But it's not ideal, and the very act of watching the pandemic can distort the findings--like trying to measure both the location and the energy of a subatomic particle. Excerpt:
A potential disadvantage of using syndromic surveillance systems is the lack of specificity of the data collected. Laboratory reporting of confirmed cases provides an accurate representation of how many cases are positive for the pathogen of interest.
Syndromic surveillance monitors disease patterns using syndromic indicators, which are primarily based upon clinically diagnosed (but not confirmed) episodes or symptom presentation. However, previous work has shown that despite these limitations, syndromic data can be extremely sensitive to community-based infections and act as potential early warning of imminent problems.
This ‘broad brush’ approach of using non-specific indicators may capture patients who do not specifically meet the case definition, e.g. ILI. Experience from using the NHS Direct/HPA syndromic surveillance system has demonstrated that calls for ‘fever’ in children aged between five and 14 years can be used as an early warning indicator of influenza activity .
Fever calls in this age group are sensitive to increasing community-based influenza activity, thus demonstrating that using an indicator that is not based upon a range of presenting symptoms associated with influenza can be reliably used to monitor influenza activity .
Another potential disadvantage of syndromic surveillance is the impact of media reporting. In situations such as the outbreak of severe acute respiratory syndrome (SARS) in 2003, and the current H1N1 influenza pandemic, the mass media reporting on these events can cause anxiety amongst the population. This can prompt symptomatic patients, who would normally have self-treated their symptoms, to seek healthcare advice such as a GP consultation or a call to NHS Direct.
It is therefore very difficult to disentangle the effects of media reporting from the true burden of infection in the community, and without laboratory reporting it is not possible to estimate the proportion of true positives.