mandate change would produce outbreak sizes not seen since before the vaccine existed, including projected pediatric deaths within five years. 6
The result is a projection, not an observation. It describes what could happen under stated assumptions, and it rests on one Texas outbreak and one state's demographics. What it does show is the shape of the risk: where coverage already sits below the herd-immunity threshold, small drops in child vaccination produce large increases in outbreak size. 6
The studies, the pipeline, and two more shots of the season
The three immunology journals this channel follows, Cell, Immunity, and Nature Immunology, published this week into cancer biology, mitochondria, and basic immune regulation, with nothing that touches a household vaccine decision. The clinically relevant study of the week came from Vaccine. Researchers in Taiwan tracked adults 65 and older through the severe 2024–25 season, when severe cases there rose from 1,433 to 2,215 and deaths from 297 to 545, and measured how well the standard-dose inactivated trivalent vaccine protected them: 71.9% effectiveness against death within 30 days, 70.0% against ICU admission, 58.2% against hospitalization, and 44.8% against outpatient visits. The vaccine held up even as coverage in that age group fell from 53.6% to 48.1%. These numbers come from one country's health system in one season, so read them as a real-world guide to what a flu shot does for older adults, not as a U.S. estimate. 7
CDC has no U.S. vaccine-effectiveness estimate for the 2026–27 season yet. Its vaccination-trends page, reported October 2, carries 2025–26 data through May 23 and states that updates for that season ended in May, and its effectiveness index lists seasons only through 2025–26. The newest U.S. figure is last season's 36% overall, with a confidence interval of 33% to 39%. A season's first estimate arrives in the winter or spring after its networks finish enrolling, so a 2026–27 number cannot exist this early. 8910
Two other shots joined the fall conversation. CDC posted updated interim clinical considerations for COVID-19 vaccines on September 23, and this week's IZ Express bulletin carried them. The guidance recommends a 2026–27 COVID-19 vaccine for all adults 18 and older, two doses six months apart for adults 65 and older, and vaccination for children 6 months through 17 years with moderate or severe immunocompromise, with shared clinical decision-making for other children. The page flags where CDC's advice runs beyond the FDA label. 511
October 1 also opened the RSV preventive-antibody window for infants across most of the contiguous United States. That is the point at which clinics should recall infants under 8 months born in late spring or summer who were not protected through maternal vaccination or a birth dose of nirsevimab (Beyfortus) or clesrovimab (Enflonsia). Antibody products can be given alongside routine vaccines. 5
The FDA's vaccine advisory committee met October 1 to recommend the strains for the 2027 Southern Hemisphere flu vaccine, a separate product made for the opposite hemisphere's season. That meeting leaves the 2026–27 U.S. vaccine in pharmacies now untouched. 12
On the product side, nothing moved. Moderna's mFLUSIVA remains approved for adults 50 and older, with the 65-and-older indication granted under accelerated approval based on immune responses and expected availability during the 2026–27 respiratory season, and the company still offers no local stocking, price, or coverage detail. Pfizer's newsroom showed no respiratory-vaccine release this week; its newest entries concern vitiligo, atopic dermatitis, and cancer. CDC's routine immunization schedule pages still carry the July 2, 2025 addendum. 131415
What to do this week
- Book flu shots for everyone 6 months and older. Aim to finish by the end of October, because protection takes about two weeks to develop. 4
- Start a first-time flu shot for a young child now. Children 6 months through 8 years who need two doses should get the first as soon as vaccine is available, since the second comes at least four weeks later. 4
- Ask for a preferred flu formulation if someone in the house is 65 or older. Fluzone High-Dose, Flublok Recombinant, and Fluad Adjuvanted are the three CDC recommends preferentially; any age-appropriate flu vaccine works if none is in stock. 4
- Find the MMR records for school-age children. Two documented doses need no further action; a single dose or no record is the gap to close with a pediatrician, a state immunization registry, or a county health department. Complete MMR at least two weeks before an international trip. 23
- Ask about RSV antibody for an infant born this spring or summer. The October 1 window is when most clinics resume dosing for babies who were not protected at birth. 5
- Ask about the 2026–27 COVID-19 vaccine if anyone in the household is 18 or older or has a higher-risk condition. The updated guidance covers adults, older adults, and children with immunocompromise. 11
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
- 5IZ Express Issue 1896
immunize.org
- 6
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- 12
- 13IR Insights: Introducing mFLUSIVA
modernatx.com
- 14Newsroom | Pfizer
pfizer.com
- 15
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