A recent study from UCLA researchers suggests that widespread Covid-19 vaccination advertising has an effect on other public health behaviors that has not been previously recognized. According to the authors, the fall in adult flu vaccination rates in states with low Covid-19 vaccination rates may be a sign of waning public confidence in public health. This suggests that Covid-19 vaccination behavior has spread to flu vaccination behavior. The discovery is detailed in a letter to the editor that is published in The New England Journal of Medicine.
There are several factors that have contributed to lower rates of COVID-19 vaccination and have also spilled over to affect flu vaccination rates. These factors include:
- Misinformation and vaccine hesitancy: There has been a lot of misinformation about COVID-19 vaccines, which has contributed to vaccine hesitancy. This hesitancy has also extended to flu vaccines, as some people may be hesitant to get any vaccine.
- Limited access to vaccines: The COVID-19 pandemic has caused disruptions in the supply chain for vaccines, leading to limited access in some areas. This has also affected the availability of flu vaccines.
- Prioritization of COVID-19 vaccines: In the early stages of the pandemic, the priority was to get COVID-19 vaccines to as many people as possible. This may have led to a decrease in the number of flu vaccines that were distributed.
- Changes in vaccination behaviors: The COVID-19 pandemic has led to changes in how vaccines are distributed and administered, which may have affected vaccination behaviors. For example, some people may be hesitant to visit a healthcare facility to get a vaccine due to concerns about COVID-19 transmission.
Overall, a combination of these factors has contributed to lower rates of COVID-19 and flu vaccination.
“It is alarming that controversy surrounding Covid-19 vaccination may be undermining separate public health efforts that save thousands of lives each year,” says the study’s lead author Richard Leuchter, MD, a resident physician at UCLA Health and the David Geffen School of Medicine.
“Many Americans who never before declined a routine, potentially life-saving vaccine have started to do so. This supports what I have seen in my clinical practice and suggests that information and policies specific to Covid-19 vaccines may be eroding more general faith in medicine and our government’s role in public health.”
The authors used publicly available data from the Centers for Disease Control and Prevention (CDC) collected through January 2022 to evaluate how flu vaccination rates changed during the pandemic based on state-wide rates of Covid-19 vaccination.
Much as someone’s decision to wear or forgo a mask in public during the early pandemic was linked with their more general beliefs through the idea of ‘belief signaling’, we propose that ‘belief generalization’ may account for Covid-19 vaccine-specific opinions being generalized to other vaccines. People who feel compelled to oppose or support Covid-19 vaccines may feel that they should in turn oppose or support other vaccines.
Richard Leuchter
Flu vaccination rates for the initial pandemic season (2020–2021), which came before Covid-19 vaccinations were widely accessible, remained largely consistent across all states. However, in areas with below-average rates of Covid-19 vaccination, flu vaccination rates fell 4.5 percentage points (from 43.7% to 39.2%) during the second flu season of the pandemic (2021–2022), which was after considerable advertising of the vaccine. On the other hand, the average flu vaccination rate increased by 3.8 percentage points (from 49.0% to 52.8%) in the states with the highest uptake of Covid-19 vaccinations.
According to the authors, these results collectively imply that Covid-19 vaccination practices have spread to other public health behaviors, in this case flu vaccine practices. They explain that this relationship works in both directions: factors causing low Covid-19 vaccination rates (e.g., mistrust of Covid-19 vaccines, concerns about side effects, lack of trust in government) are linked to declines in flu vaccination compared to pre-pandemic times, whereas factors causing high rates of Covid-19 vaccination are spilling over to increase flu vaccination rates.
The authors propose that both of these trends may be explained by something called belief generalization.
“Much as someone’s decision to wear or forgo a mask in public during the early pandemic was linked with their more general beliefs through the idea of ‘belief signaling’, we propose that ‘belief generalization’ may account for Covid-19 vaccine-specific opinions being generalized to other vaccines,” says Leuchter. “People who feel compelled to oppose or support Covid-19 vaccines may feel that they should in turn oppose or support other vaccines.”
Rates of full vaccination against Covid-19 (i.e., both doses of a two-dose vaccine or one dose of a single-dose vaccine) varied from 50% (Alabama) to 81% (Rhode Island) through January 2022. Flu vaccination rates through January of the 2021-2022 flu season were also highly variable, ranging from 31% (Mississippi) to 59% (Connecticut).
According to the study’s authors, the average Covid-19 immunization rate in a state alone can account for 60% of the difference in that state’s flu vaccination rate.
“This is compelling evidence that the vaccination behaviors for flu and Covid-19 vaccines are inextricably linked,” said Leuchter.
The authors note that these findings apply only to the general adult population. Flu vaccination rates among children fell uniformly and precipitously across both the 2020-2021 and 2021-2022 flu seasons, regardless of when Covid-19 vaccines were introduced or state-wide rates of Covid-19 vaccination.
The authors note that earlier research has revealed comparable severe nationwide drops in childhood measles, mumps, and rubella (MMR) vaccination rates. According to Leuchter, belief generalization from Covid-19 vaccines may partially explain why parents are choosing not to vaccinate their children routinely, but the fact that childhood flu vaccination rates decreased even in states with high rates of Covid-19 vaccination suggests that this trend is not entirely attributable to belief generalization from Covid-19 vaccines.
Reassuringly, flu vaccination rates among adults over 65 years of age remained relatively stable during these two flu seasons compared to the 2019-2020 season, albeit persistently underutilized in this population.
This study had some limitations. For instance, it did not assess people’s opinions or motivations for skipping vaccinations. As an observational study, it cannot demonstrate that the recent decrease in flu vaccination rates was brought on by a lack of confidence in vaccinations or in the government. Additionally, as county-level statistics for the 2021–2022 flu season were not made available by the CDC and flu vaccination rates are reported based on self-report surveys, only state-level data were used.
Despite these drawbacks, the researchers contend that these results should serve as a wake-up call and spur thorough investigation into the reasons behind declines in non-Covid-19 immunization rates in order to guide urgent action and corrective policies.
This research was supported by the NIH-National Heart, Lung, and Blood Institute Stimulating Access to Research in Residency (StARR) program at UCLA, the NIH-National Institute on Aging, the National Center for Advancing Translational Science (NCATS) UCLA Clinical and Translational Science Institute (CTSI), and the UCLA Value-Based Care Research Consortium (VBCRC).
Co-authors of the study are Drs. Nick Jackson, John Mafi, and Catherine Sarkisian, all faculty members in the UCLA Department of Medicine, Division of General Internal Medicine and Health Services Research.
