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Unlikely relevance for pandemic vaccine motivation

Posted by PLOS_CompBiol on 20 Feb 2008 at 20:00 GMT

Originally posted as a Reader Response on 9th May, 2007

The authors write that influenza epidemics can not be prevented by voluntary vaccination without incentives because "individuals [make] vaccination decisions each year on the basis of their past experiences. When epidemics occurred, some individuals became infected; this increased the probability that they would get vaccinated in the next influenza season."

They also state, without an explicit rationale: "Our results are applicable both for the control of seasonal and pandemic influenza."

The memory of having been infected, or not infected, during the previous interpandemic influenza season is unlikely to be a salient motivator after a pandemic begins.

The primary motivational aspects of memory and adaptability during a pandemic are likely to be the experience and knowledge of other people's morbidity and mortality - an availability heuristic far more vivid than a recent seasonal bout of the flu.

An additional aspect may be the increased demand generated by initially non-existent, and later inadequate, pandemic vaccine supply.

These and other hypotheses can probably be modeled if the stipulated attributes of memory and adaptability are revised to account for the conditions that are likely to apply during a pandemic.

Submitted by: Jody Lanard
E-mail: jody@psandman.com
Occupation: Psychiatrist and Risk Communication Consultant
The Peter Sandman Risk Communication Website

Reply to 'Unlikely relevance for pandemic vaccine motivation'

PLOS_CompBiol replied to PLOS_CompBiol on 21 Feb 2008 at 12:41 GMT

Originally posted as a Reader Response on 17th May, 2007

We thank Dr. Jody Lanard for her interest in our paper. Dr. Lanard raises two points:

A) ‘[Drs. Vardavas, Breban and Blower] also state, without an explicit rationale: "Our results are applicable both for the control of seasonal and pandemic influenza."’

The explicit rational is as follows. As mentioned in the paper (page 5) we ran our model with the added modification that on average an influenza pandemic occurs every 30 years. Under these conditions we found that the vaccination coverage dynamics and the response to the incentives were similar for both pandemic and inter-pandemic seasons.

B) ‘The memory of having been infected, or not infected, during the previous inter-pandemic influenza season is unlikely to be a salient motivator after a pandemic begins.’

We have modeled the vaccination behavior and the vaccination coverage level that would be expected at the beginning of the influenza season. At this point in time people would be unaware of whether an inter-pandemic or pandemic strain is likely to circulate and they would base their vaccination decisions on experience.

We note that we have modeled pre-season vaccination behavior. It would be possible to modify our model to include within season vaccination. This modification would allow individuals to respond to the perceived risk of infection during a pandemic.

We agree that other factors can be included in the model and this is the focus of current research.

Submitted by: Raffaele Vardavas
E-mail: vardavas@ucla.edu
Occupation: Dr./ Post-doc Researcher
UCLA