- Email: [email protected]
Thiomersal removal: effects on the safety and immunogenicity of the chiron influenza vaccines AGRIPPAL® and FLUAD®
International Congress Series 1263 (2004) 457 – 460
www.ics-elsevier.com
Thiomersal removal: effects on the safety and immunogenicity of the chiron influenza vaccines AGRIPPALR and FLUADR Daniela Toneatto a,*, Roberto Bugarini a, Barbara Corbellini a, Michael Penlington a, Domenico Vaccina b, Ada Minutello a a
Chiron Vaccines, Clinical Research and Medical Affairs, Via Fiorentina, 1, 53100 Siena, SI, Italy b Azienda USL, Modena, Italy
Abstract. Thiomersal is an organic mercurial compound that has been used for over 60 years as an antimicrobial agent to prevent bacterial and fungal contamination. Due to public concern about the possible toxicity of thiomersal, several regulatory agencies, including the European Agency for Evaluation of Medicinal Products and the Food Drug Administration, issued statements calling for removal of thiomersal from vaccines. Two randomized studies were performed to evaluate the effects, if any, of the complete removal of thiomersal on the safety and immunogenicity of FLUADR and AGRIPPALR influenza vaccines. D 2004 Published by Elsevier B.V. Keywords: Thiomersal; Vaccine; Influenza
1. Introduction Influenza is still a major health concern in the world. The elderly and those with underlying chronic disease are at increased risk of complications from influenza infection. The significant increase in mortality during an influenza epidemic is a direct result not only of pneumonia but also of cardiopulmonary or other chronic diseases that can be exacerbated by influenza infection. Several studies have provided evidence that flu vaccination is effectively reducing the risk of death and morbidity both in healthy individuals and in people with underlying chronic diseases. The Chiron inactivated subunit influenza vaccines, AGRIPPALR (Agrippal) and FLUADR (Fluad: an adjuvanted vaccine), are suspensions containing purified surface antigens of influenza virus types A and B, propagated in embryonated chicken eggs, then inactivated and purified. Analyses of a database of about 13,000 subjects indicate a consistent higher immunogenicity of Fluad when compared with nonadjuvanted vaccines in the elderly and to a lesser extent, nonelderly adults. * Corresponding author. Tel.: +39-577243364; fax: +39-577243551. E-mail address: [email protected] (D. Toneatto). 0531-5131/ D 2004 Published by Elsevier B.V. doi:10.1016/j.ics.2004.02.070
458
D. Toneatto et al. / International Congress Series 1263 (2004) 457–460
Fluad and Agrippal, like most inactivated vaccines and all influenza vaccines, contained thiomersal as a preservative. At doses much higher than those used in vaccines, the preservative has been reported to cause neurotoxicity and nephrotoxicity [1]. However, the precise nature of exposure to thiomersal from vaccines remains uncertain. On October 20, 1999, the Advisory Committee on Immunization Practices (ACIP) reviewed information about thiomersal in vaccines and received updates from CDC’s National Immunization Program and several vaccine manufacturers on the current and anticipated availability of vaccines that do not contain thiomersal as a preservative. Because of its excellent track record of safety and efficacy as a vaccine preservative over many years, WHO continues to recommend vaccines containing thiomersal, particularly for multidose presentations [2]. On balance, the known risk of morbidity and mortality from vaccine-preventable diseases far outweigh any potential risk posed by thiomersal. Nonetheless, the European Agency for the Evaluation of Medicinal Products (EMEA) [3] has stated that thiomersal must be removed from all single dose presentation vaccines. Chiron vaccines removed thiomersal as a preservative; however, traces of this compound were still present in the marketed vaccine formulation. The purpose of this study is to evaluate the effects, if any, of the complete removal of thiomersal from the manufacturing process on the safety and immunogenicity of Fluad and Agrippal vaccines. 2. Methods 2.1. Study design The two trials (phase II, randomized, observer blind, controlled, parallel group, single center) were designed to evaluate the safety and immunogenicity of Agrippal and Fluad after the complete removal of traces of thiomersal. The controls were the registered vaccines (i.e., with traces of thiomersal). A single IM injection of vaccine was administered preferably in the deltoid muscle of the nondominant arm. Subjects were observed for immediate reactions for 30 min after vaccination (Day 0); axillary temperature was noted in addition to any other symptoms at 6 h postvaccination. Subjects were instructed to complete a diary card for 3 days after vaccination to describe local reactions (e.g., pain, erythema, ecchymosis, swelling and induration) and systemic reactions [e.g., fever (i.e., axillary temperature z38 jC), chills, malaise, headache, myalgia, arthralgia, sweating, fatigue] and were contacted by phone at Day 4 to obtain local and systemic reaction data and to assess the subjects’ clinical status. All adverse events, including any serious adverse event, any adverse event necessitating a physician’s visit and any adverse event resulting in a subject’s withdrawal from the study, were collected throughout the trial. Immunogenicity of the study vaccines were evaluated based on SRH assay of blood samples drawn at study Visit 1 (Day 0) and Visit 2 (Day 21). Blood samples were obtained prior to (Day 0), and 21 days after vaccination. On each of the scheduled days, venous blood was drawn from all subjects. Antibody responses to the three antigens contained in the vaccine (A/H3N2, A/H1N1, and B) were assayed by SRH.
D. Toneatto et al. / International Congress Series 1263 (2004) 457–460
459
2.2. Statistical methods To assess the immunogenicity objective, the noninferiority testing approach compared the postvaccination geometric mean areas (GMAs) of both vaccine groups in each population for each of the three vaccine antigens. The noninferiority assumption was to be rejected if the postvaccination GMA ratio of the control to test vaccine was z2. Postvaccination (Day 21) GMAs and associated 90% CIs were computed by exponentiating (base 10) the least-squares mean values of the logarithmically transformed (base 10) areas and their 90% CIs obtained from Analysis of Variance (ANOVA) with a factor for vaccine group. 3. Results 3.1. Subject disposition, demography and other baseline characteristics Of the 299 subjects enrolled into the first study, 150 were vaccinated with thiomersalfree Fluad (Fluad test) and 149 with Fluad containing trace amounts of thiomersal (Fluad control). In the second study, 295 subjects were enrolled of whom 147 were vaccinated with thiomersal-free Agrippal (Agrippal test) and 146 with Agrippal containing trace amounts of thiomersal (Agrippal control). Within each study, the demographic and other baseline characteristics were similar between the groups. 3.2. Immunogenicity The baseline antibody levels against each of the three vaccine strains were similar between the groups. The immune response to each of the three vaccine antigens, as measured by GMA, was also similar regardless of whether the vaccine contained thiomersal. The ratios of postvaccination GMAs for the Fluad control to those of the Fluad test were 0.84, 0.95 and 1.07 for the A/H3N2, A/H1N1 and B strains, respectively (Table 1). For the Agrippal study the ratios of GMAs for the control to test group were 1.01, 1.07 and 1.15 for the A/H3N2, A/H1N1 and B strains, also respectively (Table 1). For both studies and all antigens, the upper confidence limits of the 90% confidence intervals of these ratios were also less than 2. Table 1 Postvaccination GMA ratios Fluad study
A/Moscow/10/99like (H3N2) A/New Caledonia/20/99like (H1N1) B/Hong Kong/330/ 2001-like
Agrippal study
Day 21 control: thiomersal-free GMA ratio
90% confidence intervals
Day 21 control: thiomersal-free GMA ratio
90% confidence intervals
0.84
0.67 – 1.05
1.07
0.86 – 1.34
0.95
0.77 – 1.18
1.15
0.93 – 1.41
1.07
0.86 – 1.34
1.17
0.92 – 1.49
460
D. Toneatto et al. / International Congress Series 1263 (2004) 457–460
3.3. Safety In both study populations, the local reactions were generally mild, transient, and within the range expected. The proportion of subjects from test groups experiencing each local reaction was generally similar to the respective controls. The local reaction most commonly experienced by both study populations was pain at the injection site (20% Fluad test group, 15% of the Fluad control group, 5% of both Agrippal vaccination groups). Other local reactions were reported infrequently (overall range: 1– 5% all groups). Most systemic reactions were also mild and transient. The proportion of subjects experiencing each systemic reaction was broadly similar and within the expected range. Headache was the most common systemic reaction among recipients of the thiomersal-free Fluad group (9%); malaise was the second most common (7%). The most common systemic reactions among the Fluad control were equally malaise, myalgia, arthralgia, and headache, (5% for each). No death or serious adverse event, or adverse event leading to the withdrawal of a subject occurred. All reactions were within the ranges stipulated in current product literature. In each group, the incidences of adverse reactions ranged between 1% and 4%. 4. Conclusions The aim of this study was to assess the possible effect on immunogenicity and safety of the removal of the traces of thiomersal from the previously licensed FLUADR and AGRIPPALR vaccines, as requested by WHO [2] and EMEA [3]. In this study, we found that the postvaccination GMAs of the thiomersal-free vaccination group were not inferior to those of the control group for any of the strains. The range of frequencies, severities, and durations of each local and each systemic reaction was lower than that expected from previous clinical trial data. The occurrences of at least possibly related other adverse events were similar between the vaccination groups and generally consisted of common complaints experienced by the elderly. These results enable us to conclude that the removal of the trace thiomersal did not affect adversely neither immunogenicity nor safety of Fluad and Agrippal. References [1] R. Pfab, et al., Clinical course of severe poisoning with thiomersal, Clin. Toxicol. 34 (1996) 453 – 460. [2] WHO, Thiomersal as a vaccine preservative, Wkly. Epidemiol. Rec. 2 (2000) 12 – 16. [3] EMEA, Points to consider on the reduction, elimination or substitution of thiomersal in vaccines, CPMP/ BWP/2517/00.
www.ics-elsevier.com
Thiomersal removal: effects on the safety and immunogenicity of the chiron influenza vaccines AGRIPPALR and FLUADR Daniela Toneatto a,*, Roberto Bugarini a, Barbara Corbellini a, Michael Penlington a, Domenico Vaccina b, Ada Minutello a a
Chiron Vaccines, Clinical Research and Medical Affairs, Via Fiorentina, 1, 53100 Siena, SI, Italy b Azienda USL, Modena, Italy
Abstract. Thiomersal is an organic mercurial compound that has been used for over 60 years as an antimicrobial agent to prevent bacterial and fungal contamination. Due to public concern about the possible toxicity of thiomersal, several regulatory agencies, including the European Agency for Evaluation of Medicinal Products and the Food Drug Administration, issued statements calling for removal of thiomersal from vaccines. Two randomized studies were performed to evaluate the effects, if any, of the complete removal of thiomersal on the safety and immunogenicity of FLUADR and AGRIPPALR influenza vaccines. D 2004 Published by Elsevier B.V. Keywords: Thiomersal; Vaccine; Influenza
1. Introduction Influenza is still a major health concern in the world. The elderly and those with underlying chronic disease are at increased risk of complications from influenza infection. The significant increase in mortality during an influenza epidemic is a direct result not only of pneumonia but also of cardiopulmonary or other chronic diseases that can be exacerbated by influenza infection. Several studies have provided evidence that flu vaccination is effectively reducing the risk of death and morbidity both in healthy individuals and in people with underlying chronic diseases. The Chiron inactivated subunit influenza vaccines, AGRIPPALR (Agrippal) and FLUADR (Fluad: an adjuvanted vaccine), are suspensions containing purified surface antigens of influenza virus types A and B, propagated in embryonated chicken eggs, then inactivated and purified. Analyses of a database of about 13,000 subjects indicate a consistent higher immunogenicity of Fluad when compared with nonadjuvanted vaccines in the elderly and to a lesser extent, nonelderly adults. * Corresponding author. Tel.: +39-577243364; fax: +39-577243551. E-mail address: [email protected] (D. Toneatto). 0531-5131/ D 2004 Published by Elsevier B.V. doi:10.1016/j.ics.2004.02.070
458
D. Toneatto et al. / International Congress Series 1263 (2004) 457–460
Fluad and Agrippal, like most inactivated vaccines and all influenza vaccines, contained thiomersal as a preservative. At doses much higher than those used in vaccines, the preservative has been reported to cause neurotoxicity and nephrotoxicity [1]. However, the precise nature of exposure to thiomersal from vaccines remains uncertain. On October 20, 1999, the Advisory Committee on Immunization Practices (ACIP) reviewed information about thiomersal in vaccines and received updates from CDC’s National Immunization Program and several vaccine manufacturers on the current and anticipated availability of vaccines that do not contain thiomersal as a preservative. Because of its excellent track record of safety and efficacy as a vaccine preservative over many years, WHO continues to recommend vaccines containing thiomersal, particularly for multidose presentations [2]. On balance, the known risk of morbidity and mortality from vaccine-preventable diseases far outweigh any potential risk posed by thiomersal. Nonetheless, the European Agency for the Evaluation of Medicinal Products (EMEA) [3] has stated that thiomersal must be removed from all single dose presentation vaccines. Chiron vaccines removed thiomersal as a preservative; however, traces of this compound were still present in the marketed vaccine formulation. The purpose of this study is to evaluate the effects, if any, of the complete removal of thiomersal from the manufacturing process on the safety and immunogenicity of Fluad and Agrippal vaccines. 2. Methods 2.1. Study design The two trials (phase II, randomized, observer blind, controlled, parallel group, single center) were designed to evaluate the safety and immunogenicity of Agrippal and Fluad after the complete removal of traces of thiomersal. The controls were the registered vaccines (i.e., with traces of thiomersal). A single IM injection of vaccine was administered preferably in the deltoid muscle of the nondominant arm. Subjects were observed for immediate reactions for 30 min after vaccination (Day 0); axillary temperature was noted in addition to any other symptoms at 6 h postvaccination. Subjects were instructed to complete a diary card for 3 days after vaccination to describe local reactions (e.g., pain, erythema, ecchymosis, swelling and induration) and systemic reactions [e.g., fever (i.e., axillary temperature z38 jC), chills, malaise, headache, myalgia, arthralgia, sweating, fatigue] and were contacted by phone at Day 4 to obtain local and systemic reaction data and to assess the subjects’ clinical status. All adverse events, including any serious adverse event, any adverse event necessitating a physician’s visit and any adverse event resulting in a subject’s withdrawal from the study, were collected throughout the trial. Immunogenicity of the study vaccines were evaluated based on SRH assay of blood samples drawn at study Visit 1 (Day 0) and Visit 2 (Day 21). Blood samples were obtained prior to (Day 0), and 21 days after vaccination. On each of the scheduled days, venous blood was drawn from all subjects. Antibody responses to the three antigens contained in the vaccine (A/H3N2, A/H1N1, and B) were assayed by SRH.
D. Toneatto et al. / International Congress Series 1263 (2004) 457–460
459
2.2. Statistical methods To assess the immunogenicity objective, the noninferiority testing approach compared the postvaccination geometric mean areas (GMAs) of both vaccine groups in each population for each of the three vaccine antigens. The noninferiority assumption was to be rejected if the postvaccination GMA ratio of the control to test vaccine was z2. Postvaccination (Day 21) GMAs and associated 90% CIs were computed by exponentiating (base 10) the least-squares mean values of the logarithmically transformed (base 10) areas and their 90% CIs obtained from Analysis of Variance (ANOVA) with a factor for vaccine group. 3. Results 3.1. Subject disposition, demography and other baseline characteristics Of the 299 subjects enrolled into the first study, 150 were vaccinated with thiomersalfree Fluad (Fluad test) and 149 with Fluad containing trace amounts of thiomersal (Fluad control). In the second study, 295 subjects were enrolled of whom 147 were vaccinated with thiomersal-free Agrippal (Agrippal test) and 146 with Agrippal containing trace amounts of thiomersal (Agrippal control). Within each study, the demographic and other baseline characteristics were similar between the groups. 3.2. Immunogenicity The baseline antibody levels against each of the three vaccine strains were similar between the groups. The immune response to each of the three vaccine antigens, as measured by GMA, was also similar regardless of whether the vaccine contained thiomersal. The ratios of postvaccination GMAs for the Fluad control to those of the Fluad test were 0.84, 0.95 and 1.07 for the A/H3N2, A/H1N1 and B strains, respectively (Table 1). For the Agrippal study the ratios of GMAs for the control to test group were 1.01, 1.07 and 1.15 for the A/H3N2, A/H1N1 and B strains, also respectively (Table 1). For both studies and all antigens, the upper confidence limits of the 90% confidence intervals of these ratios were also less than 2. Table 1 Postvaccination GMA ratios Fluad study
A/Moscow/10/99like (H3N2) A/New Caledonia/20/99like (H1N1) B/Hong Kong/330/ 2001-like
Agrippal study
Day 21 control: thiomersal-free GMA ratio
90% confidence intervals
Day 21 control: thiomersal-free GMA ratio
90% confidence intervals
0.84
0.67 – 1.05
1.07
0.86 – 1.34
0.95
0.77 – 1.18
1.15
0.93 – 1.41
1.07
0.86 – 1.34
1.17
0.92 – 1.49
460
D. Toneatto et al. / International Congress Series 1263 (2004) 457–460
3.3. Safety In both study populations, the local reactions were generally mild, transient, and within the range expected. The proportion of subjects from test groups experiencing each local reaction was generally similar to the respective controls. The local reaction most commonly experienced by both study populations was pain at the injection site (20% Fluad test group, 15% of the Fluad control group, 5% of both Agrippal vaccination groups). Other local reactions were reported infrequently (overall range: 1– 5% all groups). Most systemic reactions were also mild and transient. The proportion of subjects experiencing each systemic reaction was broadly similar and within the expected range. Headache was the most common systemic reaction among recipients of the thiomersal-free Fluad group (9%); malaise was the second most common (7%). The most common systemic reactions among the Fluad control were equally malaise, myalgia, arthralgia, and headache, (5% for each). No death or serious adverse event, or adverse event leading to the withdrawal of a subject occurred. All reactions were within the ranges stipulated in current product literature. In each group, the incidences of adverse reactions ranged between 1% and 4%. 4. Conclusions The aim of this study was to assess the possible effect on immunogenicity and safety of the removal of the traces of thiomersal from the previously licensed FLUADR and AGRIPPALR vaccines, as requested by WHO [2] and EMEA [3]. In this study, we found that the postvaccination GMAs of the thiomersal-free vaccination group were not inferior to those of the control group for any of the strains. The range of frequencies, severities, and durations of each local and each systemic reaction was lower than that expected from previous clinical trial data. The occurrences of at least possibly related other adverse events were similar between the vaccination groups and generally consisted of common complaints experienced by the elderly. These results enable us to conclude that the removal of the trace thiomersal did not affect adversely neither immunogenicity nor safety of Fluad and Agrippal. References [1] R. Pfab, et al., Clinical course of severe poisoning with thiomersal, Clin. Toxicol. 34 (1996) 453 – 460. [2] WHO, Thiomersal as a vaccine preservative, Wkly. Epidemiol. Rec. 2 (2000) 12 – 16. [3] EMEA, Points to consider on the reduction, elimination or substitution of thiomersal in vaccines, CPMP/ BWP/2517/00.