Early-Season Influenza Vaccination Uptake and Intent Among Adults – United States, September 2020

At a glance

During the 2020-21 influenza season, there were concerns about both influenza and COVID-19 circulating at the same time. To address this, in September 2020, the CDC conducted an internet panel survey to study the early signal of influenza vaccination behavior in the United States during the COVID-19 pandemic in a representative sample of U.S. adults. This report provides a summary of the findings.

Summary

The annual burden of influenza in the United States is significant, leading to 140,000-810,000 hospitalizations and 12,000-61,000 deaths each year since 20101. Influenza vaccination is recommended for all persons aged 6 months and older to prevent influenza infection and reduce the likelihood of severe complications and death2. For the 2020–21 influenza season, concerns about concurrent circulation of influenza and SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), led to increased emphasis on maximizing influenza vaccination coverage in order to reduce the burden of influenza-related respiratory illnesses on the public's health and the health care system. To examine early signals regarding influenza vaccination behavior in the United States during the COVID-19 pandemic, the Centers for Disease Control and Prevention (CDC) conducted an internet panel survey among a representative sample of U.S. adults in September 2020. Among 3,594 respondents, 59.0% had been or intended to be vaccinated during the 2020–21 influenza season compared with 52.2% reporting vaccination any time during the previous season. Intent to be vaccinated was significantly higher among health care personnel (HCP) than non-HCP essential workers (74.2% vs. 57.9%). Among respondents not intending to be vaccinated, reasons given most frequently were not wanting (21.1%) or feeling the need for (16.3%) influenza vaccination; few mentioned risk of COVID-19 exposure in the vaccination setting (5.8%) or that they were already using preventative measures such as masking and social distancing (3.2%). Early-season data do not indicate substantial differences in intended influenza vaccination behavior during the 2020–21 influenza season compared with other recent seasons, although vaccination uptake may ultimately be higher than previous seasons. While flu activity is still low at this time, it may increase in the coming weeks, and public health and medical professionals should reiterate the importance of influenza vaccination during December 2020 and beyond and emphasize the wide availability of vaccine along with safe opportunities to receive influenza vaccination in provider offices and other locations.

Methods

From September 10-October 1, 2020, an Internet panel survey was fielded to a sample of U.S. adults aged ≥18 years who were members of a large, probability-based online panel (KnowledgePanel). The panel is constructed from a random sample of the United States Postal Service Delivery Sequence file, which covers nearly 100% of the U.S. population. Surveys are fielded online in English and Spanish; Internet access is provided to prospective panel members who lack in-home Internet connections. For this survey, non-Hispanic Black and non-Hispanic other or multiple-race panel members were oversampled to ensure adequate sample size for subgroup analyses by respondent race/ethnicity.

Sampled panel members received an email invitation including a survey link and up to 7 email reminders to non-respondents to complete the survey. Beginning on September 19, an additional incentive of $5 was provided to non-responders to reach target completion rates. Of the 5,160 panel members invited to respond, 3,594 completed the survey for a cooperation rate of 69.7%. Data were weighted using demographic benchmarks from the March 2020 Current Population Survey (for age, sex, race/ethnicity, Census region, residence in a Metropolitan Statistical Area, level of education, and household income) and the 2018 American Community Survey (for language proficiency [English or Spanish] among Hispanic respondents) to make respondents representative of the total U.S. population. All analyses were conducted in SAS 9.4 and SAS Enterprise Guide 7.13 (Cary, NC) and SUDAAN (Research Triangle Park, NC).

Certain health conditions confer increased risk of severe complications from influenza infection. Conditions captured in this survey include asthma, chronic bronchitis or COPD; diabetes or pre-diabetes [excluding gestational diabetes]; heart attack, heart disease, or other heart condition; nonalcoholic fatty liver disease; kidney disease; a weakened immune system from a solid organ or blood or bone marrow transplant, immune deficiencies, HIV, use of corticosteroids, or use of other immunocompromising medicines; sickle cell disease; a neurologic condition such as dementia; obesity; or being currently pregnant. Respondents aged 18-64 years reporting diagnosis with ≥1 of these conditions were classified as 'high-risk' in the analyses.

Employment as an essential worker was defined using data on industry category and subcategory reported by respondents; categories followed the North American Industry Classification System (NAICS). Essential workers were broadly identified using the sectors identified by the U.S. Cybersecurity and Infrastructure Security Agency (CISA) as comprising the essential critical infrastructure workforce, although some sectors not included in that list (e.g., persons working in early care and education) were included in the 'essential worker' category for this survey. Health care personnel (HCP) – defined as all respondents reporting currently working in the health care industry – were analyzed separately from all other essential workers.

The primary outcome of interest was intent to receive influenza vaccination during the 2020–21 influenza season. Intent to receive influenza vaccination was defined as reporting already having been vaccinated during the current season or, among the unvaccinated, reporting being "absolutely certain" or "very likely" to receive influenza vaccination before the end of May 2021. Vaccination intent was examined by age group, sex, race/ethnicity, educational attainment, employment as an essential worker, and presence of one or more high-risk medical conditions. Among persons not reporting intent to vaccinate, reasons for non-intent were examined overall and by selected demographic characteristics. Place of vaccination was assessed among all persons reporting being scheduled to receive influenza vaccination as well as among persons who had already received the influenza vaccine as of the time of the survey. Influenza vaccination status and place of vaccination for those who received the vaccine in the 2019-20 season were also collected.

Results

Overall, 59.0% of respondents reported intention to receive influenza vaccination during the 2020–21 influenza season: 12.3% of respondents had already been vaccinated and 46.7% reported being absolutely certain or very likely to receive the vaccine this season. When asked if they had received an influenza vaccine previously, 52.2% reported being vaccinated during the 2019–20 influenza season. By age, intention to vaccinate was highest among adults ≥65 years (75.3%) and lowest among adults aged 18-49 years (50.8%) (Table 1 [XLS – 25 KB]). Intention to vaccinate was highest among non-Hispanic respondents of other races ("other race") (65.4%) and non-Hispanic White ("White") respondents (61.0%); only half of non-Hispanic Black ("Black") respondents (50.8%) and 54.1% of Hispanic or Latino ("Hispanic") respondents reported intent to receive the influenza vaccine. Intention to vaccinate increased with increasing levels of education – from 51.0% among those with a high-school education or less to 75.5% among those with more than a college education. Vaccination intent was higher among respondents reporting any type of health insurance (62.0%) than the uninsured (25.6%), and was higher among those with public (67.6%) than private (59.5%) insurance; similarly, a higher proportion of respondents with public insurance than with private insurance had already received influenza vaccine (17.2% vs. 10.8%). Among respondents with a high-risk medical condition, 64.4% reported vaccination intent compared with 50.4% of respondents without a high-risk medical condition.

Overall, workers identified as essential reported similar intent to receive influenza vaccine (61.4%) compared with persons who were not essential workers (57.7%). Examined by subgroup, intent to vaccinate was highest among HCP (74.2%); non-HCP essential workers (57.9%) and non-essential workers (53.3%) reported similar levels of vaccination intent. Most respondents reporting a health care provider had recommended influenza vaccination to them were intending to be vaccinated (81.1%), compared with only half of those not receiving a provider recommendation (50.4%). Respondents reporting no doctor visit since July 1, 2020 were less likely (49.2%) to report influenza vaccination intent than respondents reporting ≥1 visit; vaccination intent did not differ based on whether in-person (68.8%), telemedicine (70.0%), or both types (63.6%) of visits were reported.

When asked where they had gotten or intended to get vaccinated, similar proportions of respondents selected doctor's offices (37.6%) and stores (37.3%), which include retail pharmacies (Table 2 [XLS – 23 KB]). The distribution of responses for anticipated location of vaccination did not differ notably from that reported for receipt of influenza vaccination during the 2019–20 influenza season. However, among persons who had already received the influenza vaccine during the 2020–21 season, the proportion reporting vaccination at a store (53.8%) was significantly higher than the equivalent proportion for the 2019–20 season (34.9%), and the proportion reporting vaccination at a doctor's office was significantly lower than 2019–20 (29.7% vs 37.3%).

Among respondents not intending to receive the influenza vaccine this season, the most common main reasons given were just not wanting the vaccine (21.1%) and not feeling the need for influenza vaccination (16.3%) (Table 3 [XLS – 19 KB]). Only 5.8% cited risk of COVID-19 exposure in the vaccination settings, and only 3.2% reported that COVID-19 mitigation practices like masking and social distancing obviated the need for influenza vaccination.

Limitations

These findings are subject to at least five limitations. First, this survey measured intent to receive the influenza vaccine during the current season rather than vaccination receipt; respondents' ultimate vaccination behavior may be inconsistent with their reported vaccination intent. Second, although panel recruitment methodology and data weighting were designed to produce nationally representative results, respondents may not be fully representative of the general U.S. adult population. The overall estimate of 2019–20 season influenza vaccination coverage from this survey (52.2%) was higher than the 48.4% estimate from the Behavioral Risk Factor Surveillance System3 . Third, influenza vaccination status and place of vaccination were self-reported and not verified by medical records, so these data might be subject to bias; however, self-reported influenza vaccination status among adults has been shown to be >90% sensitive and >65% specific45. Fourth, high-risk medical conditions were also self-reported and not validated by medical records. Finally, place of vaccination was reported among those already vaccinated or who reported they were scheduled to get vaccinated. For those scheduled to get vaccinated, their planned place of vaccination may not match if and where they ultimately get vaccinated.

Discussion

Overall, results of an early-season survey regarding intent to receive influenza vaccination during the 2020–21 influenza season suggest that the general public did not anticipate substantially changing their typical influenza vaccination behavior as a result of the COVID-19 pandemic. Reported intent to vaccinate in the current season was somewhat higher than reported vaccination coverage during the 2019–20 season, but demographic differences in vaccination intent, planned location of vaccination, and primary reasons for non-vaccination among those not planning to be vaccinated were consistent with findings from previous influenza seasons. Notably, among persons who reported already having received the influenza vaccine, a greater proportion reported vaccination in stores and a smaller proportion reported vaccination in doctors' offices compared with vaccination locations reported for the 2019–20 season.

In the current survey, 59.0% of respondents reported intent to receive influenza vaccination during the 2020–21 influenza season. This is slightly higher than the 52.2% who reported receiving influenza vaccination during the prior season and the 48.4% of U.S. adults who reported influenza vaccination during the 2019–20 season in a larger national survey3. By comparison, findings from a survey with similar methodology conducted in early November 2020 found 49% of adults in the United States had received an influenza vaccine, compared with 44% vaccinated by early November 2019; 35% of survey respondents reported being more likely to get an influenza vaccine this year because of the COVID-19 pandemic, while 11% reported being less likely 6. Findings from the Southern Hemisphere suggest that pandemic mitigation measures like social distancing, mask-wearing, and stay-at-home/shelter-in-place orders substantially reduced the circulation of influenza viruses during their most recent influenza season7; to the extent that such measures continue to be implemented in the United States and influenza circulation is reduced, the benefits of increased influenza vaccination coverage are less clear. Yet, mathematical modeling suggests relatively small increases in influenza vaccination coverage could prevent thousands of influenza-associated hospitalizations even in low-severity seasons 8. Current COVID-19 disease activity and inconsistent adherence to community mitigation procedures across the United States9 suggests influenza circulation is still possible this season; in this case, improvements in influenza vaccination coverage would result in public health benefit. Easing of COVID-19 community mitigation strategies and inconsistent use of personal protective measures has been associated with increased influenza activity and influenza outbreaks in other countries10.

While overall intent to be vaccinated was slightly higher, demographic differences in influenza vaccination intent were largely similar to previously observed differences in influenza vaccination behavior3. Particularly concerning are the disparities in vaccination intent by race/ethnicity: approximately half of Black and Hispanic respondents reported intent to receive influenza vaccination compared with 61% of White respondents and 65% of other-race respondents. Black and Hispanic Americans are disproportionately likely to be hospitalized with influenza11; these populations have also disproportionately suffered the effects of the COVID-19 pandemic 12 Reducing the burden of respiratory illnesses in these populations through seasonal influenza vaccination is a necessary step to prevent compounding the effects of COVID-19 on the health of these populations. CDC is currently working with national and local organizations to address longstanding racial and ethnic disparities in adult influenza vaccination as a preparatory step for implementation of COVID-19 vaccination in communities experiencing health disparities.

The United States is currently experiencing a surge in COVID-19 morbidity and mortality that threatens to exceed resources available to treat severely ill patients in hospitals nationwide13, underscoring the need to mitigate the burden on the health care system by reducing preventable hospitalizations, including those caused by complications of influenza infection. Concerns about potential exposure to COVID-19 in health care settings have resulted in decreased utilization of routine and urgent medical care14; however, results from this survey do not indicate that concerns about exposure to SARS-CoV-2 in vaccination settings was perceived as a major barrier to seeking influenza vaccination among adults in September 2020. The survey found that among adults who reported having already received the influenza vaccine, a higher proportion were vaccinated in retail locations and a lower proportion in doctors' offices compared with the 2019–20 season. The reasons for these differences could not be determined with the data collected; lower proportions of vaccination in physician office settings could be due to concerns about contracting COVID-19, lack of appointment availability (e.g., due to office closures or reductions in hours, lack of adequate vaccine supply), or other reasons.

As the COVID-19 pandemic continues, increasing influenza vaccination coverage among U.S. adults is important to reduce burden on the health care system, avoid exacerbation of existing health inequities among certain racial and ethnic groups, and maintain the public's health. Although influenza activity in the United States is low as of mid-December 2020, it may increase in the coming weeks. Influenza vaccination is the best way to prevent illness and complications caused by influenza, and vaccination is beneficial even when received in January or later 15. A record number of influenza vaccine doses are available in the United States this season16. Vaccination providers can follow CDC guidance on routine vaccination during the COVID-19 pandemic and inform their patients about the processes they are using to provide safe vaccination services. Medical and public health professionals should continue to recommend influenza vaccination for unvaccinated persons and emphasize the value of receiving influenza vaccination at any point during the current influenza season, as long as there is potential for circulation of influenza viruses. CDC continues to assess influenza vaccination uptake during the 2020-21 season, with estimates updated frequently at the Weekly National Flu Vaccination Dashboard.

Authors

Megan C. Lindley, MPH; Anup Srivastav, PhD; Megan Hendrich, MA; Helen Fisun, MPH; Kimberly Nguyen, DrPH; Omar Pedraza, MPH; Hilda Razzaghi, PhD; James A. Singleton, PhD; Walter W. Williams, MD, MPH

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Content Source:
National Center for Immunization and Respiratory Diseases
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