National Bureau of Economic Research

Abstract: Does a one percent increase in aggregate driving increase accident costs by more than one percent? Vickrey [1968] and Edlin [1999] answer yes, arguing that as a new driver takes to the road, she increases the accident risk to others as well as assuming risk herself. On the other hand, more driving could result in increased congestion, lower speeds, and less severe or less frequent accidents. We study the question with panel data on state-average insurance premiums and loss costs. We …nd that in high tra¢c density states, an increase in tra¢c density dramatically increases aggregate insurance premiums and loss costs. In California, for example, we estimate that a typical additional driver increases the total of other people’s insurance costs by $1271-2432. In contrast, the accident externality per driver in low tra¢c states appears quite small. On balance, accident externalities are so large that a correcting Pigouvian tax could raise$45 billion in California alone, and over $140 billion nationally. It is not clear the extent to which this externality results from increases in accident rates, accident severity or both. It is also not clear whether the same externality pertains to underinsured accident costs like fatality risk

Injection Drug Use Is a Risk Factor for HCV Infection in Urban Egypt

OBJECTIVE: To identify current risk factors for hepatitis C virus (HCV) transmission in Greater Cairo. DESIGN AND SETTING: A 1:1 matched case-control study was conducted comparing incident acute symptomatic hepatitis C patients in two "fever" hospitals of Greater Cairo with two control groups: household members of the cases and acute hepatitis A patients diagnosed at the same hospitals. Controls were matched on the same age and sex to cases and were all anti-HCV antibody negative. Iatrogenic, community and household exposures to HCV in the one to six months before symptoms onset for cases, and date of interview for controls, were exhaustively assessed. RESULTS: From 2002 to 2007, 94 definite acute symptomatic HCV cases and 188 controls were enrolled in the study. In multivariate analysis, intravenous injections (OR = 5.0; 95% CI = 1.2-20.2), medical stitches (OR = 4.2; 95% CI = 1.6-11.3), injection drug use (IDU) (OR = 7.9; 95% CI = 1.4-43.5), recent marriage (OR = 3.3; 95% CI = 1.1-9.9) and illiteracy (OR = 3.9; 95% CI = 1.8-8.5) were independently associated with an increased HCV risk. CONCLUSION: In urban Cairo, invasive health care procedures remain a source of HCV transmission and IDU is an emerging risk factor. Strict application of standard precautions during health care is a priority. Implementation of comprehensive infection prevention programs for IDU should be considered