On September 27, the CDC, in conjunction with the National Foundation for Infectious Diseases and other public health and medical groups, kicked off the 2018-2019 influenza campaign. During the conference, the CDC and its partners emphasized the importance of vaccination in reducing the risk of influenza illness and the potentially deadly complications that it can cause, particularly in light of last year’s “record breaking” influenza season. In this week’s blog post, we will look at the perpetual challenge of poor influenza vaccination coverage, and whether certain technological interventions may be able to help.

2017-2018 Influenza Season

The 2017-2018 influenza season, which was predominantly caused by influenza A(H3N2) and influenza B strains, hospitalized an estimated 900,000 people and killed more than 80,000, including 180 children, in the United States. To put this in perspective, the influenza season with the second-highest number of influenza-associated deaths was in 2012-2013, with 56,000 deaths estimated. Using a new methodology to determine epidemic severity, the CDC classified the 2017-2018 flu season as “high” severity across all age groups--- marking the only time a single influenza season has been considered highly severe across all age categories since the start of CDC’s efforts to measure severity in 2003-2004. The 2017-2018 influenza-like illness (ILI) activity started to increase in November 2017, continued at high rates into January and February, and remained extended into March of 2018. Consequently, the 2017-2018 flu season was one of the longest flu seasons in recent US history.


Influenza vaccination has been lauded as the most important component in reducing community influenza transmission and its downstream consequences. For example, during the 2016-2017 influenza season, use of the vaccine prevented an estimated 5.3 million illnesses and 85,000 hospitalizations. A CDC study that analyzed influenza-associated pediatric deaths from 2010-2014 found that vaccine efficacy against death was 65% among healthy children and 51% among high-risk children. Additionally, studies have indicated that influenza vaccination can reduce the severity of illness for those who do acquire the disease.

Despite the severity of the 2017-18 season, the extent of illnesses and deaths would likely have been notably worse had it not been for the seasonal influenza vaccine, which had an estimated vaccine effectiveness of 40%. While the benefits of vaccination have been widely publicized by public health stakeholders, including CDC, vaccination rates remain consistently low in the United States. Only about 39% of adults were vaccinated by early November 2017, about 3.7% lower than during the same time the previous year. Estimates of vaccine coverage of children (6 mos to 17 years) across the entire flu season found that 58% of children received at least one dose, a 1.1% decrease from the previous year.

Low vaccination coverage is not just present across the general population—low vaccination coverage among rising public health professionals and health care workers (HCW) also pose a challenge. A survey among 158 undergraduate public health students in California found that while nearly 90% were encouraged to get seasonal influenza vaccinations, only 43% reported getting vaccinated. A separate study reported that vaccination among HCW tends to be higher than the national average; however, among settings where HCW are not required or explicitly encouraged to get vaccinated, only around 46% reported being vaccinated during the 2016-2017 season.  Reasons cited for vaccine refusal range from misperceptions about influenza vaccinations to lack of awareness about the potential severity of flu. For example, in the study surveying public health students, about half of those who refused vaccinated incorrectly believed that the vaccine could give them the flu, about 30% thought the vaccine had dangerous side effects, and almost 30% believed they were not at risk of getting the flu.

While reliable sources such as the CDC and news media have published statements or articles to counter such misinformation, misconceptions and lack of awareness surrounding the vaccine persist. Some vaccine-related misperceptions can extend beyond flu to other vaccines as well, posing a substantial long term threat to public health, as demonstrated by increased outbreaks of other vaccine preventable diseases. Continued efforts and resources will be needed to combat these misconceptions both among healthcare professionals and the lay public.

Benefits of new technologies?

The reasons for lack of influenza vaccine uptake are varied and complex. Furthermore, historically low influenza vaccination coverage illustrates the limits of more traditional public health messaging in encouraging people to get vaccinated. Could harnessing technologies help improve coverage rates? Modern technology has been used in the past for purposes ranging from improving vaccination rates by using SMS alerts and vaccine delivery drones, to using internet searches for monitoring epidemics; however, sometimes these technological approaches fall short of expected goals. This year, members of the Seattle Children’s Hospital and Boston Children’s Hospital worked with Amazon to develop an Amazon Echo “Flu Doctor” application. The goal of the application (or “skill”) is to provide increased access to information about the flu to users and to encourage seasonal flu vaccination. The evidence base for this application was developed by a reputable team of experts at the CDC, American Academy of Pediatrics, and Washington State Department of Health.

While this technology has yet to be used and evaluated on a wide scale, the hope is that a more personalized format would encourage people to seek vaccinations in more innovative and compelling ways than what past public health messaging could accomplish. Only the challenge of the upcoming and future influenza seasons will be able to truly put tools like this to the test.

Photo: CDC Deputy Director Anne Schuchat receiving seasonal flu vaccination. Photo courtesy of CDC/Lauren Bishop.

Outbreak Observatory aims to collect information on challenges and solutions associated with outbreak response and share it broadly to allow others to learn from these experiences in order to improve global outbreak response capabilities.