The flu season has taken a turn for the worse in the Bay Area. New figures show the number of flu-related deaths in the region is now up to four.
Health officials say this year's flu vaccine is doing a pretty crummy job. It's only 23 percent effective, which is one of the worst performances in the last decade, according to a government study released Thursday.
The poor showing is primarily because the vaccine doesn't include the bug that is making most people sick, health officials say. In the last decade, flu vaccines at their best were 50 to 60 percent effective.
Bay Area health officials are seeing increased flu activity and are encouraging residents to get flu shots and wash their hands.
Last week, the California Department of Public Health announced the state’s first flu death in Southern California. So far this season, the Bay Area has seen four flu deaths in adults living in San Francisco, San Mateo and Sonoma counties.
Only flu deaths in people under age 65 are reported to public health departments.
“Although Ebola has gotten a lot of attention recently, flu is a much more real threat here in the Bay Area,” said George Han, deputy health officer of Santa Clara County. “Every year, flu sickens and kills thousands of Americans and is particularly dangerous to the young, elderly and those with chronic illnesses or weakened immune systems.”
Influenza A H3N2 viruses have been most common so far this season.
In comparison, in the 2012-2013, 2007-2008, and 2003-2004 seasons, H3N2 strains predominated and were associated with the highest seasonal flu mortality levels of the past decade. About two-thirds of this year’s H3N2 viruses that have been analyzed show changes that may make this year’s flu shot less effective at protecting against this particular strain.
Depending on how it is formulated, flu vaccines protect against three or four different flu viruses. Even during a season when the vaccine is only partially protective against one flu virus, it can protect against the others.
“Even though this year’s flu vaccine is not a perfect match for all of this year’s flu viruses, it is still worth getting,” said Dr. Han. “The vaccine will still protect against other strains of flu that are circulating, and can decrease the severity of illness if you do get sick.”
"This is an uncommon year," said Dr. Alicia Fry, a flu vaccine expert at the Atlanta-based Centers for Disease Control and Prevention, who was involved in the government study.
The findings are not surprising, though. In early December, CDC officials warned the vaccine probably wouldn't work very well because it isn't well matched to a strain that's been spreading widely.
Local
Each year, the flu vaccine is reformulated, based on experts' best guess at which three or four strains will be the biggest problem. Those decisions are usually made in February, months before the flu season, to give companies that make flu shots and nasal spray vaccine enough time to make enough doses.
But this year's formula didn't include the strain of H3N2 virus that ended up causing about two-thirds of the illnesses this winter. And that strain tends to cause more hospitalizations and deaths, particularly in the elderly, making this a particularly bad winter to have a problem with the flu vaccine.
Indeed, the flu season is shaping up to a bad one. Health officials are comparing it to the nasty flu season two winters ago, and this one may prove to be worse. Hospitalization rates in people 65 and older are higher than they were at the same point in the 2012-2013 season, according to CDC data.
The results from the preliminary study weren't large enough to show how the vaccine is working in each age group, although flu vaccines traditionally don't work as well in elderly people.
The study involved 2,321 people in five states - Michigan, Pennsylvania, Texas, Wisconsin and Washington - who had respiratory illnesses from November to early January. The researchers said vaccinated people had a 23 percent lower chance of winding up at the doctor with the flu.
The CDC began regularly tracking the effectiveness of the flu vaccine during the 2004-2005 season, but the results for the first few years were from smaller studies and are considered less reliable. Effectiveness has ranged from 47 percent to 60 percent in the last half-dozen years, when studies involved larger numbers of patients.
It's only in those last several years that "we really understand what's really going on" with the flu vaccines, said Dr. Arnold Monto, a University of Michigan flu expert and another author of the study.
In addition to getting vaccinated, it's important to practice good hand washing and health habits, and avoid touching your eyes, nose and mouth. For more information about influenza, visit www.flu.gov or www.sccphd.org.
People who are ill can help stop the spread of germs:
- Limit contact with others – stay home from work or school
- Cough or sneeze into your elbow or sleeve, not into your hands
- Wash hands thoroughly with soap and water, or use an alcohol-based rub
