Last year’s flu season was the worst California had seen in years — and state health officials warn this year could potentially be just as bad.

While forecasting disease isn’t an exact science, there are some troubling signs. In Asia, the flu has made an early comeback, and quickly swelled to epidemic proportions in Japan and Taiwan.

And stateside, some experts are sounding the alarm about continued lower uptake of the flu vaccine. There’s also the possibility of a seasonal COVID-19 wave — the likes of which didn’t materialize last winter, but had been commonplace since the pandemic — as well as a simultaneous rise in respiratory syncytial virus, or RSV.

California health officials have previously forecast that this fall-and-winter’s respiratory virus season is expected to be similar to last year’s. If that’s the case, flu would again be the dominant virus fueling hospital admissions compared to COVID-19 and RSV. During the winters of 2022-23 and 2023-24, COVID made up the majority of California hospital admissions caused by respiratory viruses.

“Having people get vaccinated is going to be really key for influenza,” said Dr. Peter Chin-Hong, a UC San Francisco infectious diseases expert.

While flu, COVID and RSV are currently at low levels in California, there are signs that respiratory virus season is starting to gear up as temperatures drop and people spend more time indoors.

Compared to rates recorded in the summer, the Los Angeles County Department of Public Health has seen increases in people reporting cough, fever, chills, aches, sore throat and runny nose, officials said, citing a text-based health survey. The test positivity rate for rhinoviruses and enteroviruses, which typically cause the common cold, is 19.87%. That’s higher than that of the virus that causes COVID-19, 4.2%; or the flu, 1.04%.

In San Francisco, doctors have seen the number of colds being reported in the hospital double, Chin-Hong said. Some workplaces in the Bay Area have seen a number of employees call out sick.

With RSV, flu and COVID-19 rates expected to climb by the holidays, “this is a perfect time to get immunized,” the L.A. County Department of Public Health said in an email.

The fall and winter of 2024-25 brought the nation’s worst flu season in many years, according to the U.S. Centers for Disease Control and Prevention.

The number of children who died from flu last season was the highest since the H1N1 swine flu pandemic season of 2009-10, according to a recent report published in the CDC’s Morbidity and Mortality Weekly Report. Officials reported 280 confirmed deaths among children last season, and about 9 in 10 of those kids were not vaccinated.

Health officials became particularly concerned about reports of a rare, severe complication that targets the brain — influenza-associated encephalopathy, or IAE, which was reported in 109 children nationally last season.

Three in four children with IAE needed intensive care treatment. The median age of children with IAE was 5, and 55% of those diagnosed with the condition had no underlying health conditions.

Of those children, 37 had acute necrotizing encephalopathy, or ANE, a particularly severe form of the disease that results in rapid neurologic decline. Two in five children with ANE died.

Only 1 in 6 of the kids with IAE who were eligible to be vaccinated had gotten the flu shot, health officials say.

The CDC recommends that everyone age 6 months and up get a flu vaccine. New this year, officials are allowing people to order FluMist to be mailed to them at home. FluMist is approved for people ages 2 through 49 and administered by nasal spray rather than injection.

Doctors have been concerned about declining flu vaccination levels. As of late April, just 49.2% of children had gotten a flu shot, lower than the 53.4% who had done so at the same point the previous season, according to preliminary national survey results. Both figures are much lower than the final flu vaccination rate for vaccine-eligible children during the 2019-20 season, which was 63.7%.

Among adults, 46.7% had gotten their flu shot, slightly down from the 47.4% at the same point last season, according to the preliminary survey results.

“Before the COVID-19 pandemic, flu vaccination coverage had been slowly increasing; downturns in coverage occurred during and after the pandemic. Flu vaccination levels have not rebounded to pre-pandemic levels,” the CDC said.

Early data from the Southern Hemisphere indicate that the flu shot’s effectiveness was decent this season — cutting the risk of hospitalization by 50%.

Asia is already reporting plenty of flu cases.

“For influenza right now, it’s raging in Asia,” Chin-Hong said.

Flu is considered to be at epidemic levels in Japan — where news reports say this was the second-earliest start to the season in 20 years — and in Taiwan. Hong Kong health officials have described the flu situation in September and October, before shots became widely available, as “relatively severe.”

The situation there could provide a glimpse of how the flu season will play out in California and beyond.

In the San Francisco Bay Area, officials are also closely monitoring “high” levels in wastewater of a specific kind of cold virus — enterovirus D68, or EV-D68. In rare cases, that virus can cause polio-like paralysis in children called acute flaccid myelitis, or AFM. High levels were reported in a large swath of the Silicon Valley and San Francisco, according to WastewaterSCAN. High levels have also been found in sewage in western San Bernardino County, including Ontario, Chino and Fontana.

The L.A. County Department of Public Health has not yet detected increased signals of EV-D68, and no cases of AFM have been reported this year in Los Angeles or Orange counties.

That virus can transmit through an infected person’s saliva and mucus and likely spreads “when an infected person coughs, sneezes or touches a surface that is then touched by others,” the CDC said.

Parents should call a doctor if their child suffers any symptoms of AFM, which include slurred speech, difficulty swallowing, difficulty moving the eyes, drooping eyelids, pain in the neck, back, arms or legs, weakness in the arm or legs or facial droop.

To protect yourself against respiratory viruses, experts recommend getting vaccinated, washing your hands often, keeping rooms well-ventilated, wearing face masks in crowded indoor public settings, and staying away from sick people.

The California Department of Public Health recommends updated COVID-19 vaccines for everyone age 6 months to 23 months, seniors age 65 and up; as well as older children, teenagers and adults who either have risk factors for severe COVID, or are in close contact with at-risk people.

Children who have never been inoculated against COVID-19 should also get the vaccine, as should pregnant women and anyone else who wants to get the shot, the state says.

RSV immunizations are recommended for everyone age 75 and up, babies younger than 8 months, and pregnant women between 32 weeks to 36 weeks of gestation.

The immunizations are also recommended for adults age 50 to 74 with risk factors, as well as babies with risk factors between 8 months and 19 months. Older adults who have been previously immunized against RSV generally don’t need to get another vaccine, according to current guidelines.

An estimated 40,000 children avoided peanut allergy diagnoses after the guidelines for when to first expose kids to the food allergen changed, according to new research.

The dramatic drop in childhood peanut allergies arrives a decade after a watershed study found that feeding peanut products to babies reduced their chances of developing an allergy by over 80%.

For decades, parents were advised to avoid feeding common allergens, such as peanuts, to infants. In 2015, guidance shifted around peanuts for high-risk kids and expanded two years later.

A study published Monday in the journal Pediatrics found that peanut allergy rates in children under the age of 3 dropped by roughly 43% after the recommendations were expanded in 2017. Rates for all food allergies dropped by about 36%.

“What I was surprised by was the magnitude of the results,” said Dr. David Hill, an attending allergist at the Children’s Hospital of Philadelphia and senior author of the study. Even being able to say that allergy rates plateaued “would be huge news, but the fact that we actually saw a reduction in the onset of new food allergy in kids under 3 is incredible.”

Hill and his colleagues analyzed electronic health records from nearly 50 pediatric practices to track diagnoses of food allergies in about 120,000 children between 0 and 3. Fifteen months marks the peak onset of peanut allergy, according to the study.

Kids were deemed newly allergic if they received a diagnosis code by a provider for a food allergy and were prescribed an EpiPen, Hill said.

The reductions in diagnoses were found even though only about 29% of pediatricians and 65% of allergists reported following the expanded guidance issued in 2017, surveys found.

Confusion and uncertainty about the best way to introduce peanuts early in life led to the lag, according to a commentary that accompanied the study. Early on, medical experts and parents alike questioned whether the practice could be adopted outside of tightly controlled clinical settings.

Sung Poblete, chief executive of the nonprofit Food Allergy Research and Education, who was not involved in the study, hailed it for its focus on real-world data.

While it’s clear that the practice of “eat early, eat often” for foods that can provoke allergic reactions works in a clinical setting, “it’s really important to know that in the real world, this can also decrease incidence and prevalence for the infant population,” she said.

When a person has a peanut allergy, their body responds to the proteins in peanuts as though they’re dangerous. The immune system tries to fight them off, triggering symptoms ranging from hives and diarrhea to anaphylaxis, a life-threatening condition.

Poblete said that the findings highlight the need to change policy to further drive down life-threatening allergy diagnoses. That could include the U.S. Department of Agriculture including peanut products in their infant food packages, she said.

Food allergy prevalence has been on the rise, with 2.2% of U.S. children having a peanut allergy, according to commentary on the new study. Besides delayed introduction of allergenic foods, other risk factors include cesarean section births and antibiotic exposure, according to Hill.

“This is just a call to double down our efforts to understand why it is that children develop food allergies and how we can better treat and ultimately cure these diseases,” Hill said.

Since the period the researchers studied, children’s food guidelines have expanded further. In 2021, the Academy of Pediatrics recommended introducing major food allergens, including peanuts and egg, to all infants between four to six months of age.

The Associated Press contributed to this report.

Designing the system that would bring a slice of Mars back to Earth at NASA’s Jet Propulsion Laboratory — the Southern California lab that pioneered American rocketry and the scientific exploration of our solar system — was her dream job.

As she worked toward degrees in mechanical engineering, she watched JPL launches and became enamored with the photos the lab took on Mars. She attended a JPL open house, which she said felt like “Disneyland.” She applied to work at JPL more than 60 times. When she finally got the job working on the Mars Sample Return Mission, she hoped to spend the rest of her career there.

But on Tuesday, she was one of the 550 employees the lab laid off — representing more than 10% of the workforce.

It was the fourth round of layoffs in two years at the lab, which has struggled since Congress pulled funding for its flagship Mars Sample Return mission because of a ballooning budget and timeline.

Morale has tanked amid reports of management problems. Staffers say they’re following budget discussions in the national news while hearing little from the lab’s leaders.

“There’s been this creeping dread in anticipation,” said the mechanical engineer, who spoke on condition of anonymity to share her views candidly. “The boot was once again raised to stomp on us, but we didn’t know when it was going to drop.”

As a result, an institution with an illustrious record of solving the hardest problems in space now faces a daunting task here on Earth: reclaiming its place at the vanguard of exploration and innovation.

“People forget how much JPL is known internationally,” said Fraser MacDonald, senior lecturer in historical geography at the University of Edinburgh in Scotland and author of the book “Escape From Earth,” about JPL’s founders. To MacDonald, the lab is “a major scientific and technological anchor in Southern California.”

JPL — which is operated by Caltech in La Cañada Flintridge and funded primarily through NASA — was born in the 1940s, after experiments by Caltech rocket scientists caught the eye of the U.S. military.

Many of the tales of their early endeavors — including a 1936 test that ended with an oxygen line catching fire, creating, essentially, a flailing flame thrower — are now told in hyperbole, MacDonald noted. Regardless, they formed a “quintessentially Californian story,” he said, which helped fuel worldwide admiration.

After World War II, JPL was largely sidelined from the military’s rocketry endeavors, as the U.S. instead focused on a secret mission to bring Nazi scientists into the country to advance rocket development. But when the Cold War propelled the U.S. to seek technological dominance on Earth and beyond, it was JPL that developed the U.S.’ first successful satellite, Explorer 1, designed to study cosmic rays.

The same year, 1958, the U.S. government created NASA, and JPL found a new home.

Contracts for ambitious, high-profile NASA missions have become JPL’s lifeblood. But in recent years, there have been fewer of these to go around.

The White House and Congress — under both Presidents Biden and Trump — have increasingly focused on human spaceflight to the moon and Mars. Meanwhile, mission costs have risen because of economic factors ranging from supply chain expenses to employee cost of living, said Casey Dreier, chief of space policy at the Planetary Society, a space science advocacy organization led by Bill Nye.

At the same time, a series of well-documented recent management stumbles have not helped JPL’s cause.

After NASA’s Psyche mission to a metal-rich asteroid failed to meet its 2022 launch date, the agency commissioned an independent review, which found that internal reorganizations and personnel changes created distracted and uninformed managers and burned-out, stretched-thin staffers.

And, in 2023, another sobering independent review determined there was “near zero probability” of Mars Sample Return making its proposed 2028 launch date, and “no credible” way to fulfill the mission within its budget.

NASA sharply cut its spending on Mars Sample Return in anticipation of budget cuts from Congress — which, by extension, meant steep funding cuts to JPL. The agency eventually began seeking alternative plans from other NASA centers and the private sector, placing JPL in the humbling position of having to compete for its own project.

JPL had beefed up staffing from roughly 5,000 people in the early 2010s to roughly 6,500 to support its flagship missions including Europa Clipper, which is set to explore one of Jupiter’s moons, and Mars Sample Return. But with both Clipper and Psyche now in space and Mars Sample Return shelved, the lab couldn’t find roles for some of the projects’ workers.

“I struggled with balancing the passion that I had for the work with the knowledge that I could be moved off of projects anytime,” said the mechanical engineer, who said that JPLers don’t join the lab for the paycheck. “Why should I pour my heart and soul into it? … A lot of the stuff that we’re doing might never go anywhere. We’re just going to pack it up in boxes and put it on shelves.”

Then came the layoffs for which many had already braced.

In January 2024, the lab let go of 100 on-site contractors. A month later, 530 employees and 40 contractors. When it became clear NASA’s funding for JPL would not substantively change in 2025, the lab laid off an additional 325 employees.

JPL’s 2026 budget is still uncertain, with the government in its third week of a shutdown. But, regardless of which version of the budget Congress passes, the lab probably won’t see any significant new streams of cash.

That could explain why JPL — which says its latest layoffs are not due to the shutdown itself — chose October to send out the layoff notices.

Throughout the two years of steady layoffs — which, all in all, eliminated roughly a quarter of all staff — employees would pepper lab leaders with the same questions at town halls: When were layoffs happening and who was going to be let go? They received few answers.

The JPL Reddit forum, which had historically been a place for aspiring engineers and scientists to ask employees about getting hired and about life at the lab, turned sour. Employees vented their frustrations and posted layoff information that leaders wouldn’t share.

“The morale at JPL is horrid right now,” the mechanical engineer said. “There is a lot of distrust and dissatisfaction that’s been built up against the people who are at the top of decision making on lab.”

Yet, she still sees hope for Southern California’s premiere planetary science lab: “I do genuinely believe that JPL can weather the storm.”

This is not the first time JPL has faced a funding crisis.

In 1981, President Reagan’s administration proposed slashing NASA’s planetary science funding.

NASA’s administrator at the time responded that the cuts would make JPL “surplus to our needs.” JPL seriously considered returning to its origins by pivoting to Department of Defense work, but politically connected Caltech leaders managed to convince Congress and the White House to keep funding Galileo, JPL’s flagship mission at the time to explore Jupiter’s atmosphere.

Few have hope that Mars Sample Return will spur recovery as Galileo did. Dreier, for example, sees a different set of options for the lab in 2025: increasingly rely on defense and national security projects, and use its robotics and Mars expertise to support NASA’s new goal of landing humans on the moon and Mars.

“Who else has landed on Mars as many times as JPL has?” Dreier said. (Answer: No one. JPL has done it successfully nine times since 1976. In fact, a successful landing without JPL didn’t happen until China pulled it off in 2021.)

Saving JPL’s signature planetary science missions like the Mars rovers and Jupiter orbiters is more challenging. Unlike in 1981, the current proposals to cut government spending on science reach far beyond NASA.

And while human spaceflight to our nearby celestial neighbors is certainly a reasonable endeavor, Dreier said, “the cosmos is a lot bigger than just the moon and Mars.”