Many worry about efficacy

Vaccine hesitancy is a growing concern among public health officials and a report detailing parental hesitancy about seasonal flu vaccine may be especailly worrisome amidst the Covid-19 pandemic. First published June 15, 2020, the analysis found that as many as 25% of parents expressed doubts about the flu vaccine. As the nation rolls out vaccines for Covid-19, BreakingMED is republishing this throughtful analysis as part of its year-end clinical review series.

When asked if they planned to have their children receive flu vaccine, just over 1 in 4 U.S. parents expressed hesitancy and close to 1 in 15 have doubts about routine childhood vaccines.

Roughly 1 in 8 parents expressed concern about the safety of both routine childhood and influenza vaccines, and just 1 in 4 said they believed the influenza vaccine was effective.

Findings from the World Health Organization (WHO) devised survey, published online June 15 in the journal Pediatrics, represent the first national snapshot of parental immunization hesitancy, the researchers noted.

Many previous assessments of childhood vaccine attitudes among parents have utilized the Parent Attitudes about Childhood Vaccines (PACV) scale, developed and validated in mostly higher-income subjects in Washington State, wrote researcher Allison Kempe, MD, of Children’s Hospital Colorado in Aurora, and colleagues.

Data on parental attitudes nationally toward childhood vaccines have been limited.

Annual flu shots are recommended for all children and teens in the U.S. over the age of 6 months, but the rate of vaccination in the 2016-2017 flu season was just under 60%, according to the CDC.

“In our data, it is shown that hesitancy for influenza vaccination was more than 4 times higher than for routine childhood vaccines, and, importantly, the factors driving hesitancy differed,” Kempe and colleagues wrote. “Concerns about serious side effects were similar, but concerns about many other factors were much higher for influenza vaccine, especially concerns about effectiveness.”

The survey also revealed higher rates of hesitancy for both childhood and influenza vaccines among parents with lower education (less than a bachelor’s degree) and lower household incomes.

In the newly published study, the researchers surveyed families with children between the ages of 6 months and 18 years early in 2019, using the online, nationally representative Ipsos panel, which is the largest Internet-based survey panel in the U.S.

After weighting, they assessed hesitancy using a modified, validated WHO Vaccine Hesitancy Scale and labeled parents as hesitant if they scored 3 or greater.

The survey questions were designed to assess whether concerns about either routine childhood or influenza vaccines had led the parent to defer or refuse vaccines for their children.

Just under half (2,176 of 4445) of parents sampled completed the survey (response rate 49%).

Among the main findings:

  • Hesitancy prevalence was 6.1% for routine childhood and 25.8% for influenza vaccines; 12% of respondents strongly agreed and 27% somewhat agreed they had concerns about serious side effects of both routine childhood and influenza vaccines.
  • When asked if “all childhood vaccines offered by my child’s health care provider are beneficial,” 55% of respondents strongly agreed, 32% somewhat agreed, 10% somewhat disagreed and 3% strongly disagreed.
  • When asked to respond to the statement “I do what my child’s health care provider recommends about flu vaccines,” 40% of respondents strongly agreed, 33% somewhat agreed, 18% somewhat disagreed and 9% strongly disagreed.
  • A total of 70% strongly agreed that routine childhood vaccines are effective versus 26% for influenza vaccine (P<0.001).
  • In multivariable models, an educational level lower than a bachelor’s degree and household income <400% of the federal poverty level predicted hesitancy about both routine childhood and influenza vaccines.

Kempe and colleagues hypothesized that the relatively high hesitancy of parents regarding yearly vaccinations for the flu may be due, in part, to reports of low vaccine effectiveness from surveillance networks and the withdrawal of live attenuated vaccine due to poor effectiveness several years ago. In an editorial published with the study, Annabelle de St. Maurice, MD, of the University of California, Los Angeles and Kathryn Edwards, MD, of Vanderbilt University, Nashville, wrote that efforts aimed at reducing parental skepticism about influenza vaccination should focus on the burden of influenza in children, as well as “re-branding influenza vaccine as a ’routine’ childhood immunization, reassurance on influenza vaccine safety and discussion of the efficacy of preventing influenza vaccine in preventing severe disease.”

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“Unaware of the burden of disease and severity, parents may dismiss influenza vaccination,” they wrote. “However, influenza causes severe disease in children, with high rates of outpatient visits and hospitalizations.”

They noted that in the 2017-2018 influenza season and the current 2019-2020 season, 188 and 169 pediatric deaths related to flu were reported.

And they added that “overwhelming evidence” demonstrates that flu vaccines are safe, with nearly 170 million vaccine doses safely given during the 2018-2019 season.

They urged health providers to reassure parents concerned about flu vaccine safety and educate them on the impact of vaccination on preventing hospitalization, severe illness and death.

“When reports of vaccine efficacy are released each year, these data should be taken within the context of preventing severe illness rather than simply commenting on the matching of circulating influenza strains,” they wrote. “Even in the years when there is a poor match, the vaccine is impactful.”

St. Maurice and Edwards cited figures from the 2017-2018 influenza season, in which the overall vaccine effectiveness was just 38%. Despite this, vaccination was estimated to have prevented 109,000 hospitalizations and 41% of expected hospitalizations among very young children in the U.S.

“The results of this survey suggest that when communicating about flu vaccine, it is important to remind parents that flu can be severe in children and to highlight the efficacy and safety of flu vaccine,” they concluded. “Although researchers continue to work to improve the efficacy of influenza vaccines, vaccines remain a powerful tool to prevent influenza.”

Salynn Boyles, Contributing Writer, BreakingMED™

Funding for this research was provided by the National Institute of Allergy and Infectious Diseases.

Researcher Gregory Zimet reported receiving honorarium from Sanofi Pasteur for work on the Adolescent Immunization Initiative and consulting fees and travel support from Merck. Researcher Sharon Humiston reported receiving honorarium from Sanofi Pasteur for work on the Clinical Immunization Collaborative Virtual Advisory Board.

Editorial co-author Kathryn Edwards reported serving as a consultant for Merck, Bionet, and International Business Machines; and membership on data safety and monitoring boards for Sanofi, X4 Pharmaceuticals, Seqirus, Mederna and Pfizer.

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