US Pediatric Flu Vaccinations Decreased in 2020

A CDC analysis shows more doses were administered adults and adolescents than in previous years, while COVID-19 factors may have influenced the dip in shots among children.

Despite an overall uptick in influenza vaccinations during the 2020-21 season, pediatric vaccination against the flu remains underwhelming in the US.

A new analysis of 11 national jurisdictions with relevant flu vaccination data for last year shows that administered doses for children aged 6 months to 4 years old in September-December 2020 actually declined from the previous 2 years, despite heightened awareness campaigns and advocacy for immunization against influenza during surging new COVID-19 cases.

The data from investigators at the Centers for Disease Control and Prevention (CDC) reinforce the need for education and awareness campaigns on the availability and recommendation of flu vaccination in children as young as 6 months old—especially headed into another winter season with COVID-19 outbreak risks.

Led by Patricia Castro Roman, MPH, the CDC investigators sought to interpret the percentage change between administration of ≥1 flu vaccine dose during the first half of last year’s flu season, compared with averages from the corresponding periods in 2018 and 2019. The team used data from 11 US jurisdictions with high-performing state immunization information systems.

Roman and colleagues believed this finding would provide a more clear understanding of how COVID-19 impacted influenza vaccination coverage in the US. As they noted, approximately 9 to 41 million annual flu cases occurred between 2010 and 2020; up to 52,000 persons have died each year from the preventable virus.

“As the United States enters the 2021–22 influenza season, the potential impact of influenza illnesses is of concern given that influenza season will again coincide with the ongoing COVID-19 pandemic, which could further strain overburdened health care systems,” they wrote.

Investigators stratified jurisdiction data reported to the CDC by vaccinated patient age groups:

  • 6-23 months
  • 2-4 years
  • 5-12 years
  • 13-17 years
  • 18-49 years
  • 50-64 years
  • ≥65 years

The team observed 16,872,970 flu vaccine doses administered in the 11 study jurisdictions in September-December 2020. Comparatively, a mean 15,513,428 doses were reported in the same time period and jurisdictions in 2018 and 2019—indicating a 9% increase in flu doses in 2020 across all age groups versus the last 2 years.

Among children aged 6-24 months and 2-4 years, however, flu vaccine administration decreased 13.9% and 11.9%, respectively. Doses administered to children aged 5-12 years stayed consistent in 2020 as to averages reported for 2018 and 2019. Interestingly, doses administered to adolescents aged 13-17 years increased by 12.9% in 2020—the lone pediatric age group to report an increase in flu vaccination during COVID-19.

Each adult age group reported a significant increase in flu vaccinations in 2020 versus 2018 and 2019; persons aged 50-64 years increased by 15.3%; persons aged 18-49 years increased 14.6%; and persons aged ≥65 years increased 9.5%.

Roman and colleagues noted the findings are consistent with a national survey data assessment from this year that showed that influenza vaccination coverage was lower among persons aged 6 months to 17 years than in adults aged ≥18 years during the 2020-21 flu season, compared to the previous year.

The factors influencing this dip in pediatric vaccination, such as immunization awareness campaigns, remains unclear to investigators.

“These campaigns emphasized the importance of receiving the annual influenza vaccine to help reduce the spread of influenza viruses,” they wrote. “Although the flu vaccine does not protect against COVID-19, influenza vaccination was part of a public health strategy to flatten the curve of respiratory illnesses overall, protect essential workers from influenza, and preserve medical resources for care of COVID-19 patients.”

As they noted, the 2020-21 flu season was atypically minimal in the US; the implementation of public health measures against COVID-19, such as face-masking, social distancing, and remote working and education, most likely mitigated the effect of the flu. But the experts now worry that the effect of these measures may have misled parents to believe their children are at lower risk of contracting influenza.

Parents may have also been impacted by barriers to health and flu vaccination brought on by the pandemic. But now that COVID-19 vaccinations and therapies have progressed a gradual lift of public health mandates and practices, children are likely again at a heightened risk of flu this season.

“Influenza vaccination in 2020 was part of a comprehensive public health strategy to reduce the prevalence of respiratory illnesses overall, to help protect essential workers from influenza, and preserve medical resources for patients with COVID-19,” they concluded. “Influenza vaccination among all age groups could help reduce the spread of influenza this fall and winter, and reduce the potential burden that influenza cases could place on health care systems already overburdened by COVID-19.”

The study, “Influenza Vaccinations During the COVID-19 Pandemic — 11 U.S. Jurisdictions, September-December 2020,” was published in Morbidity and Mortality Weekly Report.