Navigation Links
Small increases in vaccine cost can cause large gaps in protection
Date:7/29/2010

CAMBRIDGE, Mass., July 29, 2010 -- Public immunization efforts may be much more sensitive than previously realized to small changes in the perceived costs or risks of vaccination, scientists at Harvard University report this week. In some cases, the spread of vaccine avoidance via social networks can make the difference between a minor, localized outbreak and an epidemic four times as large.

The finding, published in Proceedings of the Royal Society B, comes amidst one of the worst pertussis outbreaks in 50 years, in which 1,500 Californians have contracted whooping cough. Public health officials have cited reduced vigilance in vaccinating against the disease, which sickens 90 percent of those exposed to it.

"People sometimes say that voluntary vaccination is doomed to fail because of the 'free-rider' problem, in which people assume they will be protected by other people's immunity," says co-author Daniel I. Rosenbloom, a graduate student in Harvard's Program for Evolutionary Dynamics, led by Martin A. Nowak. "We find that's not true, as a population of self-interested people can defeat an epidemic. But the trouble is, success is sensitive to small changes in perception of a vaccine's costs -- in terms of money, time, inconvenience, or perceived side effects."

Together with lead author Feng Fu, Rosenbloom and Nowak are the first researchers to incorporate epidemiological data into modeling of how vaccination spreads by imitation in a social network. They found that increasing vaccination cost prompts more free-riding and leads to larger epidemics.

"Herd immunity in a social network is fragile," says Fu, a postdoctoral researcher in mathematical biology at Harvard. "As public perceptions of vaccine side effects change, a population can rapidly switch from high vaccination and herd immunity to low vaccination and a larger epidemic."

The good news, the authors say, is that the sensitivity of vaccination to perceived costs cuts both ways, meaning it's easy to get a population back on track with voluntary immunizations in the wake of an outbreak.

The Harvard team found epidemics are amplified when individuals mimic others in their social network, such as by avoiding immunizations during vaccine scares. Behavior driven by "strong imitation" -- reliance on anecdotal information from social contacts in deciding whether or not to immunize -- could cause up to a 14 percent decline in vaccination rates, and a four-fold increase in the size of a flulike epidemic.

"It's possible to be too clever for your own good in dealing with risk," Fu says. "These 'strong imitators' chase unwise risks, and their behavior exacerbates the fragility of herd immunity, causing it to break down more easily. Those in our model who ignored friends' outcomes and stuck with their own decision ended up better off, on average."

Fu, Rosenbloom, and Nowak's modeling also showed that in an epidemic, individuals who are hubs in a social network are likelier to choose vaccination than their less connected peers. However, this outcome emerges primarily from self-interested behavior -- the desire to avoid sickness -- rather than altruistic behavior to protect friends and family.

"Altruistic behavior could certainly lead to increased vaccination of hubs, but we find that it's not required -- self-interested behavior suffices," Rosenbloom says.

This work builds upon the tradition of evolutionary game theory, where researchers construct simple mathematical models to explore human behavior in social dilemmas and scenarios where people can cooperate for the common good. While this study specifically modeled influenza, the results apply to a wide variety of diseases, and are consistent with data from past epidemics.


'/>"/>

Contact: Steve Bradt
steve_bradt@harvard.edu
617-496-8070
Harvard University
Source:Eurekalert

Related medicine news :

1. Smaller hospitals can provide safe and high-quality surgical care comparable to larger counterparts
2. Small investment could save 11 million African lives
3. Sam's Club Tests Online Small Business Loan Program for Main Street
4. Sex With Recent Smallpox Vaccine Recipient Can Lead to Illness
5. Triad Web Design Ranked #23 on the Top 100 Small Businesses List by Business Leader Magazine
6. X-ISS Launches Free Online Disaster Recovery Planning Assessment Tools for Small Businesses
7. Small Supplement And Vitamin Manufacturers Must Meet FDA cGMP Requirements By The End Of The Month
8. Organic Clothing – Is Your Clothing Delivering Death in Small Doses?
9. A prognostic and predictive biomarker for nonsmall cell lung cancer
10. Dog Sniffs Out Prostate Cancer in Small Study
11. Comparision of overall survival for non-small cell lung cancer patients
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/25/2016)... ... June 25, 2016 , ... "With 30 hand-drawn hand gesture ... said Christina Austin - CEO of Pixel Film Studios. , ProHand Cartoon’s package ... Final Cut Pro X . Simply select a ProHand generator and drag it ...
(Date:6/25/2016)... (PRWEB) , ... June 25, 2016 , ... On Friday, ... presented a Bronze Wellness at Work award to iHire in recognition of their exemplary ... part of the 7th annual Maryland Workplace Health & Wellness Symposium at the BWI ...
(Date:6/24/2016)... ... ... June 19, 2016 is World Sickle Cell Observance Day. In an effort ... holistic treatments, Serenity Recovery Center of Marne, Michigan, has issued a pain ... Disease (SCD) is a disorder of the red blood cells, which can cause episodes ...
(Date:6/24/2016)... ... June 24, 2016 , ... Dr. ... accelerated orthodontic treatment. Dr. Cheng has extensive experience with all areas of orthodontics, ... and accelerated osteogenic orthodontics. , Micro-osteoperforation is a revolutionary adjunct to orthodontic ...
(Date:6/24/2016)... ... June 24, 2016 , ... EB Medicine presented its first-ever ... Medicine conference in Ponte Vedra Beach, FL. The awards honor the outstanding work ... Practice and Pediatric Emergency Medicine Practice. , “With this award, we recognize ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... NAMUR , Belgium , ...  (NYSE MKT: VNRX), today announced the appointment of ... Board of Directors as a Non-Executive Director, effective ... the Company,s Audit, Compensation and Nominations and Governance ... Board, Dr. Futcher will provide independent expertise and ...
(Date:6/23/2016)... Research and Markets has announced ... Type (Organic Chemical (Sugar, Petrochemical, Glycerin), Inorganic Chemical), Functionality ... - Global Forecast to 2021" report to their ... global pharmaceutical excipients market is projected to reach USD ... in the forecast period 2016 to 2021. ...
(Date:6/23/2016)... 2016 Research and Markets has announced ... report to their offering. ... a favourable commercial environment for MedImmune to enter. The US ... will serve to drive considerable growth for effective anti-influenza medications. ... cap sales considerably, but development is still in its infancy. ...
Breaking Medicine Technology: