The total number of lab-confirmed influenza cases and the percentage of emergency department visits for flu-related symptoms all went up in the past week, according to the San Diego County Health and Human Services Agency.
Every year the flu virus changes, producing different strains and forcing our bodies to adapt in order to fight the virus.
Overall, its effectiveness reached 48 percent. One study found this type of vaccine was 63 percent more effective than regular-dose unadjuvanted flu shots in persons over the age of 65. Of those who tested positive for influenza, 88% of those viruses were influenza A and 12% were influenza B. Among influenza A viruses, 98% were A (H3N2) viruses. Scientists have identified almost 600 variations of the virus this season.
To prevent the spread of the flu, frequent and thorough handwashing is the most important step. According to a CDC study, early treatment could cut the duration of a hospital stay for older adults and reduce their risk of needing extended care after discharge. There have been 20 pediatric deaths reported so far this season.
While most should get vaccinated, those with generally weaker immune systems are especially at risk - usually small children and seniors. "Activity is increasing in some of the Midwest and the East Coast".
Thus, "elevated influenza activity in parts of the United States is expected for several more weeks", according to the report, which was published today (Feb. 16) in the CDC journal Morbidity and Mortality Weekly Report.
She said insurance providers also have information on where the vaccine is available.
In the last H3N2-dominant flu season, in 2014-15, the target virus in the vaccine was not well matched to the viruses that were making people sick. "It will protect you for the rest of the season".
"So, there are a lot of hospitalizations and deaths prevented when the vaccine is not as flawless as we would like", he noted. "It's a big number for what is a moderate level of vaccine effectiveness", he said.
Most influenza vaccine is produced in hen's eggs; the viruses have to adapt to grow in eggs.
Often times the common cold is mistaken for the flu. "The flu shot is still the best way to make sure you and your loved ones are protected".
"So half a loaf is better than none", said Schaffner. A really stellar vaccine year would see an effectiveness of about 60 percent, he said.
"But for H3N2, it's as good as we have seen for some of the H3N2 seasons that have been well matched".
With flu continuing to occur through this month and into March, there's still flu that can be prevented or made less severe, said Schaffner.
It's not too late to protect yourself and your family.