The CA Dose, August 21, 2025
Covid surge, an emerging disease, protecting science, and more
Welcome to the second edition of CA YLE! Thank you for joining this growing community from all corners of the state. Please keep your emails and comments coming—this newsletter is for you, and I want it to be useful.
Today I’m covering the ongoing Covid-19 summer surge, an emerging disease that you may not have heard of yet, a San Francisco judge who’s protecting science, and more. Let’s dive in!
Covid-19 surge
California’s in the middle of a Covid-19 wave, and statewide rates are among the highest in the nation. Emergency Department (ED) visits for Covid are more than twice the level they were last winter, but remain below last summer’s wave. Wastewater data show “High” Covid activity in all regions of the state.
ED visits for children under age 12 are rising quickly, and are more than twice the statewide average. Among those age 75 or older—our residents at highest risk for bad outcomes—ED visits for Covid have nearly doubled in the past month.
COVID vaccine update
We’re in an unfortunate limbo, created by an administration that’s uncommitted to vaccines, between the slow shutting down of ’24-’25 vaccine availability and access to the ’25-’26 version. This is particularly concerning in California as our transmission rates continue to climb.
My take: if you’re in a higher risk group, get a shot now, if you can. If you were my patient, were at high risk, and hadn’t had a Covid shot this year, I’d probably recommend getting the current vaccine if you can find it locally.
If you can’t get a vaccine right now, sign up to get the new vaccine when it becomes available. We’ll know more after tomorrow’s FDA announcement.
Remember that an N-95 mask is highly protective when you’re indoors. Now’s a good time to mask in indoor public places if you’re in a high risk group.
Keep an eye on our social media accounts. We’re trying to answer a few extra questions as they come up on Instagram and elsewhere.
Other respiratory viruses
While Covid surges, RSV and influenza are still at flat summer-time levels. In California, RSV season tends to start in September, and flu typically starts rising in November. Both are well tracked by the CDPH respiratory weekly report. I’ll keep you informed.
Remember, despite the delays around Covid vaccines, we have a full green light for flu and RSV fall vaccines, and they’re available in clinics and pharmacies across the state.
New World what? Getting to know an emerging threat
If you haven’t heard of New World Screwworm (NWS), and you don’t like the sound of it, you’re not alone. I expect we will hear more about it in the news over the next few weeks, because this pest is migrating our way—the USDA says it’s about 350 miles south of the U.S. border. This is an attempt to prepare you for those headlines.
“Landfall” for NWS in the U.S. is expected to hit Texas first. I’ll be watching closely, since this may predict our experience in California if migration continues.
What is NWS and how does it cause illness?
NWS is a parasite that was eradicated from the U.S. and most of Central America decades ago, but is resurging. It mainly affects animals and can have a devastating impact on livestock and wildlife. Human cases are rare.
Screwworms come from the eggs of the NWS fly, so they’re technically maggots. The NWS fly, about the size of a housefly, lays its eggs around a skin wound or, less often, on other sensitive skin, like around the eyes and nose. When the eggs hatch, larvae (“screwworms”) burrow down into flesh. This creates wounds that can be life threatening.
Once NWS flies get established in an area, this cycle repeats indefinitely until the pest is locally eradicated.
Human cases are rare, and treatable if detected early. In Central America, where NWS is now endemic, 444 cases have been reported since the beginning of 2024. People working closely with livestock are at highest risk. We’ve seen three U.S. cases since 2014, and all were infected abroad. Treatment usually involves surgery.
It could have a big impact on California farmers and consumers. A 1976 outbreak in Texas—our last major outbreak in the U.S.—affected an estimated 1,488,256 cattle and 332,600 sheep and goats. The USDA estimates an outbreak of that size today would cost Texas $1.8 billion. California has fewer cows than Texas—about 1.5 million head of cattle—but hundreds of millions of dollars are at stake if NWS is not controlled. For consumers, meat and milk prices increase when dairy and farms and ranches are impacted.
What’s the federal government doing?
Last Friday, USDA Secretary Rollins outlined a sweeping national response plan.
One key strategy is the release of millions of sterilized male NWS flies to the air over impacted areas. When females mate with a sterile male, they end up with unfertilized eggs. This approach has helped clear NWS flies from our borders before.
To prepare for a resurgence, federal agencies are providing veterinarians and doctors education to recognize and treat NWS. And people who work most closely with animals are being trained to take special precautions.
How worried should we be?
Right now, it’s wait and see. As you hear more, remember there are proven measures to control NWS, and human cases are rare. You can look to YLE and your health department for when it’s time to take action.
Protecting science in California
Last week U.S. District Judge Rita Lin (SF) ordered the National Science Foundation to restore about 300 grants to UCLA that were suspended on July 29. She noted that NSF “failed to provide the requisite grant-specific reason for halting funding” or to “adequately consider the impact on the researchers.” She gave NSF a firm deadline to reinstate the grants.
It can be confusing to follow the rapid-fire federal threats and state responses. Here’s a brief timeline.
July 29: Justice Department ruled that UCLA committed civil rights violations during campus protests, and suspended federal grants including 300 National Science Foundation grants
August 8: President Trump demanded UCLA pay $1 billion fine to settle
August 12: Federal judge Lin ordered NSF to restore grants to UCLA, citing Administrative Procedure Act (APA) violations and inadequate reasoning for suspending the grants
August 18: UCLA Board of Regents met in closed session to discuss $1 billion settlement
By comparison: Columbia and Brown settled for $221 million and $50 million, respectively.
August 19: The NSF grants should have been reinstated. $1 billion settlement is still on the table.
Why does this matter to us?
“Suspended grants” may feel abstract. In fact, many UC grants are critical for the health of communities. I’ve seen it firsthand as a health officer for Marin County.
During the pandemic UC Santa Cruz helped our team track outbreaks in schools, UCSF labs identified new variants, and UC Berkeley helped us analyze sewage for viruses when that was a new idea. It worked really well, and now wastewater is a cornerstone of virus surveillance.
Local public health didn’t fund this work, and we couldn’t have. UC grants enabled us to innovate together, to solve local problems while advancing science nationally.
Judge Lin’s decision is an example of defenders in high places ensuring that federal agencies follow the law, and that our researchers have recourse when rules are sidestepped. It’s critical that our universities, lawyers, and courts are willing to challenge federal action that jeopardizes science.
A possible California solution
California is considering legislation that could make our researchers less dependent on the prejudice of federal leadership. A bill (SB 829) making its way through committees in Sacramento would create the California Institute for Scientific Research Fund, to award grants to “public or private research companies, universities, institutes, and organizations for scientific research and development.”
Dear Public Health
Last week the YLE team compiled over 300 messages of gratitude and encouragement to public health workers following the attack on the CDC. Thank you to California readers who contributed, including the Steeles, who summed up what so many of us feel:
“I hope you can take a moment to rest, to breathe, and to remember that there are people who see you, value you, and stand beside you. You are not alone.”
-Teresa and Bruce Steele, Rancho Palos Verdes, California.
The California Department of Public Health (CDPH) maintains a list of local health departments statewide with contact information. Consider sending this PDF to your local public health team with a note. I know they could use it.
Question grab bag
We’re getting a lot of emails from you! Keep them coming. We love to hear what’s on your mind. Here are two of your questions answered:
Q: All of a sudden we’re hearing about alpha-gal—a tick bite that can cause allergies to red meat? Do we have that in California?
Alpha gal was covered by YLE National on Monday. AGS is getting new national attention probably because of a big cluster of cases reported in Martha’s Vineyard. The Lone Star tick that’s most known for carrying it isn’t found in our state. A few cases have been reported in Western Blacklegged ticks, which we have. AGS is rare in California.
Location of alpha-gal cases, per one million population, 2017-2022
Q: What else can we do to support public health workers?
Yesterday, current and former CDC, NIH, and HHS staff released an open letter in response to the Aug. 8th attack, demanding “work environments free from violence… and public health leaders who tell the American people the truth.” It’s open for the public to sign—another small but meaningful action you can take.
Bottom line
That’s it for this week. There’s always something interesting and important happening that affects our health in this beautiful state. I’m excited to help translate some of it for you. See you next week!
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 a dog named Teddy.
Dr. Willis, we just sent a link of the PDF to the Los Angeles County Dept. of Health
Doctor Willis, our Elementary School says students who test positive for COVID but have no fever are allowed to go to school unmasked because they are not contagious. Is that true?