"It's not a very good match for B/Victoria", said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, referring to the strain.
Although it doesn't appear to be the best match for Influenza B/Victoria, Dr. Fauci said the vaccine is "a really good match" for the strain called H1N1.
Two children have died in Douglas County, according to the department.
The biggest takeaway here is that this year's flu shot isn't a great match for the leading virus out there right now: B/Victoria-in fact, it's the first time in 27 years that an influenza B virus has dominated the flu season so early on.
Another issue regarding the flu vaccine and its partial ineffectiveness for B/Victoria?
Fauci said although it's not a good match for the strain.
Health officials say an average of 46 South Dakotans die every year following flu infections.
Flu shots are still effective, county officials say, and those who get a shot now but still get the flu will most likely have more mild symptoms and less risk of serious complications.
And even though it is best to get vaccinated before the end of October, getting vaccinated once the flu season is upon us is still better than not getting vaccinated at all.
The county agency issued an advisory on January 8 warning residents that the flu season had not yet peaked and urging people to take appropriate precautions.
Shots are available at many local pharmacies or at county Public Health Department clinics.