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munized against mumps, reflecting the increasing vaccine use by private physicians. However, a February 1975 surVey of two-year old children indicated that only 56 per cent had received mumps vaccine compared to 84 per cent for measles vaccine. This appeared related to the Health Department's failure to provide mumps vaccine. By February 1976 the survey of two-year olds reflected the Health Department's mumps vaccine introduction with 79 per cent having had mumps vaccine versus 87 per cent for measles and rubella. The next survey of two-year old children is expected to indicate an almost identical percentage for all three vaccines, reflecting the Health Department's decision to use measles-mumps-rubella combination vaccine exclusively among children under age 13. Since mumps immunization is not yet required by law in the State of Washington, most school immunization status reports do not include this information. Based upon those schools where this has been reported, the survey data cited, and the mumps immunizations given by the Health Department, as of April 1977 it is estimated that no less than 60 per cent nor more than 75 per cent of the children in King County between the ages of 4 and 9 are immune to mumps. However, King County school immunization status reports in the fall of 1976 indicated that fewer than 5 per cent of elementary school children needed measles or rubella vaccines. This is also achievable for mumps.
Discussion The incidence of mumps and mumps encephalitis can be reduced 95 per cent by levels of mumps immunization which
appear to be significantly below those required for measles or rubella control. Serologic surveys are needed to determine what this level is. Immunization of 87 per cent of King County children against mumps by age two as is now the case with measles and rubella may be sufficient to completely eradicate this disease. Since mumps virus has no host other than man4 and measles-mumps-rubella combination vaccine is the basic vaccine used in King County by both the Health Department and private physicians, it should be possible to learn within the next two to three years whether this occurs. National policy should include provision of mumps immunization by all local health departments. Failure to do so will probably result in mumps epidemics among secondary school students and young adults as now seen with measles, because the natural virus is not sufficiently prevalent to expose many unimmunized children at younger ages. In the past, during both world wars, mumps was common among military recruits from rural areas.
REFERENCES 1. Center for Disease Control: Mumps Surveillance, January 1972June 1974. Issued October 1974. 2. Meyer, M. B. An epidemic study of mumps; Its spread in schools and families. Am. J. Hygiene, 75:259-281, 1962. 3. Levitt, L. P., Mahoney, D. H., Casey, H. L., and Bond, J. 0. Mumps in a general population. Am. J. Dis. Child. 120:134-8, August, 1970. 4. Henle, W. and Enders, J. F. Mumps Virus. In Viral and Rickettsial Infections of Man, Fourth Edition. Ed. by F. L. Horsfall and I. Tamm. Philadelphia: J. B. Lippincott Co., 1965. pp 755-68.
The Phantom Taxi Seat Belt CELESTE WELKON, BS, AND KEITH S. REISINGER, MD, MPH The use of seat belts has been demonstrated to reduce morbidity and mortality in automobile collisions. 1 2 Although seat belt usage in private automobiles has received some attention,3 there have been no reports on restraint utilization in public vehicles-taxi cabs. Taxi cabs are the only means of public transportation in more than 2,000 communities in the United States. People travel more miles in taxi cabs than in buses and urban trains combined.4 An impresFrom the Department of Community Medicine, University of Pittsburgh School of Medicine, and the Children's Hospital of Pittsburgh. Address reprint requests to Dr. Keith S. Reisinger, Children's Hospital of Pittsburgh, 125 DeSoto Street, Pittsburgh, PA 15213. This paper, submitted to the Journal April 15, 1977, was revised and accepted for publication May 9, 1977. AJPH November 1977, Vol. 67, No. 1 1
sion that taxi seat belts are often not present, or not in view-having fallen beneath the rear seat-prompted this study of the accessibility of seat belts in taxi cabs serving large eastern and midwestern metropolitan areas.
Methods Observations were made of the rear seat belts of taxi cabs awaiting passengers at four metropolitan airportsGreater Pittsburgh, O'Hare (Chicago), LaGuardia (New York), and Indianapolis. The evaluations were made by an observer standing outside the car or from the inside while interviewing the drivers concerning their attitudes on seat belt utilization. A seat belt was classified as "usable" if both 1091
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the male and female portions were in view. The study sample included taxi cabs from at least 25 companies in each of the cities except Pittsburgh, which has only one major company.
Results A total of 337 taxis were inspected at the four airports. The observations are summarized in Table 1. Although one portion (either male or female) of one or more seat belts was in view in 46.9 per cent of the taxi cabs, in only 14.5 per cent were there one or more usable belts. In Pittsburgh, New York, and Indianapolis, only 7 (3.4 per cent) of the 208 taxis inspected had at least one usable belt. The largest percentage with usable belts (32.6 per cent) was found in Chicago, where many of the taxi cabs had restraints constructed differently than those in other cities. In Pittsburgh, New York, and Indianapolis both seat belt sections were bolted to the chassis underneath the seat, whereas most Chicago taxi cabs had a shoulder-harness-type restraint with the shoulder section bolted above the seat and thus not likely to fall out of sight.
Comment More than 150 people die each year when the taxi cabs in which they are riding are involved in accidents. While the number of deaths to occupants of private motor vehicles declined 29 per cent between 1969 and 1974, the number of taxi cab passenger deaths remained stable.5 6 Although no data are available on the number of taxi cab passengers injured but not killed, an estimate based on the injury-to-fatality ratio in privately-owned cars would be 18,000.1- 7, 8 The actual, number may well be higher since taxi cab accidents tend to be urban, low-speed collisions.9 The data confirmed what many taxi passengers already know from their casual observations. Seat belts in the majority of cabs (85 per cent) are apparitional-one half there; the other half inextricably buried in the dust beneath the seat. TABLE 1-Taxi Rear Seat Belt Status by City Part of Belt Visible
Usable Seat Belt
72 77 59 129 337
36 31 14 77 158
50.0 40.3 23.7 59.7 46.9
2 3 2 42 49
New York Indianapolis
The use of seat belts reduces fatalities by approximately 50 per cent.'0 Since 25 per cent of drivers use seat belts in their private cars, it can be assumed that if belts were generally available in taxi cabs, some passengers would use them and a significant number of injuries and deaths would be prevented. Taxi cabs, like private cars, are required by federal regulations to have seat belts installed by the manufacturer prior to delivery. Many of the taxi cab drivers interviewed at the airports stated that not only do seat belts fall behind seats as a result of day-to-day use, but also some company mechanics purposely displace them during the taxi cabs' initial inspection after delivery. These companies place their passengers at an increased risk of injury or death as a result of their negligence in maintaining clean accessible seat belts. This disregard for the publics' safety might be changed if passengers injured in taxi cabs with inaccessible seat belts sued the taxi companies. Another possible way to change company practices is through legislation. Taxi cabs are a mode of public transportation and as such their operation is regulated by local and state government agencies. These regulations generally require that seat belts be present in the car, but do not stipulate that they be available for use. If taxi cab passengers are to have access to this basic safety measure, regulations requiring the companies to maintain clean available seat belts should be instituted.
REFERENCES I. Bohlin, N. J. A statistical analysis of 28,000 accident cases with emphasis on occupant restraint value. Eleventh Stapp Car Crash Conference, Society of Automotive Engineers, 1967. 2. Haddon, W. Jr. Reducing the damage of motor vehicle use. Technology Review 77:53-59, 1975. 3. Robertson, L. S. Belt use in 1975 cars: Initial data from one metropolitan area. Washington, DC: Insurance Institute for Highway Safety, 1975. 4. Fact Sheet on Taxicab Operations in the United States. Taxicab Management, International Taxicab Association. Feb. 1976. 5. Smith, S. D. Types of motor vehicle accidents 1969. Accident Facts: 56, 1976. 6. Smith, S. D. Types of motor vehicle accidents 1974. Accident Facts: 58, 1976. 7. Ryan, G. A. Injuries in traffic accidents. N. Engl. J. Med. 276: 1066-1076, 1967. 8. National Center for Health Statistics. Annual estimates of persons injured in motor vehicle accidents in the United States, 1968. Monthly Vital Statistics Report 19: July 1970. 9. Ryan, G. A. Injuries in urban and rural traffic accidents: a comparison of two studies. Eleventh Stapp Car Crash Conference, Society of Automotive Engineers, 1967. 10. Robertson, L. S. Estimates of motor vehicle seat belt effectiveness and use: Implications for occupant crash protection. Am J Public Health 66:859-864, 1976.
This study was supported in part by DHEW Grant 1-AO7AH 00317.
AJPH November 1977, Vol. 67, No. 11