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Hospital admissions for pertussis in Spain, 1995–1998
Vaccine 19 (2001) 4791– 4794 www.elsevier.com/locate/vaccine
Hospital admissions for pertussis in Spain, 1995–1998 Angel Gil a,*, Itziar Oyagu¨ez a, Pilar Carrasco a, Antonio Gonza´lez b a
Department of Health Sciences, Rey Juan Carlos Uni6ersity, A6da de Atenas s/n, 28922 Alcorco´n, Madrid, Spain b Medical Department, A6entis Pasteur MSD, P o de la Castellana 141, 28046 Madrid, Spain Received 31 January 2001; received in revised form 28 May 2001; accepted 28 May 2001
Abstract This epidemiological survey was undertaken to estimate the annual burden of hospitalizations for pertussis in Spain during a four-year period 1995–1998. Data were obtained from the national surveillance system for hospital data. All hospital discharges for pertussis (ICD-9- CM 033) were analyzed. The annual incidence of hospitalization for pertussis was 1.7 per 100,000 population. Eighty-nine percent of the cases were B 1 year of age (incidence of 78 per 100,000) and 95% were 55 years of age (incidence of 28 per 100,000). During the study period, 14 deaths were reported among patients hospitalized by pertussis. Despite of the high inmunization rates, many pertussis cases occur each year, mostly of them among very young children. © 2001 Elsevier Science Ltd. All rights reserved. Keywords: Pertussis; Hospitalization; Spain
1. Introduction Immunization programs designed to protect young children against pertussis started in 1944 [1]. The incidence of pertussis has been greatly reduced by mass vaccination, but even in countries with high vaccination coverage, the disease is still present [2]. In Spain, universal vaccination against pertussis was introduced in 1965, reaching 94% coverage in 1997 [3]. Vaccination coverage for primary immunization with three doses of DTP in the first year of life is high and a booster dose at 15–18 months is recommended. A recently published cross sectional study had shown a prevalence of antibodies to Pertussis Toxin of 35% in the age group 5–12 years and of 52% in the age group 30 – 39 years, without a further increase thereafter [4]. These data suggest that there is widespread circulation of the organism in the population and that pertussis infection will likely to be frequent in adolescents and young adults [4]. Although hospitalization, complications and mortality in adolescents and adults are rare, they may serve as a reservoir for B. pertussis and play an important role in the * Corresponding author. Tel.: + 34-91-488-8804; fax: +34-91-4888848. E-mail address: [email protected] (A. Gil).
transmission to the very young infant [5,6]. To assess the incidence of pertussis is difficult, because a reliable etiologic diagnosis can only be established in a minority of cases [5]. Nonetheless, a reasonable approach to the burden of pertussis can be obtained from information on the hospitalizations, even though hospital admission will represent only the severe cases and vary substantially among different countries. This epidemiological survey was undertaken to estimate the annual burden of hospitalizations for pertussis in Spain during a fouryear period 1995 –1998.
2. Material and methods This study was based on the national surveillance system for hospital data (Conjunto Mı´nimo de Datos; CMBD) maintained by the Ministry of Health [7]. This system uses clinical codes for the Spanish version of the 9th International Classification of Diseases (Modificacio´n Clı´nica Clasificacio´n Internacional de Enfermedades; CIE-9-MC) and covers an estimated 83% of public hospitals [7,8]. Information on private hospitals is available only for a few autonomous regions, but these hospitals account for only a small proportion of all hospital admissions throughout Spain [7]. Compul-
0264-410X/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 2 6 4 - 4 1 0 X ( 0 1 ) 0 0 2 1 3 - 4
A. Gil et al. / Vaccine 19 (2001) 4791–4794
4792
sory health insurance covers an estimated 99.5% of the Spanish population, but persons not covered by health insurance can be treated in hospitals of the National Health System [9,10]. All hospital discharges for pertussis (ICD-9- CM 033; first listed diagnosis) were analyzed for the four-year study period (1 January 1995 through 31 December 1998). For each case of pertussis, data were gathered on age, sex, average length of stay, and outcome (survival to hospital discharge or died).
2.1. Statistical methods The average number of hospitalizations per year, annual incidence of hospital admissions (per 100,000 population), average length of stay in the hospital (ALOS), case-fatality ratio and the annual mortality rate (per 1,000,000 population) were calculated. Population figures obtained from the 1995– 1998 Spanish census projection, adjusted to the population covered by hospitals included in the CMBD surveillance system, were used for calculations. It was assumed that the distribution by age of the population covered by these public hospitals was equal to the general population [10]. Annual number of days of hospitalization were calculated by using the cumulative average number of cases per year and the ALOS. Statistical analyses were performed using SPSS software for personal computers (version 8.0; Chicago, IL).
3. Results A total of 2216 hospitalizations for pertussis was recorded during the study period 1995– 1998. Table 1 shows the average number of hospitalizations and incidence by group of age and by year. Eighty-nine percent of the cases were B1 year of age (incidence of 78 per 100,000 population) and 95% were 5 5 years of age (incidence of 28 per 100,000 population). Overall, the annual incidence was 1.7 per 100,000 population, with
the highest incidence reported in Andalucı´a and Extremadura (about three per 100,000 population) and the lowest in the Basque Country and La Rioja (about 0.6– 0.7 per 100,000 population). However, the highest annual incidence in persons 5 5 years in age was reported in Extremadura (about 48 per 100,000) and the lowest in the Canary Islands (about 10.7 per 100,000). The ALOS for all patients was of 9.1 (S.D., 7.3) days, 9.4 days for the B 1 year of age group; 6.0 days for 2– 10 years; 6.3 days for 10–50 years; and 8.7 days for \ 50 years. Overall, pertussis was responsible for almost 5109 days of hospitalizations per year; 5035 days in persons 5 10 years of age and 74 days in persons \ 10 years of age. During the 4 year study period, 14 deaths were reported among the patients hospitalized by pertussis, three in 1995, three in 1996, five in 1997 and three in 1998. Overall, the annual mortality rate of pertussis requiring hospitalization was 0.1 deaths per 1,000,000 population per year. Seventy-one percent of deaths occurred among children B 1 year of age and only two cases occurred in adults. However, the case-fatality ratio was higher in persons \ 50 years of age (28.6%) compared with those who were 1– 5 years (1.4%) and B 1 year in age (0.5%).
4. Discussion Pertussis is a national reportable disease in Spain since 1982 and 8686 cases were officially reported during the 1995–1998 period [11,12]. In this study a total of 2216 cases of hospitalization by pertussis were reported, that represents an estimated hospitalization rate of 25% of the reported cases. The overall annual incidence of hospitalization was about 1.7 per 100,000; but of 78 and 28 per 100,000 children B 1 year and 5 5 years in age, respectively. These results accord with studies in some other countries, the US, Canada and The Netherlands, showing that despite high immuniza-
Table 1 Average number of hospitalizations and incidence (per 100,000) by group of age and by year Age (years)
B1 1–2 3–5 6–10 11–20 21–30 31–50 \50 Total
1995
1996
1997
1998
Cases
Incidence
Cases
Incidence
Cases
Incidence
Cases
Incidence
378 13 20 5 5 0 1 1 423
60.2 4.1 2.1 0.3 0.1 0 0.01 0.01 1.3
515 15 21 24 4 0 1 1 581
80.8 4.9 2.2 1.4 0.1 0 0.01 0.01 1.8
809 18 37 29 16 0 4 4 917
127.9 5.6 3.8 1.7 0.4 0 0.04 0.04 2.8
269 8 7 5 3 2 0 1 295
42.6 2.5 0.7 0.3 0.1 0.01 0.02 0.02 0.9
A. Gil et al. / Vaccine 19 (2001) 4791–4794
tion rates, there are many pertussis cases each year [13 – 15]. According to our results, hospitalizations by pertussis in Spain increased in 1996 and 1997; but decreased in 1998 to an incidence lower than in 1995. This accords with data from the official case-reporting system, describing that pertussis in Spain follows 3 years epidemic cycles [11,12,16]. The incidence of hospitalization among children B 1 year of age was 14-fold higher than that among children 1–5 years of age and 46-fold higher than that among adolescents and adults. These results are in accordance with recently published data on the hospitalization for pertussis (ICD-9- CM 033) in The Netherlands, showing that the incidence of hospitalization in B 1 year of age during the 1989– 1995 period was approximately, 50 per 100,000 and more than 150 per 100,000 in 1996 and 1997 [15]. Our results also accord with a number of reports from the US, Australia and the UK showing an existing morbidity and mortality among very young children [13,17,18]. It has been described that young infants are most prone to complications and are most frequently hospitalized [19]. Since the diagnosis of pertussis is poor in children and is not expected to be better in adolescents and adults, only patients who presented with classic symptoms are likely to be diagnosed by clinicians and a fraction of them reported [20]. Thus, our case series is likely to reflects only the most severe part of the clinical spectrum. Given the underreporting of atypical pertussis cases, it is likely that the majority of pertussis cases in countries with high vaccination levels occur in adolescents and adults [13]. Transmission of B. pertussis from adults to children has been widely described, in fact, some epidemiological studies have demonstrated that 2 – 40% of primary cases are adults [21– 24]. A retrospective study in Denmark has reported that the source of infection in notified and hospitalized children B 1year-old was siblings in 59% of cases with available information on the source of infection [25]. Active immunization of infants will remain the cornerstone of the fight against pertussis. All efforts should thus primarily be directed to obtain a high coverage of primary vaccination in infants. However, current immunization programs have failed to eliminate the circulation of the organism. In the presence of continued high vaccination levels, substantial levels of morbidity in young children can be addressed by providing booster vaccination in older groups [26– 28]. The development of acellular vaccines, with improved tolerability profiles, provides an opportunity to implement booster vaccination in these groups. But, the decision to introduce a new vaccine intervention, such as pertussis vaccination of adolescents and adults, should be based on epidemiological and economic evidence to ensure that the new program is epidemiological justified and a cost-worthy investment. Cost benefit and cost effective-
4793
ness studies, estimating the health burden of pertussis in adults and adolescents plus the indirect effect on morbidity and mortality in very young infants, should thus be performed.
References [1] Cherry JD. Pertussis in the pre-antibiotic and pre-vaccine era, with emphasis on adult pertussis. Clin Infect Dis 1999;2(Suppl 28):S107 – 11. [2] Centers for Disease Control and Prevention. Resurgence of pertussis- United States, 1993. MMWR Morb Mortal Wkly Rep. 1993; 42: 952 – 960. [3] Instituto de Salud Carlos III. Ministerio de Sanidad y Consumo. Cobertura Vacunal 1997. Bol. Epidemiol. Sem. 1998; 6: 197 – 208. [4] Garcia-Corbeira P, Dal-Re R, Aguilar L, Garcia-de-Lomas J. Seroepidemiology of Bordetella pertussis infections in the Spanish population: a cross-sectional study. Vaccine 2000;18(21):2173 – 6. [5] Black S. Epidemiology of pertussis. Pediatr Infect Dis J 1997;16(Suppl 4):S85 – 9. [6] Guris D, Strebel PM, Bardenheier B, Brennan M, Tachdjian R, Finch E, et al. Changing epidemiology of pertussis in the United States: increasing reported incidence among adolescents and adults, 1990 – 1996. Clin Infect Dis 1999;28(6):1230 – 7. [7] Visser LE, Cano Portero R, Gay NJ, Martı´nez Navarro JF. Impact of rotavirus disease in Spain: an estimate of hospital admissions due to rotavirus. Acta Paediatr 1999;426 (Suppl):72 – 6. [8] Ministerio de Sanidad y Consumo. Clasificacio´ n Internacional de Enfermedades 9 Revisio´ n, Modificacio´ n Clı´nica (9th International Classification of Diseases, Clinical Modification). 1994. [9] Reverte-Cejudo D, Sa´ nchez-Bayle M. Devolving health services to Spain’s autonomous regions. Br Med J 1999;318:1204 –5. [10] F. Favereau and Associates, editors. Healthcare handbook, Vol. 4.2 Spain 1998 – 99. Lagon, France, 1998: 51 – 124. [11] Instituto de Salud Carlos III. Ministerio de Sanidad y Consumo. Enfermedades de Declaracio´ n Obligatoria en Espan˜ a. 1995 y 1996. Bol Epidemiol Sem 1997; 5: 2 – 7. [12] Instituto de Salud Carlos III. Ministerio de Sanidad y Consumo. Enfermedades de Declaracio´ n Obligatoria en Espan˜ a. Incidencia notificada en Espan˜ a. Bol Epidemiol Sem 1999; 7: 1 – 12. [13] Wortis N, Strebel PM, Wharton M, Bardenheir B, Hardy RB. Pertussis deaths: report of 23 cases in the United States, 1992 and 1993. Pediatrics 1996;97:607 – 12. [14] De Serres G, Shadmani R, Duval B, et al. Morbidity of pertussis in adolescents and adults. J Infect Dis 2000;182:174 – 9. [15] Melker HE de, Schellekens JFP, Neppelenbroek SE, Mooi FR, Rumke HC, Conyn-van Spaendonck MAE. Reemengence of pertussis in the highly vaccinated population of The Netherlands: observations on surveillance data. Emerg Infect Dis 2000;6:348 – 57. [16] Pizarro A, Pacho´ n I. Situacio´ n actual de te´ tanos y tos ferina. Bol Epidemiol Sem 1998;6:300 – 3. [17] Williams GD, Matthews NT, Choong RKC, Ferson MJ. Infant pertussis deaths in New South Wales 1996 – 1997. Med J Aust 1998;168:281 – 3. [18] Van Buynder PG, Owen D, Vurdien JE, Andrews NJ, Matthews RC, Miller E. Bordetella pertussis surveillance in England and Wales: 1995 – 1997. Epidemiol Infect 1999;123:403 – 11. [19] Heininger U, Stehr K, Cherry JD. Serious pertussis overlooked in infants. Eur J Pediatr 1992;151(5):342 – 3.
4794
A. Gil et al. / Vaccine 19 (2001) 4791–4794
[20] Deeks S, De Serres G, Boulianne N, et al. Failure of physicians to consider the diagnosis of pertussis in children. Clin Infect Dis 1999;28:840 – 6. [21] Storsaeter J, Blackwelder WC, Hallander HO. Pertussis antibodies, protection, and vaccine efficacy after household exposure. Am J Dis Child 1992;146(2):167 –72. [22] Mertsola J, Ruuskanen O, Eerola E, Viljanen MK. Intrafamilial spread of pertussis. J Pediatr 1983;103(3):359 – 63. [23] Baron S, Njamkepo E, Grimprel E, Begue P, Desenclos JC, Drucker J, et al. Epidemiology of pertussis in French hospitals in 1993 and 1994: thirty years after a routine use of vaccination. Pediatr Infect Dis J 1998;17(5):412 –8.
[24] Cherry JD. The role of Bordetella pertussis infections in adults in the epidemiology of pertussis. Dev Biol Stand 1997;89:181 –6. [25] Nielsen A, Larsen SO. Epidemiology of pertussis in Denmark: the impact of herd immunity. Int J Epidemiol 1994;23(6): 1300 – 8. [26] Mortimer EA. Pertussis and its prevention: a familiar affair. J Infect Dis 1990;161:473 – 9. [27] Novelli V, Al-Ansari H, Mok Q, Tasker R. Pertussis vaccination: is there a need for a booster dose? Lancet 1994;344: 1225 – 6. [28] Miller E, White JM, Fairley CK. Pertussis vaccination. Lancet 1994;344:1575 – 6.
Hospital admissions for pertussis in Spain, 1995–1998 Angel Gil a,*, Itziar Oyagu¨ez a, Pilar Carrasco a, Antonio Gonza´lez b a
Department of Health Sciences, Rey Juan Carlos Uni6ersity, A6da de Atenas s/n, 28922 Alcorco´n, Madrid, Spain b Medical Department, A6entis Pasteur MSD, P o de la Castellana 141, 28046 Madrid, Spain Received 31 January 2001; received in revised form 28 May 2001; accepted 28 May 2001
Abstract This epidemiological survey was undertaken to estimate the annual burden of hospitalizations for pertussis in Spain during a four-year period 1995–1998. Data were obtained from the national surveillance system for hospital data. All hospital discharges for pertussis (ICD-9- CM 033) were analyzed. The annual incidence of hospitalization for pertussis was 1.7 per 100,000 population. Eighty-nine percent of the cases were B 1 year of age (incidence of 78 per 100,000) and 95% were 55 years of age (incidence of 28 per 100,000). During the study period, 14 deaths were reported among patients hospitalized by pertussis. Despite of the high inmunization rates, many pertussis cases occur each year, mostly of them among very young children. © 2001 Elsevier Science Ltd. All rights reserved. Keywords: Pertussis; Hospitalization; Spain
1. Introduction Immunization programs designed to protect young children against pertussis started in 1944 [1]. The incidence of pertussis has been greatly reduced by mass vaccination, but even in countries with high vaccination coverage, the disease is still present [2]. In Spain, universal vaccination against pertussis was introduced in 1965, reaching 94% coverage in 1997 [3]. Vaccination coverage for primary immunization with three doses of DTP in the first year of life is high and a booster dose at 15–18 months is recommended. A recently published cross sectional study had shown a prevalence of antibodies to Pertussis Toxin of 35% in the age group 5–12 years and of 52% in the age group 30 – 39 years, without a further increase thereafter [4]. These data suggest that there is widespread circulation of the organism in the population and that pertussis infection will likely to be frequent in adolescents and young adults [4]. Although hospitalization, complications and mortality in adolescents and adults are rare, they may serve as a reservoir for B. pertussis and play an important role in the * Corresponding author. Tel.: + 34-91-488-8804; fax: +34-91-4888848. E-mail address: [email protected] (A. Gil).
transmission to the very young infant [5,6]. To assess the incidence of pertussis is difficult, because a reliable etiologic diagnosis can only be established in a minority of cases [5]. Nonetheless, a reasonable approach to the burden of pertussis can be obtained from information on the hospitalizations, even though hospital admission will represent only the severe cases and vary substantially among different countries. This epidemiological survey was undertaken to estimate the annual burden of hospitalizations for pertussis in Spain during a fouryear period 1995 –1998.
2. Material and methods This study was based on the national surveillance system for hospital data (Conjunto Mı´nimo de Datos; CMBD) maintained by the Ministry of Health [7]. This system uses clinical codes for the Spanish version of the 9th International Classification of Diseases (Modificacio´n Clı´nica Clasificacio´n Internacional de Enfermedades; CIE-9-MC) and covers an estimated 83% of public hospitals [7,8]. Information on private hospitals is available only for a few autonomous regions, but these hospitals account for only a small proportion of all hospital admissions throughout Spain [7]. Compul-
0264-410X/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 2 6 4 - 4 1 0 X ( 0 1 ) 0 0 2 1 3 - 4
A. Gil et al. / Vaccine 19 (2001) 4791–4794
4792
sory health insurance covers an estimated 99.5% of the Spanish population, but persons not covered by health insurance can be treated in hospitals of the National Health System [9,10]. All hospital discharges for pertussis (ICD-9- CM 033; first listed diagnosis) were analyzed for the four-year study period (1 January 1995 through 31 December 1998). For each case of pertussis, data were gathered on age, sex, average length of stay, and outcome (survival to hospital discharge or died).
2.1. Statistical methods The average number of hospitalizations per year, annual incidence of hospital admissions (per 100,000 population), average length of stay in the hospital (ALOS), case-fatality ratio and the annual mortality rate (per 1,000,000 population) were calculated. Population figures obtained from the 1995– 1998 Spanish census projection, adjusted to the population covered by hospitals included in the CMBD surveillance system, were used for calculations. It was assumed that the distribution by age of the population covered by these public hospitals was equal to the general population [10]. Annual number of days of hospitalization were calculated by using the cumulative average number of cases per year and the ALOS. Statistical analyses were performed using SPSS software for personal computers (version 8.0; Chicago, IL).
3. Results A total of 2216 hospitalizations for pertussis was recorded during the study period 1995– 1998. Table 1 shows the average number of hospitalizations and incidence by group of age and by year. Eighty-nine percent of the cases were B1 year of age (incidence of 78 per 100,000 population) and 95% were 5 5 years of age (incidence of 28 per 100,000 population). Overall, the annual incidence was 1.7 per 100,000 population, with
the highest incidence reported in Andalucı´a and Extremadura (about three per 100,000 population) and the lowest in the Basque Country and La Rioja (about 0.6– 0.7 per 100,000 population). However, the highest annual incidence in persons 5 5 years in age was reported in Extremadura (about 48 per 100,000) and the lowest in the Canary Islands (about 10.7 per 100,000). The ALOS for all patients was of 9.1 (S.D., 7.3) days, 9.4 days for the B 1 year of age group; 6.0 days for 2– 10 years; 6.3 days for 10–50 years; and 8.7 days for \ 50 years. Overall, pertussis was responsible for almost 5109 days of hospitalizations per year; 5035 days in persons 5 10 years of age and 74 days in persons \ 10 years of age. During the 4 year study period, 14 deaths were reported among the patients hospitalized by pertussis, three in 1995, three in 1996, five in 1997 and three in 1998. Overall, the annual mortality rate of pertussis requiring hospitalization was 0.1 deaths per 1,000,000 population per year. Seventy-one percent of deaths occurred among children B 1 year of age and only two cases occurred in adults. However, the case-fatality ratio was higher in persons \ 50 years of age (28.6%) compared with those who were 1– 5 years (1.4%) and B 1 year in age (0.5%).
4. Discussion Pertussis is a national reportable disease in Spain since 1982 and 8686 cases were officially reported during the 1995–1998 period [11,12]. In this study a total of 2216 cases of hospitalization by pertussis were reported, that represents an estimated hospitalization rate of 25% of the reported cases. The overall annual incidence of hospitalization was about 1.7 per 100,000; but of 78 and 28 per 100,000 children B 1 year and 5 5 years in age, respectively. These results accord with studies in some other countries, the US, Canada and The Netherlands, showing that despite high immuniza-
Table 1 Average number of hospitalizations and incidence (per 100,000) by group of age and by year Age (years)
B1 1–2 3–5 6–10 11–20 21–30 31–50 \50 Total
1995
1996
1997
1998
Cases
Incidence
Cases
Incidence
Cases
Incidence
Cases
Incidence
378 13 20 5 5 0 1 1 423
60.2 4.1 2.1 0.3 0.1 0 0.01 0.01 1.3
515 15 21 24 4 0 1 1 581
80.8 4.9 2.2 1.4 0.1 0 0.01 0.01 1.8
809 18 37 29 16 0 4 4 917
127.9 5.6 3.8 1.7 0.4 0 0.04 0.04 2.8
269 8 7 5 3 2 0 1 295
42.6 2.5 0.7 0.3 0.1 0.01 0.02 0.02 0.9
A. Gil et al. / Vaccine 19 (2001) 4791–4794
tion rates, there are many pertussis cases each year [13 – 15]. According to our results, hospitalizations by pertussis in Spain increased in 1996 and 1997; but decreased in 1998 to an incidence lower than in 1995. This accords with data from the official case-reporting system, describing that pertussis in Spain follows 3 years epidemic cycles [11,12,16]. The incidence of hospitalization among children B 1 year of age was 14-fold higher than that among children 1–5 years of age and 46-fold higher than that among adolescents and adults. These results are in accordance with recently published data on the hospitalization for pertussis (ICD-9- CM 033) in The Netherlands, showing that the incidence of hospitalization in B 1 year of age during the 1989– 1995 period was approximately, 50 per 100,000 and more than 150 per 100,000 in 1996 and 1997 [15]. Our results also accord with a number of reports from the US, Australia and the UK showing an existing morbidity and mortality among very young children [13,17,18]. It has been described that young infants are most prone to complications and are most frequently hospitalized [19]. Since the diagnosis of pertussis is poor in children and is not expected to be better in adolescents and adults, only patients who presented with classic symptoms are likely to be diagnosed by clinicians and a fraction of them reported [20]. Thus, our case series is likely to reflects only the most severe part of the clinical spectrum. Given the underreporting of atypical pertussis cases, it is likely that the majority of pertussis cases in countries with high vaccination levels occur in adolescents and adults [13]. Transmission of B. pertussis from adults to children has been widely described, in fact, some epidemiological studies have demonstrated that 2 – 40% of primary cases are adults [21– 24]. A retrospective study in Denmark has reported that the source of infection in notified and hospitalized children B 1year-old was siblings in 59% of cases with available information on the source of infection [25]. Active immunization of infants will remain the cornerstone of the fight against pertussis. All efforts should thus primarily be directed to obtain a high coverage of primary vaccination in infants. However, current immunization programs have failed to eliminate the circulation of the organism. In the presence of continued high vaccination levels, substantial levels of morbidity in young children can be addressed by providing booster vaccination in older groups [26– 28]. The development of acellular vaccines, with improved tolerability profiles, provides an opportunity to implement booster vaccination in these groups. But, the decision to introduce a new vaccine intervention, such as pertussis vaccination of adolescents and adults, should be based on epidemiological and economic evidence to ensure that the new program is epidemiological justified and a cost-worthy investment. Cost benefit and cost effective-
4793
ness studies, estimating the health burden of pertussis in adults and adolescents plus the indirect effect on morbidity and mortality in very young infants, should thus be performed.
References [1] Cherry JD. Pertussis in the pre-antibiotic and pre-vaccine era, with emphasis on adult pertussis. Clin Infect Dis 1999;2(Suppl 28):S107 – 11. [2] Centers for Disease Control and Prevention. Resurgence of pertussis- United States, 1993. MMWR Morb Mortal Wkly Rep. 1993; 42: 952 – 960. [3] Instituto de Salud Carlos III. Ministerio de Sanidad y Consumo. Cobertura Vacunal 1997. Bol. Epidemiol. Sem. 1998; 6: 197 – 208. [4] Garcia-Corbeira P, Dal-Re R, Aguilar L, Garcia-de-Lomas J. Seroepidemiology of Bordetella pertussis infections in the Spanish population: a cross-sectional study. Vaccine 2000;18(21):2173 – 6. [5] Black S. Epidemiology of pertussis. Pediatr Infect Dis J 1997;16(Suppl 4):S85 – 9. [6] Guris D, Strebel PM, Bardenheier B, Brennan M, Tachdjian R, Finch E, et al. Changing epidemiology of pertussis in the United States: increasing reported incidence among adolescents and adults, 1990 – 1996. Clin Infect Dis 1999;28(6):1230 – 7. [7] Visser LE, Cano Portero R, Gay NJ, Martı´nez Navarro JF. Impact of rotavirus disease in Spain: an estimate of hospital admissions due to rotavirus. Acta Paediatr 1999;426 (Suppl):72 – 6. [8] Ministerio de Sanidad y Consumo. Clasificacio´ n Internacional de Enfermedades 9 Revisio´ n, Modificacio´ n Clı´nica (9th International Classification of Diseases, Clinical Modification). 1994. [9] Reverte-Cejudo D, Sa´ nchez-Bayle M. Devolving health services to Spain’s autonomous regions. Br Med J 1999;318:1204 –5. [10] F. Favereau and Associates, editors. Healthcare handbook, Vol. 4.2 Spain 1998 – 99. Lagon, France, 1998: 51 – 124. [11] Instituto de Salud Carlos III. Ministerio de Sanidad y Consumo. Enfermedades de Declaracio´ n Obligatoria en Espan˜ a. 1995 y 1996. Bol Epidemiol Sem 1997; 5: 2 – 7. [12] Instituto de Salud Carlos III. Ministerio de Sanidad y Consumo. Enfermedades de Declaracio´ n Obligatoria en Espan˜ a. Incidencia notificada en Espan˜ a. Bol Epidemiol Sem 1999; 7: 1 – 12. [13] Wortis N, Strebel PM, Wharton M, Bardenheir B, Hardy RB. Pertussis deaths: report of 23 cases in the United States, 1992 and 1993. Pediatrics 1996;97:607 – 12. [14] De Serres G, Shadmani R, Duval B, et al. Morbidity of pertussis in adolescents and adults. J Infect Dis 2000;182:174 – 9. [15] Melker HE de, Schellekens JFP, Neppelenbroek SE, Mooi FR, Rumke HC, Conyn-van Spaendonck MAE. Reemengence of pertussis in the highly vaccinated population of The Netherlands: observations on surveillance data. Emerg Infect Dis 2000;6:348 – 57. [16] Pizarro A, Pacho´ n I. Situacio´ n actual de te´ tanos y tos ferina. Bol Epidemiol Sem 1998;6:300 – 3. [17] Williams GD, Matthews NT, Choong RKC, Ferson MJ. Infant pertussis deaths in New South Wales 1996 – 1997. Med J Aust 1998;168:281 – 3. [18] Van Buynder PG, Owen D, Vurdien JE, Andrews NJ, Matthews RC, Miller E. Bordetella pertussis surveillance in England and Wales: 1995 – 1997. Epidemiol Infect 1999;123:403 – 11. [19] Heininger U, Stehr K, Cherry JD. Serious pertussis overlooked in infants. Eur J Pediatr 1992;151(5):342 – 3.
4794
A. Gil et al. / Vaccine 19 (2001) 4791–4794
[20] Deeks S, De Serres G, Boulianne N, et al. Failure of physicians to consider the diagnosis of pertussis in children. Clin Infect Dis 1999;28:840 – 6. [21] Storsaeter J, Blackwelder WC, Hallander HO. Pertussis antibodies, protection, and vaccine efficacy after household exposure. Am J Dis Child 1992;146(2):167 –72. [22] Mertsola J, Ruuskanen O, Eerola E, Viljanen MK. Intrafamilial spread of pertussis. J Pediatr 1983;103(3):359 – 63. [23] Baron S, Njamkepo E, Grimprel E, Begue P, Desenclos JC, Drucker J, et al. Epidemiology of pertussis in French hospitals in 1993 and 1994: thirty years after a routine use of vaccination. Pediatr Infect Dis J 1998;17(5):412 –8.
[24] Cherry JD. The role of Bordetella pertussis infections in adults in the epidemiology of pertussis. Dev Biol Stand 1997;89:181 –6. [25] Nielsen A, Larsen SO. Epidemiology of pertussis in Denmark: the impact of herd immunity. Int J Epidemiol 1994;23(6): 1300 – 8. [26] Mortimer EA. Pertussis and its prevention: a familiar affair. J Infect Dis 1990;161:473 – 9. [27] Novelli V, Al-Ansari H, Mok Q, Tasker R. Pertussis vaccination: is there a need for a booster dose? Lancet 1994;344: 1225 – 6. [28] Miller E, White JM, Fairley CK. Pertussis vaccination. Lancet 1994;344:1575 – 6.