The gap in flu vaccination rates between elderly white, African-Americans, and Hispanics is amplified when vaccine supply is limited or delayed, according to a new study published in the American Journal of Preventative Medicine.
The study found that disparities in seasonal influenza vaccination rates between the groups grew by as much as 7% in years when there were problems with vaccine supply. By contrast, the gap narrowed by as much as 11% during years when the supply was more timely and abundant.
The researchers used data from the Medicare Current Beneficiary Survey, which consists of claims data and survey results of individual Medicare recipients, to look at seasonal influenza vaccination rates from 2000 to 2005. The data was broken into four “periods” consisting of two concurrent flu seasons during which the same group of individuals was followed for each period. For example, the same group of respondents was followed for the 2000-2001 and 2001-2002 vaccine seasons.
This method allowed researchers to compare individual activity during years in which vaccine supply fluctuated. The 2000-2001 and 2004-2005 seasons were characterized by severe vaccine shortages, 2001-2002 and 2003-2004 saw moderate shortages, and there were no supply problems during the 2002-2003 season.
Overall vaccinate rates among non-Hispanic whites ranged from 71% to 78% during the study period, significantly higher than rates among African-Americans (43% to 63%). Total vaccination rates were also lower among Hispanics which the study broke into English and Spanish speaking groups depending upon the language used to respond to the survey. Vaccination rates for English speaking Hispanics were 58% to 75%, while the rate for the Spanish speaking group was 31% to 53%, the lowest among the groups studied.
In the years when there were problems with vaccine supply, the gap in vaccination rates between whites and the other groups jumped by 2% to 7%, depending on the severity of the shortage. When flu seasons with supply problems were followed by seasons with adequate vaccine supply, the gap between the groups would narrow by 2% to 11%.
The study’s authors speculate that the sharper decline in vaccination rates among minorities is attributed to a number of factors including more pronounced vaccine shortages among providers in underserved communities and, in the case of Spanish-speaking populations, language barriers.
The authors recommend a more concerted effort to ensure clinics that serve vulnerable populations are prioritized for vaccine supply and that the government help mitigate the financial risk for these providers by covering the cost of purchasing the vaccines. They also recommend more broad-based and multilingual communication and outreach efforts.
Source: University of Rochester Medical Center