Influenza claimed 50 more young lives in California this week, proving that a potent virus that arrived a virtual stranger in 2009 has gained the lead role in our winter dance with the disease.
The H1N1 virus -- the swine flu bug -- is circulating through susceptible groups, especially among a younger generation that often goes without vaccinations and had not been exposed to this strain, health authorities said Friday.
H1N1 has largely replaced last year's H3N2 strain and has already killed nearly 40 percent more people than last year's total, even though flu season has yet to reach its peak.
In California, it has claimed the lives of 95 adults younger than 65, and 51 more deaths await confirmation as flu related. That would bring the total to 146 deaths, state epidemiologist Dr. Gil Chavez reported at a Friday news conference. The nine Bay Area counties and Santa Cruz County have reported 32 flu-related deaths this season.
That's a pattern similar to what was seen when H1N1 last circled the globe.
"The elderly, like in 2009, are not overwhelmingly getting infected," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. "They are seemingly protected from it."
In contrast, at this time last year, H3N2 dominated and killed many elders -- but only nine deaths were reported among Californians under 65.
The state does not track flu deaths for residents over 65, so information about the impact on that age group is mostly anecdotal.
Among this year's victims were 23-year-old Matthew Walker, of Santa Rosa, a healthy young man who enjoyed windsurfing and skateboarding. The experience of losing a son, his father, Cliff Walker, told NBC Bay Area, was "a ragged roller coaster ride, with a bad ending."
All but one of this year's deaths have been linked to the H1N1 virus. Most occurred in Californians who, unlike Walker, had a pre-existing medical condition, such as chronic heart disease, asthma or a suppressed immune system, or were pregnant, according to Chavez.
One of the newly reported deaths was a child who lived in Riverside County. In all, the illness has claimed the lives of three children under age 10, including one in San Mateo County.
Despite such tragedies, the good news is that H1N1 is less deadly than it was during the peak of the 2009 pandemic, and that is because we're better protected, Fauci said. It is one of the strains included in the current flu vaccine, which usually shields people exposed to the virus. And many who have been sick before have developed antibodies to it.
There are several reasons why younger people seem so vulnerable. Significantly, as a group, they are less likely to be vaccinated than elders.
Some scientists think the genetic structure of H1N1 targets the lungs, while H3N2 tended to attack the upper respiratory system. A mutation in an amino acid called D225G might allow H1N1 to bind more effectively to lung cells, making us more susceptible to pneumonia and death.
And younger people may have not acquired immunity through previous exposure. Forms of the H1N1 virus were detected in the 1930s, then in the mid-1950s and again in 1971, according to flu tracker and biomedical researcher Henry Niman of the Pennsylvania company Recombinomics, Inc. It appeared again -- in significantly altered form -- in 2009.
This year, more than 95 percent of the circulating flu viruses are H1N1, according to the U.S. Centers for Disease Control and Prevention That's much higher than in any of the previous three flu seasons.
"It has knocked the other strains off the map," said Fauci.
It is here to stay, he said. "It's not a pandemic any more. It is a familiar virus," said Fauci.
"It's ours now. We own it."
Contact Lisa M. Krieger at 650-492-4098.
PREVENTING AND TREATING THE FLU
We tend to take flu for granted: It keeps us home with fever and headache, coughs and a dripping nose. But the illness can kill, and it's not through with us yet.
"We think the peak is still yet to come. We think we have still not seen the worst of it yet," said Dr. Yvonne Maldonado, chief of pediatric infectious disease at Lucile Packard Children's Hospital Stanford and a professor at the Stanford School of Medicine.
Here is her advice:
How do I know I'm sick with the flu and not just a cold?
Symptoms of a cold tend to be limited to your respiratory system, causing a runny nose, sneezing and coughing, but rarely a fever. In contrast, the flu involves your whole body. Flu symptoms include an abrupt onset of chills, fever (often above 101°F), headache, muscle aches and general malaise. People with influenza may also have a sore throat and often develop a cough.
How do I treat it?
Stay home from work or school and avoid other public places. Rest, drink plenty of fluids and take acetaminophen or ibuprofen for fever and muscle aches.
Is it too late to get the vaccine?
No. "It's never too late for children and adults to get a flu shot," Maldonado said. Vaccination prevents serious illness, and it keeps the flu from spreading to others. The vaccine takes about two weeks to become fully effective, so get it as soon as possible.
Where do I get the vaccine?
Call your health care provider or go to http://flushot.healthmap.org to find the nearest supplier.
When to SEEK Emergency HELP
Seek medical attention if children show any of the following symptoms:
High or prolonged fever for more than four to five days; fast breathing, labored breathing or trouble breathing; bluish skin color, especially around the lips or fingers; not drinking enough fluids; changes in mental status, somnolence, irritability, confusion or lethargy; influenza-like symptoms improve but then return with fever and worse cough; worsening of underlying chronic medical conditions (for example, heart or lung disease, diabetes); severe or persistent vomiting (more than three to four times in 24 hours); cough produces yellow sputum.
Adults should seek medical attention for any of the following:
High or prolonged fever for more than four to five days; difficulty breathing or shortness of breath; cough becomes productive of yellow sputum; pain or pressure in the chest; near-fainting or fainting; dizziness or lightheadedness with standing; confusion or altered level of consciousness (not acting normally); severe or persistent vomiting (more than three to four times in 24 hours).
Source: Stanford Hospital & Clinics and Lucile Packard Children's Hospital at Stanford
Bay Area flu deaths
Alameda County: 4
Contra Costa County: 5
Marin County: 2
Napa County: 1
San Francisco County: 2
San Mateo County: 4
Santa Clara County: 8
* Santa Cruz County: 1
Solano County: 1
Sonoma County: 4
* Santa Cruz County is outside the official nine Bay Area counties.