Childhood vaccines threatened, ultraprocessed foods, Chagas disease, and winter viruses
The CA Dose: December 5, 2025
It’s been a big week in public health. As federal leadership revises vaccine policy, our West Coast expert committee is on deck to protect regional vaccine access. California is suing some of the world’s largest corporations for harming health with ultra-processed foods. Chagas disease is getting overdue attention as a hidden source of heart problems, and flu and RSV are rising. Let’s jump in.
Federal vaccine policy in flux
ACIP, the advisory committee that guides U.S. vaccine policy, is currently meeting to set federal childhood immunization policy. This morning the committee voted to delay the first dose of the Hepatitis B vaccine. Instead of a fist dose with 24 hours of birth— which has been the standard for 30 years— the panel now recommends delaying it until the child is 2 months old for mother who test negative for Hepatitis B.
This decision prompts concerns among healthcare providers and medical societies across the country, and the details of implementation are still unclear. We’ll know more next week. Katelyn at YLE National is working on key take homes of today’s Hep B vaccine vote for later today.
Today’s ACIP agenda also broadens consideration of the entire childhood vaccination schedule—including its history, the number of doses, timing, and vaccine ingredients.
Remember, ACIP was overhauled this spring, when experts were replaced by mostly vaccine skeptics. That move led to the formation of the West Coast Health Alliance (WCHA), as an independent vaccine advisory committee for California, Washington, Oregon, and Hawaii.
When new ACIP recommendations are not science-based and differ from our regional expert committee recommendations, this will be the biggest test of WCHA’s authority and control over vaccine access. It’s too early to tell where this may land: we first need to know exactly what ACIP recommends—which vaccines, for whom, and when. We don’t expect decisions on other childhood vaccines from ACIP this week.
Wednesday, Katelyn at YLE National, Jess Steier at Unbiased Science, and I posted a guide to “pre-bunk” any misleading or false information emerging from this week’s ACIP meetings. You can read it here.
We’ll be following this closely and will provide updates.
California takes on Big Food
On Tuesday, San Francisco filed the nation’s first lawsuit against major food manufacturers over ultra-processed foods (UPFs). Targeting some of the world’s largest food corporations, including PepsiCo, Kraft, and Coca-Cola, the suit argues that the industry, not taxpayers, should carry the cost of treating diet-related chronic diseases related to UPF consumption.
The lawsuit is built on two main claims:
Public health crisis: The suit contends that UPFs, which now constitute over 50% of the American food supply, are causing a “chronic disease epidemic,” including Type 2 diabetes, heart disease, stroke, obesity, cancer, and dementia. The city says these preventable diseases have unfairly burdened local government and taxpayer-funded healthcare systems.
Deceptive marketing: The food corporations are accused of “unfair and deceptive acts,” marketing products as “healthy” or “natural” that they knew were damaging health. The suit claims these products are specifically engineered for maximum addictive quality and low cost, and many are targeted at children.
The lawsuit seeks financial penalties, a ban on more deceptive marketing, and funding to offset health care costs attributable to widespread UPF consumption.
The challenge of defining “ultra processed.” A key industry defense will center on the lack of a uniform definition for ultra-processed foods, arguing that blanket classification is misleading.
Luckily, California was also the first state to develop a definition of ultra-processed foods when it passed a law earlier this year to ban UPFs from school lunches. I described this law in a prior post here.
A history of taking on industry. This lawsuit is the latest version of a legal strategy used by California to shift financial burden from the public to corporations that put profits over health. This has held manufacturers accountable across several major public health crises, including:
Tobacco: Lawsuits secured hundreds of millions of dollars in settlements and forced the industry to pay for the public health toll their products caused.
Lead paint: California’s legal action resulted in a $305 million settlement from manufacturers for abatement programs and removing lead paint in homes.
Opioids: Billions of dollars from manufacturers and distributors are now going to state and local overdose prevention efforts, including substance use recovery.
Toxic chemicals: The state sued manufacturers of PFAS, or “forever chemicals,” to pay for the investigation, cleanup, and treatment of contaminated drinking water supplies.
Youth mental health: California co-led a lawsuit against Meta for designing platforms damaging to youth mental health, to halt deceptive practices and recover damages.
Big oil: The state sued five of the world’s largest oil companies for deception about climate change, seeking damages for the resulting costs to the state.
In each case, the legal focus shifts from blaming individual consumers to holding corporations accountable.
Even with this track record, taking on Big Food is big—we should expect a protracted battle. California can challenge powerful corporate interests, and win, because we have the political will, legal resources, and a public health mindset. Manufacturers are aware that a precedent is being set. Other states—especially those that can’t mount this kind of fight on their own—benefit by following in California’s slipstream.
Chagas disease is getting overdue attention
Recent research shows that Chagas disease is an under-recognized contributor to both heart disease and gastrointestinal illness in California. I asked rising epidemiology star Linette Kingston to help break it down for you.
Chagas disease is caused by Trypanosoma cruzi, a parasite spread by insects called “kissing bugs” because they tend to bite on the face. Infection happens not through the bite itself, but from droppings, which can be scratched into bite wounds or the eyes, nose, or mouth.
When people are infected, the disease progresses through two distinct phases. The acute phase lasts weeks to months, and includes eyelid swelling, fever, rash, fatigue, and body aches.
The chronic phase is more serious, and can affect the muscles of the heart and intestines years after infection. Long term complications can include a weakened heart causing cardiac failure, and an enlarged esophagus and intestines, causing difficulty swallowing and severe constipation.
Why it’s important to diagnose early. Anti-parasite medications effectively treat Chagas disease, but only early in the disease. UCLA and other California medical centers have begun routine Chagas disease testing for patients with unexplained heart disease or certain gastrointestinal conditions.
Native to California. In September, the CDC published a perspective piece calling for Chagas disease to be declared endemic, or native, in the U.S. (as opposed to a disease that’s only acquired abroad, like malaria). While this status may be debated nationally, it’s clearly endemic in California. Chagas disease is part of our state ecology.
California is one of six states that has all three factors needed to sustain local Chagas disease transmission: 1) kissing bugs infected with Trypanosoma cruzi parasites are found throughout the state, particularly in Southern and Central California; 2) wild and domestic animals—including woodrats, raccoons, opossums, and dogs—maintain the parasite in the environment; and 3) locally-acquired human cases.
Tracking the disease. Because testing and reporting haven’t been routine, it’s hard to know the true burden of Chagas disease in California. Some researchers estimate up to 100,000 cases statewide, but this is based on models, not actual case reports.
Chagas is now reportable in Los Angeles and San Diego counties. As reporting, clinical awareness and testing expands, we’ll likely see bigger numbers—not necessarily because the disease is increasing, but because we’re better at counting existing cases.
The vast majority of reported cases in California are among people who come from countries where the disease is more common, especially Central and South America. Locally acquired cases, while rare, prove that Chagas is also a local threat.
How to prevent Chagas disease. Preventing serious disease has two components—preventing kissing bug exposure, and getting treatment during the acute phase to prevent later complications.
We can take the following steps to reduce contact with kissing bugs:
Use screens on windows and doors, and seal gaps in your home’s exterior.
Keep outdoor lights off at night when possible, as they attract kissing bugs.
When camping or spending time outdoors in rural areas, use insect repellent and sleep in tents with sealed seams.
If you’re bitten by a kissing bug, wash the area with soap and water, and avoid scratching. Contact your healthcare provider if you develop fever, rash, or eyelid swelling in the days or weeks following exposure.
Why this matters. Recognizing Chagas disease as native to California—even if the risk of locally acquired disease is low—is a shift in how we approach this disease. We’re moving from viewing it solely as an imported illness to understanding it as a local health concern requiring systematic screening, treatment, and prevention efforts. Early detection through expanded testing can prevent the devastating cardiac and gastrointestinal complications that happen when the disease goes unrecognized for years.
Holidays and stress
The holiday season is here, and while we celebrate joy and connection, it can also bring stress, loneliness, or financial strain. If you’re having trouble getting into the holiday spirit, you’re not alone—a recent American Psychological Association survey found that nine in ten (89%) adults feel stressed during the holiday season.
If you’re struggling or worried about a loved one, reach out. If you’re in crisis, you can call or text 988 or chat online at 988lifeline.org, 24/7, 365 days a year. You’ll find trained, compassionate crisis counselors offering confidential support for suicidal, mental health, and substance use-related crises. For non-crisis help, you can find peer-to-peer emotional support at the California Peer-Run Warmline by calling or texting 1-855-600-WARM (9276). Taking action to seek help is a sign of strength, not weakness.
Infectious disease weather report
Influenza and RSV levels continue to rise slowly in most regions, but neither has surged. There’s often a “warm up” interval like this, where the virus percolates at low but increasing rates at the season’s start, before an enduring spike in transmission.
This graphic of hospital emergency room visits for flu over the past two years shows we’re right at the usual inflection point.
Covid 19 remains at low levels across the state and nation. It’s not too late to get the protection of the vaccine. Schedule an appointment here.
Bottom line
This week’s edition highlights familiar tension between California’s approach to vaccines and that of federal leadership. But our lawsuit against Big Food is different— it’s a “strange bedfellows” moment, as liberal San Francisco and the MAHA movement share a vision to protect our communities from ultra-processed foods. The effort is far more likely to succeed with bipartisan support. Hopefully we can remain open to other shared goals for community health, knowing we’re far more powerful when we’re pulling in the same direction.
Love,
Matt
Dr. Matt Willis is the author of Your Local Epidemiologist in California. A California native, he’s served as a primary care physician, CDC epidemiologist, and public health officer for Marin County, where he guided the pandemic response. He lives in Marin with his wife, children, and their dogs Teddy and Ramona.
Linette Kingston is a Masters in Public Health student studying epidemiology and biostatistics at UC Berkeley. Linette coauthored this week’s section on Chagas disease.
Thank you to Bernardo Moreno Peniche, MD, PhD, MSc, one of the authors of the recent CDC perspective piece on Chagas disease, for his insights and feedback.
My comment is really a question, Dr Willis. When you have time please. I am searching for a decent source of Covid and RSV immunizations for a relative who does not currently have insurance. A local pharmacy here in CA has quoted a price tag of $610. for the two. Can anyone imagine who has that to spend if they are without insurance? Are there any resources for him anywhere? Thank you.
When I read that hepatitis b vaccine is no longer recommended, it made me wonder if a parent could request it for their newborn? Is that even a possibility? I have watched the benefits of the vaccine over these 30 years. I was a newborn RN when this vaccine was introduced and felt some pride about these longterm beneficial results.