PUBLIC HEALTH BRIEFS
women having immunity checks and those being tested prenatally. One of seven women re-tested after receiving rubella vaccine failed to seroconvert. Until mid-1975, it had been Health Department policy to refer all teenagers and older females to their family physicians for rubella antibody tests, birth control services, and immunization as necessary. Since that time, the policy has been modified to permit seronegative women to receive rubella vaccine through the Health Department after signing a specific informed consent statement including an affidavit relating to birth control. However, few seronegative women have sought rubella vaccine through the Health Department.
Discussion It is too early to determine the long-range impact of current U.S. rubella immunization policy because babies immunized in the early 1970s will not reach child-bearing age until the late 1980s. Thus far, however, results are encouraging based upon experience with that policy as implemented in Seattle-King County. Few cases of rubella are being reported and few, if any, pregnant women are being exposed to those which are reported. No local cases of congenital rubella syndrome have been observed since 1970, whereas 439 cases annually were uncovered in the previous six-year period. Antibody levels among women of child-bearing age during 1976 indicate that women under age 19 have the same degree of immunity as women age 20 and over. Most of the former have received rubella vaccine whereas most of the latter developed their immunity only as a result of natural infection. It is the cohort age 19 which has the greatest susceptibility to rubella. This is not unexpected, because that cohort was young enough (age 7-8) in 1964-1965 for many of its members to have missed being infected with natural rubella virus during and subsequent to that epidemic and too old (age 13) in 1970 to be included in the mass Seattle-King County elementary school rubella immunization program.
Failure of U.S. rubella immunization policy in SeattleKing County should begin to be observed soon, if a serious problem is likely to occur. Among the first signs would be a decline in the proportion of serologic specimens from teenagers which show rubella immunity. The pre-schoolers of 1970, most of whom have had no natural rubella exposure, will reach the age of serologic testing for rubella antibody by 1980. Another indicator is the number of reported rubella cases and the degree to which pregnant women are exposed to them as determined when epidemiologic follow-up of case reports is made. Finally, monitoring of all rubella serologies performed on newborns and young infants can indicate the occurrence of congenital rubella syndrome. These may be the first signs of an unrecognized problem in areas where rubella case reporting is poor.
Summary Assessment of the results of rubella hemagglutinationinhibition tests from women of child-bearing age in SeattleKing County suggests no community susceptibility problem except among women age 19 in 1976. Within this cohort 23 per cent were susceptible, probably because these women were too young to experience a full exposure to natural rubella prior to introduction of rubella vaccine and too old to be immunized against rubella in the elementary schools in 1970. Follow-up of women under age 25 who were seronegative for rubella antibody indicated that one-third subsequently received rubella vaccine.
REFERENCES 1. Peterson, D. R. and N. Chinn. Rubella-induced congenital defects and rubella immunization. Northwest Medicine 70:169-70, March, 1971. 2. Center for Disease Control: Rubella Surveillance, July, 1973-December, 1975. Issued August 1976. p. 10.
Mumps in Seattle-King County, Washington 1920-1976 MAX BADER, MD, MPH
Introduction Mumps is a rather benign childhood disease which usually involves the salivary glands and runs its course in 3-10 days. Mumps can also cause meningoencephalitis, orchitis, Address reprint requests to Dr. Max Bader, Epidemiologist, Seattle-King County Health Department, 2305 N.W. 94th St., Seattle, WA 98117. This paper, submitted to the Journal May 23, 1977, was accepted for publication July 8, 1977.
AJPH November 1977, Vol. 67, No. 11
oophoritis, pancreatitis, mastitis, arthritis, myocarditis, and cranial nerve damage. Death is rare. 1 2 The risk of a more severe course of mumps illness increases with age, but only about 15 per cent of children and 35 per cent of adults who get mumps suffer more than mild clinical symptoms. Live mumps vaccine was licensed in the United States in December 1967.* The Jeryl Lynn strain grown by Hille*Killed mumps vaccine was licensed a decade or two earlier. 1089
PUBLIC HEALTH BRIEFS
man in duck embryo tissue culture produces a non-communicable, sub-clinical infection that results in an antibody response in over 95 per cent of vaccine recipients.' Adverse reactions to the vaccine are rare and usually mild and of brief duration. Neutralizing antibody produced by the vaccine is initially lower in titer than that produced by natural infection, but it declines at a slower rate. Vaccine-induced neutralizing antibody and protection against clinical mumps are known to persist at least eight years after immunization. All available evidence suggests that mumps vaccine is at least as good as the other live virus vaccines. This is a brief report on the effect of mumps vaccine use in Seattle-King County, Washington (average population since 1970: 1,150,000).
Method Mumps has been a reportable disease in Seattle since 1909 and in all of King County since 1919. The only change in the reporting system since 1919 occurred in late 1976 when follow-up of reported cases was initiated because the number had declined to where this was possible. The numbers of cases reported each year to the Seattle-King County Health Department since 1920 were included in this study. Since historically over one-half the mumps reported both nationally and locally occurred in children ages 5-9, this population was used as a base for calculating an historical rate. All mumps cases regardless of age were used as the numerator. A straight line interpolation was made to obtain the 5-9 year old population between census years until 1970. The populations for the years 1971-1976 were obtained by using the 1970 census for each of the individual ages between 0-9 years plus birth information. Information on levels of immunization against mumps and ratio of children.immunized through public sources was obtained from Center for Disease Control data, surveys of Seattle area school children starting school for the first time in 1972 and 1973, and immunization surveys of representative samples of two-year-old King County children in 1975 and 1976. Information on number of cases of mumps encephalitis was obtained from Health Department and the Childrens' Orthopedic Hospital records.
sand children ages 5-9 is shown in Figure 1. At no time during the period 1920-1976 has this mumps case ratio been as low as for the years 1973-1976. The 156 cases of mumps in 1976 were the lowest ever recorded in King County. In addition, the 27 cases reported through April 1977 were 77 per cent below the 115 cases reported through April 1976. The median age of reported cases has increased from 6.5 years prior to live mumps vaccine introduction to 8.8 and 9.6 years respectively in 1975 and 1976. Between 1960 and 1967, an average of 17 cases of mumps encephalitis (range 7-30) were recorded annually in King County, a rate of 3.4 per thousand mumps reports compared with the national rate of 2.5. Since 1973, an average of three cases of mumps encephalitis (range 1-4) have been recorded annually in King County, a rate of 4.3 per thousand mumps reports. The Seattle-King County Health Department provides the immunizations for about 30 per cent of the children residing in King County. Prior to mid-1974, it administered mumps vaccine only to a few post-adolescent age males who had not had the disease. By the beginning of 1975, mumps vaccine in single or combination form was made available to all children seen by Health Department clinics, but was not included among immunizations offered at schools and preschools. Beginning in 1976, mumps vaccine was also provided to children at pre-schools and schools through grade 12 and through April 1977 they had received about 20,000 doses of vaccine. Survey data of children in King County reflect this history of vaccine introduction by the Health Department. In 1972, 30 per cent of Seattle area children starting school for the first time had been immunized (by private physicians) against mumps and only 3 per cent had had the disease, in contrast to past years here and elsewhere when the proportion who had had mumps on school entry was 20-25 per cent.3 By 1973, 40 per cent of school entrants had been im150
120
Results For a minor childhood disease, mumps has historically been well reported in Seattle-King County. Comparison of the number of cases during the years prior to introduction of live mumps vaccine with the child population of the area for the period 1920-1968 indicates reporting at about 30 per cent of the cases which actually should have occurred (proportion of persons during pre-vaccine period who eventually developed clinical mumps times the population at risk). Annually between 1968-1972, King County contributed 1.4-2.9 per cent of the nationally reported cases, even though it accounted for only 0.5 per cent of the U.S. population. The historical trend of the mumps case ratio per thou1 090
60
Year
FIGURE 1-Reported Mumps Cases 1920-1976, Seattle-King County, Washington Total Cases as a Ratio per 1,000 Children aged 5-9.
AJPH November 1977, Vol. 67, No. 11
PUBLIC HEALTH BRIEFS
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
women having immunity checks and those being tested prenatally. One of seven women re-tested after receiving rubella vaccine failed to seroconvert. Until mid-1975, it had been Health Department policy to refer all teenagers and older females to their family physicians for rubella antibody tests, birth control services, and immunization as necessary. Since that time, the policy has been modified to permit seronegative women to receive rubella vaccine through the Health Department after signing a specific informed consent statement including an affidavit relating to birth control. However, few seronegative women have sought rubella vaccine through the Health Department.
Discussion It is too early to determine the long-range impact of current U.S. rubella immunization policy because babies immunized in the early 1970s will not reach child-bearing age until the late 1980s. Thus far, however, results are encouraging based upon experience with that policy as implemented in Seattle-King County. Few cases of rubella are being reported and few, if any, pregnant women are being exposed to those which are reported. No local cases of congenital rubella syndrome have been observed since 1970, whereas 439 cases annually were uncovered in the previous six-year period. Antibody levels among women of child-bearing age during 1976 indicate that women under age 19 have the same degree of immunity as women age 20 and over. Most of the former have received rubella vaccine whereas most of the latter developed their immunity only as a result of natural infection. It is the cohort age 19 which has the greatest susceptibility to rubella. This is not unexpected, because that cohort was young enough (age 7-8) in 1964-1965 for many of its members to have missed being infected with natural rubella virus during and subsequent to that epidemic and too old (age 13) in 1970 to be included in the mass Seattle-King County elementary school rubella immunization program.
Failure of U.S. rubella immunization policy in SeattleKing County should begin to be observed soon, if a serious problem is likely to occur. Among the first signs would be a decline in the proportion of serologic specimens from teenagers which show rubella immunity. The pre-schoolers of 1970, most of whom have had no natural rubella exposure, will reach the age of serologic testing for rubella antibody by 1980. Another indicator is the number of reported rubella cases and the degree to which pregnant women are exposed to them as determined when epidemiologic follow-up of case reports is made. Finally, monitoring of all rubella serologies performed on newborns and young infants can indicate the occurrence of congenital rubella syndrome. These may be the first signs of an unrecognized problem in areas where rubella case reporting is poor.
Summary Assessment of the results of rubella hemagglutinationinhibition tests from women of child-bearing age in SeattleKing County suggests no community susceptibility problem except among women age 19 in 1976. Within this cohort 23 per cent were susceptible, probably because these women were too young to experience a full exposure to natural rubella prior to introduction of rubella vaccine and too old to be immunized against rubella in the elementary schools in 1970. Follow-up of women under age 25 who were seronegative for rubella antibody indicated that one-third subsequently received rubella vaccine.
REFERENCES 1. Peterson, D. R. and N. Chinn. Rubella-induced congenital defects and rubella immunization. Northwest Medicine 70:169-70, March, 1971. 2. Center for Disease Control: Rubella Surveillance, July, 1973-December, 1975. Issued August 1976. p. 10.
Mumps in Seattle-King County, Washington 1920-1976 MAX BADER, MD, MPH
Introduction Mumps is a rather benign childhood disease which usually involves the salivary glands and runs its course in 3-10 days. Mumps can also cause meningoencephalitis, orchitis, Address reprint requests to Dr. Max Bader, Epidemiologist, Seattle-King County Health Department, 2305 N.W. 94th St., Seattle, WA 98117. This paper, submitted to the Journal May 23, 1977, was accepted for publication July 8, 1977.
AJPH November 1977, Vol. 67, No. 11
oophoritis, pancreatitis, mastitis, arthritis, myocarditis, and cranial nerve damage. Death is rare. 1 2 The risk of a more severe course of mumps illness increases with age, but only about 15 per cent of children and 35 per cent of adults who get mumps suffer more than mild clinical symptoms. Live mumps vaccine was licensed in the United States in December 1967.* The Jeryl Lynn strain grown by Hille*Killed mumps vaccine was licensed a decade or two earlier. 1089
PUBLIC HEALTH BRIEFS
man in duck embryo tissue culture produces a non-communicable, sub-clinical infection that results in an antibody response in over 95 per cent of vaccine recipients.' Adverse reactions to the vaccine are rare and usually mild and of brief duration. Neutralizing antibody produced by the vaccine is initially lower in titer than that produced by natural infection, but it declines at a slower rate. Vaccine-induced neutralizing antibody and protection against clinical mumps are known to persist at least eight years after immunization. All available evidence suggests that mumps vaccine is at least as good as the other live virus vaccines. This is a brief report on the effect of mumps vaccine use in Seattle-King County, Washington (average population since 1970: 1,150,000).
Method Mumps has been a reportable disease in Seattle since 1909 and in all of King County since 1919. The only change in the reporting system since 1919 occurred in late 1976 when follow-up of reported cases was initiated because the number had declined to where this was possible. The numbers of cases reported each year to the Seattle-King County Health Department since 1920 were included in this study. Since historically over one-half the mumps reported both nationally and locally occurred in children ages 5-9, this population was used as a base for calculating an historical rate. All mumps cases regardless of age were used as the numerator. A straight line interpolation was made to obtain the 5-9 year old population between census years until 1970. The populations for the years 1971-1976 were obtained by using the 1970 census for each of the individual ages between 0-9 years plus birth information. Information on levels of immunization against mumps and ratio of children.immunized through public sources was obtained from Center for Disease Control data, surveys of Seattle area school children starting school for the first time in 1972 and 1973, and immunization surveys of representative samples of two-year-old King County children in 1975 and 1976. Information on number of cases of mumps encephalitis was obtained from Health Department and the Childrens' Orthopedic Hospital records.
sand children ages 5-9 is shown in Figure 1. At no time during the period 1920-1976 has this mumps case ratio been as low as for the years 1973-1976. The 156 cases of mumps in 1976 were the lowest ever recorded in King County. In addition, the 27 cases reported through April 1977 were 77 per cent below the 115 cases reported through April 1976. The median age of reported cases has increased from 6.5 years prior to live mumps vaccine introduction to 8.8 and 9.6 years respectively in 1975 and 1976. Between 1960 and 1967, an average of 17 cases of mumps encephalitis (range 7-30) were recorded annually in King County, a rate of 3.4 per thousand mumps reports compared with the national rate of 2.5. Since 1973, an average of three cases of mumps encephalitis (range 1-4) have been recorded annually in King County, a rate of 4.3 per thousand mumps reports. The Seattle-King County Health Department provides the immunizations for about 30 per cent of the children residing in King County. Prior to mid-1974, it administered mumps vaccine only to a few post-adolescent age males who had not had the disease. By the beginning of 1975, mumps vaccine in single or combination form was made available to all children seen by Health Department clinics, but was not included among immunizations offered at schools and preschools. Beginning in 1976, mumps vaccine was also provided to children at pre-schools and schools through grade 12 and through April 1977 they had received about 20,000 doses of vaccine. Survey data of children in King County reflect this history of vaccine introduction by the Health Department. In 1972, 30 per cent of Seattle area children starting school for the first time had been immunized (by private physicians) against mumps and only 3 per cent had had the disease, in contrast to past years here and elsewhere when the proportion who had had mumps on school entry was 20-25 per cent.3 By 1973, 40 per cent of school entrants had been im150
120
Results For a minor childhood disease, mumps has historically been well reported in Seattle-King County. Comparison of the number of cases during the years prior to introduction of live mumps vaccine with the child population of the area for the period 1920-1968 indicates reporting at about 30 per cent of the cases which actually should have occurred (proportion of persons during pre-vaccine period who eventually developed clinical mumps times the population at risk). Annually between 1968-1972, King County contributed 1.4-2.9 per cent of the nationally reported cases, even though it accounted for only 0.5 per cent of the U.S. population. The historical trend of the mumps case ratio per thou1 090
60
Year
FIGURE 1-Reported Mumps Cases 1920-1976, Seattle-King County, Washington Total Cases as a Ratio per 1,000 Children aged 5-9.
AJPH November 1977, Vol. 67, No. 11
PUBLIC HEALTH BRIEFS
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
