Despite studies citing protection, flu vaccination is down among children in the United States so far this winter, according to the Centers for Disease Control and Prevention. File photo by Roger L. Wollenberg/UPI | License Photo
Jan. 13 (UPI) -- Fewer children and teens age 17 years and younger have been vaccinated against the flu this winter compared with the 2020-21 winter season, the Centers for Disease Control and Prevention said Thursday.
Vaccination rates among young people eligible for the vaccine -- those ages 6 months to 17 years -- are down 5% from the 2020-21, agency data showed.
This means fewer than half, or 46%, of people in this age group nationally have been vaccinated against the seasonal virus, the CDC said.
Through the end of December, flu vaccination rates for all age groups were down 11% for this winter compared with last winter, when the CDC and others urged people in the United States to obtain the shot to prevent a spike in illnesses during the COVID-19 pandemic.
In a typical flu season, more than 30,000 people across the country are sickened with the virus and 380,000 people are hospitalized as a result, according to the CDC.
However, the flu vaccine, which is formulated annually based on strains of the virus believed to be in circulation, protects against serious illness up to 60% of the time, agency data indicates.
A study led by CDC researchers and published Thursday by Clinical Infectious Diseases, found that the 2019-20 vaccine reduced the risk for severe flu in children by 78% against strains covered by the shot and by 47% against other, similar strains.
In addition, the 2019-20 vaccine was 76% effective at preventing life-threatening illness from the flu, including the need invasive mechanical ventilation to breathe and other severe complications as well as death, the CDC researchers said.
"This study highlights that flu can cause serious illness in children, but flu vaccines can be lifesaving," CDC Director Dr. Rochelle P. Walensky said in a statement.
"It's especially important that children get a flu vaccine in addition to their recommended COVID-19 vaccines this season," she said.
The CDC has not provided estimates of flu cases nationally so far this winter, though data suggests illnesses from the seasonal virus are down significantly, due at least in part to mask-wearing and social distancing measures to prevent COVID-19 spread.
Both are respiratory viruses that spread via airborne droplets emitted from the nose of mouth of those infected, according to the agency.
Still, fewer than 10,000 people across the country have been hospitalized with confirmed influenza infection so far this winter, and two children have died from the virus, at least through Jan. 7, the CDC said.
Like all viruses, the flu evolves as it circulates, including as part of a process called antigenic drift, which allows it to escape the protection offered by vaccines, the anency.
Each year, how effectively the flu vaccine protects against infection is determined in part by the similarity between the viruses chosen for vaccine production and viruses circulating in the community, it said.
Although the composition of flu vaccines is reviewed annually and updated to match evolving viruses, changes in the virus can still outpace vaccine production, the agency said.
Several flu strains circulate in a typical season, and vaccines are designed to protect against four of them.
Flu season has started in many parts of the country, with continued flu activity expected over the coming weeks, according to the CDC.
To date, most cases in children and young adults have involved H3N2 strain of the virus, which are genetically closely related to the H3N2 vaccine virus but have some differences that may result in reduced protection from the vaccine, the agency said.
However, vaccination still can have "important benefits," offering nearly 50% protection against serious illness, even when this occurs, the CDC said.
The virus can be especially dangerous for children age 5 years and younger because they are at higher risk of getting very sick, according to the agency.
For the new CDC-led study, researchers looked at data from the 2019-2020 flu season, during which a record-breaking 199 flu deaths in children were reported to the agency.
During that season, most flu cases were caused by two viruses that were antigenically different from their corresponding vaccine viruses, the researchers said.
They compared the effectiveness of the vaccine against these strains as well as those included in the formulation and in 132 healthy children and 159 who suffered serious illness from the virus, they said.
"Flu season has started and currently flu vaccination is down in children," Walensky said in the statement.
"So now is the best time to get your child vaccinated, if you have not already," she said.