Seasonal influenza provides an excellent indicator of pandemic preparedness. If states can’t handle routine, seasonal flu, then they’re unlikely to be able to handle more severe, widespread outbreaks or bioterrorist attacks. In the United States, responsibility for preventing a health crisis falls largely on the shoulders of state and local officials. So are US states measuring up? Flu vaccination rates serve as a good proxy for answering that question.
The answer is, no—during the 2014-2015 flu season, a little under half of Americans were vaccinated, not enough to effectively curtail viral transmission. In contrast to their policies on vaccine-preventable childhood diseases such as measles, mumps, and polio, most states do not mandate flu vaccinations for children entering childcare or school. In other words, except for health care workers, who are strongly encouraged to get vaccinated, flu vaccines are voluntary, so state vaccination rates depend on ease of access and effectiveness of public health education efforts. Ideally, flu vaccination rates should exceed 60 percent in healthy populations. (This flu season, the vaccine produced was deemed only 60 percent effective, but that is still better than no coverage at all given how deadly the flu can be.) Vaccination rates varied from state to state, and understanding why may be the key to figuring out how states can better respond to such crises in the future.
In the United States, the Affordable Care Act (ACA) should have made flu vaccinations more accessible to the public since it mandates that health insurance companies cover flu and other vaccines without a co-payment. It’s been more than six years since President Barack Obama signed the ACA into law and almost four years since the Supreme Court upheld it. Intuitively, states that adopted the Medicaid expansion offered by the ACA should be expected to have higher flu vaccination rates by now than states that did not adopt it. However, that doesn’t seem to be the case.
The Centers for Disease Control and Prevention provides influenza vaccination rates by state. During the 2010-2011 flu season, which coincided with the ACA becoming law, the average national vaccination rate was 43 percent. It increased in each subsequent season, to 47.1 percent during 2014-2015.
The five states with the highest flu vaccination rates in 2014-2015 were South Dakota (59.6 percent), Rhode Island (58.7 percent), Massachusetts (54.9 percent), Nebraska (54 percent), and Iowa (53.8 percent). Of these top five, three—Massachusetts, Iowa, and Rhode Island—have adopted the ACA, while the other two have not. Unexpectedly, South Dakota had the highest flu vaccination rate in the country even though it has not adopted the ACA. On closer examination, though, this is not so surprising: US census data shows that South Dakota, while it did not adopt the ACA, has an uninsured rate of just 11.4 percent, which is lower than the national average of 12 percent.
The five states with the lowest vaccination rates were Florida (39.2 percent), Nevada (39.7 percent), Wyoming (40.4 percent), Arizona (41.6 percent), and Illinois (41.9 percent). Of these bottom five, three—Arizona, Nevada, and Illinois—have adopted the ACA and the other two have not.
These results suggest that flu vaccination rates are not completely dependent on health insurance access. If they were, then states with the highest uninsured rates would consistently have the lowest flu vaccination rates, but the reality is more complicated. Texas and Florida have the highest uninsured rates, 21.3 and 20.1 percent respectively. Not surprisingly, Florida has the lowest flu vaccination rate in the country, but Texas’ vaccination rate is a comparatively high 50.1 percent. Conversely, Massachusetts and Vermont have the lowest uninsured levels, at 3.8 and 5.9 percent respectively, but while Massachusetts has one of the highest flu vaccination rates at 54.9 percent, Vermont’s rate is slightly less than the Texas rate at 49.9 percent.
Clearly, something more influences flu vaccination rates than simply health insurance coverage. Each state is like a laboratory, testing which strategies work regarding public health education and preparedness. Unfortunately, aside from vaccination rates, it is hard to assess how successful states are in their efforts to mitigate the flu. State health departments report flu activity to the CDC each week based on estimated geographic spread, reporting on whether activity is absent, sporadic, local, regional, or widespread. But not everyone seeks healthcare when they have the flu, so these estimates cannot be exact. Cities report influenza deaths to the CDC, which tallies them at a national (but not state) level.
However, state-level influenza-associated pediatric death data is available. For the 2015-2016 flu season to date, there have been a total of 64 pediatric deaths nationwide. Back in the 2012-2013 influenza season, there were 171 pediatric flu-related deaths nationwide. The current flu season is still ongoing--in North America it can start as early as October and last into May--but if no additional pediatric deaths occur, then that would constitute a 63 percent decrease in pediatric flu-related deaths compared to the 2012-2013 season. Childhood flu vaccination coverage in 2012-2013 was 56.6 percent. The rate for 2015-2016 is not yet available, but if it is higher than what it was four years ago, that could be an indication that higher vaccination rates might have helped save young lives.
In short, adoption of the ACA seems to be an important, but not essential, criterion for achieving influenza preparedness. Some states, such as California, have strong anti-vaccination movements that could adversely influence rates. Since vaccination is one of the most effective strategies we have to prevent deaths from deadly epidemics and potential bioterrorist attacks, it behooves us to prepare for the unexpected by handling expected seasonal scourges such as influenza well. Ultimately, we need to have a better understanding of the factors that influence state influenza vaccination rates before the next public health catastrophe hits.