In our previous post, we described the social influence of a credible forecast of vaccine drift had on a local community. Notably, nearly 40% of those families who vaccinated their children opted to specifically vaccinate for the 2012-2013 influenza season as the result of hearing the forecast. It was noted that the recommended influenza vaccine composition was updated to account for virus drift, and it was this vaccine that was recommended to our patients as the follow-on to advisement of the forecast.
According to CDC, the national hospitalization rates for children 0-4 yrs old during the 2011-2012 and 2012-2013 seasons were 15.8 and 65.6 per 100,000, respectively:
During the 2011-2012 season, we observed no hospitalizations for influenza in this age group. During the 2012-2013 season, we observed 9 admissions, all of whom were within this age group. We observed no admissions in the 5-17 year old age group. There were no fatalities in either season.
Six of the nine admissions were children seen in our clinic and for whom we had vaccination history, as well as whether they received instruction regarding the forecast. In all six cases neither did they receive the forecast, nor did they opt to vaccinate for the 2012-2013 influenza season.
We note that hospitalization rates for influenza in our county are typically below national average, regardless of what season we examine. We believe this is due to a variety of factors due as our county not representative of a major traffic hub and is relatively isolated from the rest of our state. Further, we observe high compliance rates of breast feeding and vaccination in general, both of which contribute to herd immunity. That said, compliance for seasonal influenza vaccination in prior seasons has not been optimal as noted in the prior post.
We observe several features comparing the two seasons in our county:
1. Seasonal influenza vaccination compliance for the 2012-2013 was influenced heavily by a credible forecast of vaccine drift and hence, expected higher rates of morbidity and mortality.
2. Hospitalization rates were higher during the 2012-2013 season.
3. While higher during the 2012-2013 season, our hospitalization rates were 2% of the national average.
3. We observed that every one of our patients hospitalized neither heard the forecast nor were vaccinated.
We conclude that this simplistic case study provides supportive evidence that credible, dynamically validated forecasts of influenza vaccine drift played a role in promoting community resilience and mitigation of patient surge at our hospital.
Obviously, a far larger study encompassing many years and far larger sample size of patients is required to achieve stastistically meaningful conclusions. But this little exercise might compel the funding of just such a study someday...