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Experiences from vaccination and revaccination of teenage girls with three different rubella vaccines
Journal
of Biological
Stadurdization
1976 4, 107-114
Experiences from vaccination and revaccination of teenagegirls with three different rubella vaccines* M. Btittigerf
and L. Hellert
The following results were obtained from the vaccination of 3000 schoolgirls between 13 and 14 years of age, with three different rubella vaccines, Ahnevax, Cendevax and Meruvax. Seventy-two per cent of the girls stating a negative rubella anamnesis were found negative in an HI-test against rubella, whereas 33% of the girls claiming to have suffered from rubella were negative. Initially only girls with a negative anamnesis were vaccinated. The antibody conversion rates when calculated only from the initially seronegative girls 8 weeks after vaccination were 97.6% for Almevax, 96.1 o/0 for Cendevax and 91.5?; for Meruvax. The postvaccination geometric mean titre of the Almevax group of primary seronegative girls was 1 : 185 and the corresponding titres of the Cendevax and Meruvax groups were 1 : 82 and 1 : 73. The mean titre of naturally immune girls was 1 : 380 before vaccination. Recognizable reactions of arthritis occurred in less than 1% of the vaccinees. The investigation of the first vaccination trial indicated that all the three vaccines tested gave satisfactory conversion rates in girls seronegative to rubella before vaccination. Sidereactions were negligible. Immunization with Almevax resulted in higher mean titre levels 8 weeks after vaccination than the other two vaccines tested. A follow-up study carried out 1 year later indicated that a number of the girls with low or no demonstrable titres ( d 1 : 16) 8 weeks after the first vaccination had acquired titres 1 : 32 or above during the following year. During the same period the previously unvaccinated group of primari ly seronegative girls showed significantly lower conversion rates. This difference could thus not be explained by the occurrence of natural rubella infections only. Lastly, in contrast to prevaccination seronegative and primovaccinated girls the revaccinated so-called ‘vaccine failures’ generally reacted with a rapid anamnestic response upon restimulation with the virus antigen. These findings indicate that the immune response to the primary vaccination might have been better than shown by the early determined conversion rates.
INTRODUCTION This study was initiated in close cooperation with the Swedish national board of health and welfare in order to obtain the data and experiences necessary to evaluate the immediate and long-term effects of active immunization of schoolgirls against rubella. * Received for publication 19 November 1975. t The National Bacteriological Laboratory, S-105 21 Stockholm,
Sweden.
107
NI. BiiTTIGER MATERIAL
AND AND
L. HELLER METHODS
Three parentally administered rubella vaccines were used, namely Almevax (Burroughs Wellcome), Cendevax (Smith Kline & French) and Meruvax (Merck Sharp & Dohme). They are cultivated on human diploid cells, rabbit kidney cells and duck embryo cells, respectively. The dose injected was the one recommended by the manufacturer. Hemagglutination-inhibition antibody (HIA) titres were determined after treatment of sera with heparin and manganous chloride and by use of erythrocytes of newborn chickens. One ampoule of the international standard serum was suspended in 5 ml of buffer and titrated in parallel. This suspension held a titre of 1 : 32 to 1 : 64. The Jirst vaccination
round
In the autumn of 1972 questionnaires concerning participation in rubella vaccination in Stockholm were distributed to 4000 schoolgirls in the sixth and seventh grade (13-14 years old) and their parents. Three thousand of them declared that they were willing to take part in the study. Half of the girls (Table 1) stated that they probably had had rubella and the other half believed that they had not yet had the disease. TABLE
Girls
with
1. Prevalence of HI-antibodies (titres < 1 : 8) in girls stating positive and negative rubella anamnesis
negative
rubella anamnesis Girls with positiwe rubella
Number of sera tested
Seronegative (HI-titre less than 1 :8)
1324
957
2
365
72.3
1423
471
7
945
33.1
2747
1428
9
1310
52.0
Equivocal (HI-titre =1:8)
Seropositive (HI-titre 1 :16or higher)
Percentage seronegatives
anamnesis
Total population
tested
Initially all the girls were bled for antibody investigations, but only the half with the negative rubella anamnesis was vaccinated during the winter of 1972-73. The vaccinated Questionnaires requesting information half was bled again 8 weeks after the vaccination. on fever, rash, throat disorders and pains in joints or swelling of joints during the postvaccination period were distributed to all vaccinees and also to a number of unvaccinated schoolmates at the time of the vaccination. They were collected after about 6 weeks. The second vaccination
round
The following winter (1973-74) a number of the vaccinees who had not responded to the vaccination, i.e. those with titres less than 1 : 8 or with low titres (1 : 8 or 1 : 16 only) Five of these had been 8 weeks after the immunization, were contacted for revaccination. primary vaccinated with Almevax, 39 with Cendevax and 40 with Meruvax. A number of the girls, who had stated a positive rubella anamnesis but who had been found negative or displaying low antibody titres the year before, were also offered vaccination. All reThe revaccinated girls were bled for vaccinations were performed with Almevax. antibody investigation prior to, 10 days and 8 weeks after vaccination. A number of girls primovaccinated with Almevax were tested likewise. 108
VACCINATION
AND
REVACCINATION
RESULTS The first vaccinations The results of the initial serum investigations are given in Table 1. Seventy-two per cent of the girls with a negative rubella anamnesis lacked demonstrable antibodies (titre < 1 : 8). The corresponding figure of the half claiming to have been infected with rubella was 330/b. The conversion rates from titres < 1 : 8 to titres > 1 : 16 are illustrated in Fig. 1. In all groups the conversion rate 8 weeks after vaccination was above 90%, the girls vaccinated with Almevax showing the highest figure, 97*60,/,.
I
AI~VOX 284/291
100 -
ii!
c&-
Cendevo 299/31
98%
c
Meruvax
1
27W
96%
92%
1 :
Fig. 1. Conversion
rates of prevaccination seronegative girls (proportion titres ( > 1 : 16) 8 weeks after vaccination).
of girls with HI-
The geometric mean titres were 1 : 182, 1 : 82 and 1 : 73 for the Almevax, Cendevax and Meruvax vaccinated girls, respectively (all seronegative prior to vaccination). The titre distributions illustrating also median titres are illustrated in Fig. 2. It can also be seen in Fig. 2 that the girls naturally immune prior to the vaccination had higher titre 100 90 80 70 60Median antibody titres y-J--------------------
40 30 20 IO 4
8
16
32
64
HI-antibody
128
256
512
1024 2048
litre
Fig. 2. Immunologic profiles (accumulated titre distributions) 8 weeks after vaccination of the different groups of vaccinees seronegative prior to vaccination with Almevax (-.--.-) Cendevax (-...-..*-) and Meruvax ( *o*..*) and of naturally immune girls prior to vaccination (-).
109
M.
BOTTIGER
AND
I,. tiEI,I,ISR
levels than those shown by the prevaccination seronegative vaccinees 8 weeks after t& immunization. The booster effect on girls naturally immune prior to the immunization was slightly more marked in girls given Almevax and Meruvax compared with the Cendevax group (Table 2). Variations between different batches were also evaluated (Fig. 3). No statistical differences were found between the pairs of batches used for vaccination with each vaccine.
TABLE 2. Effect of booster in girls with HI-titres
2 1 : 16
Proportion of girls showing fourfold antibody rise after vaccination*
Vaccine
23/123 22/123 7/104
Almevax Meruvax Cendevax
(18.7%) (17.9%) ( 6.7%)
* The difference between Cendevax and the other two vaccines was significant at the
P
r AkWVOX
Cendevax
Meruvox 15/154 -
IO -
5-
51152
7/170 -
Lot I
Lot 2
Lot I
Lot 2 _
Fig. 3. Comparison between batches. Proportions of rubella susceptible girls (prevaccination seronegative) seroconverting 8 weeks after vaccination with different batches of the three vaccines tested.
Side-reactions Reported postvaccination reactions are listed in Table 3. Unfortunately it was not possible to include a placebo group for these evaluations. It can be seen, however, that there were no significant differences concerning fever, rash, throat and joint complaints between girls seronegative or seropositive prior to vaccination. Unvaccinated schoolmates had complaints of the same magnitude during the same period. Only joint complaints differed between vaccinated and unvaccinated. Twenty of the vaccinees stated that they had felt some swelling of the joints (Table 4). School nurses had been especially requested to report immediately about such symptoms. Three cases were reported and inspected by a physician during the actual postvaccination period. Two of them had the migrating but soon disappearing swellings described as typical (Swartz, Klingberg, Goldwasser, Klingberg, Goldblom & Hilleman, 1971) to appear after rubella vaccination. One girl contracted arthritis following a diagnosed streptococcal infection of the throat. 110
VACCINATION
AND
REVACCINATION
TABLE 3. Percentage of girls reporting different symptoms during the 6-week period following vaccination Vaccinated girls
Complaint
r Cendevax (%I
Fever Rash Throat symptoms Joint symptoms
17 10 32 17
Seroconverting A Almevax (%I
yeir;vax 0 0
,
Preimmune (all vaccines) (%I
12 9 31 15
20 7 28 13
16 11 33 16
TABLE 4. Prevalence of complaints
reporting
Prevaccination seronegative Prevaccination immune Seronegative
after vaccination
18 4 29 5
swelling of joints after vaccination
Total Type of vaccine
Unvaccinated girls (%I
Swollen joints ,-*-,
Vaccine
No.
No.
01’ 10
Almevax
284 299 278 350 46
4 5 6 3 1
1.4 1.7 2.2 0.9 2.2
Cendevax Meruvax All vaccines 9,
(Cultures from her knee-joint were negative for rubella, as well as her antibody titres to rubella 2 and 9 months after vaccination.) A thorough analysis has been described earlier (Biittiger, Heller & Rollof, 1975) of all joint complaints (time and place). This investigation did not disclose any statistically significant differences between the prevaccination seronegative and the pre-immune vaccinees. A tendency for a higher frequency of complaints of unusual feelings of discomfort in the fingers of the seroconverting girls might, however, be mentioned. A time relationship between menstruation and vaccination has been described (Swartz et al., 1971). The complaints were therefore also analyzed for differences between menstruating and not-yet-menstruating girls. No differences were found, however. The vaccinees were further divided into a younger (12-13 years of age) and an older group (14-15 years) and compared. In general, a slightly lower frequency of complaints (4% lower) was registered in the younger than in the older group. The follow-up
-4 comparison between titres of samples collected during the winters of 1972-73 and 1973-74 showed the following (Fig. 4). During the interval between the two seasons the number of unvaccinated girls with HI-titres of < 1 : 16 had been reduced from 337 to 274, i.e. 15.7% had acquired HI-titres z 1 : 32 during that year. The girls with antibody increases were evenly distributed among the schools. Among 109 vaccinated girls with low postvaccination titres ( < 1 : 16) the number of low-titre ones had been reduced
to 45, i.e. 58.7% had acquired titres 3 1 : 32 during the same period. The distribution of these girls in the schools was comparable
with that of the unvaccinated
group.
111
M.
BdTTIGER
AND
L. HELLER
Non-responding vaccinees 1 ,Posifives
59%
(z= 16)
16%
UnMccinoted COntrOlS I I I
I ; 26%
(6-16)
3%
16% I I 50
loo
Negotives I
I
W3) ,
to--,
I ;
81%
I I I 50
I 0
(%I
Fig. 4. Titre distributions in the winter of 1973-74 of ‘non-responding’ vaccinees (titres C 1 : 16 eight weeks after vaccination in 1972-73) and of unvaccinated girls who in the winter of 1972-73 had displayed similarly low or no antibody titres against rubella.
Revaccinated girls compared with primovaccinated girls Eighty-four girls with no or uncertain postvaccination titres took part in the revaccination performed during the winter of 1973-74 with Almevax; 22 of them had been postvaccination seronegative, 5 had had a HI-titre of 1 : 8 and 57 had had a titre of 1 : 16 8 weeks after the primovaccination. They were bled three times, i.e. at the time of Group I Immune status in 1973:
Revoccinoted
Immediately vaccination
prior to 1974
Vaccination+
IO days after voccinotion 1974
Group 2
Non-responding voccinees
1974
Non-immune unvoccinoted
Primovoccinated
1974
50
0
5 50 @
8 weeks of ter vaccination 1974
(84 girls)
-cd Al
(70
girls)
Al
Fig. 5. HI-titres of girls revaccinated and primovaccinated in 1974 in blood samples collected before vaccination, 10 days and 8 weeks after vaccination. Group 1 (left): Vaccinees with no or uncertain postvaccination antibody response (titres < 1 : 16) 8 weeks after primovaccination in 1973. Group 2 (right): Unvaccinated girls who 1 year earlier were seronegative (66 girls) or had titres of 1 : 16 (4 girls).
112
VACCINATION
AND
REVACCINATION
revaccination, 10 days and 8 weeks after; 70 girls who on the same occasion were primovaccinated with Almevax were bled and tested at similar times; of these 66 had been seronegative and 4 had had a titre of 1 : 16 in the winter of 1972-73. The titre distribution of the two groups prior to any vaccination in 1972-73 did not differ statistically. The results of this second study are illustrated by a series of histograms (Fig. 5). The upper histograms illustrate the HI-titre distribution of the two groups in 1974. The drift described earlier towards higher HI-titres during the intervening year can also be seen in these smaller groups. This drift was likewise significantly more pronounced in the vaccinated than in the unvaccinated group. Forty-nine of the 84 (58.3%) vaccinees and 12 of the 70 unvaccinated girls (17.1%) had acquired titres higher than 1 : 16. This difference was statistically significant (P< 0.01). The histograms in the middle illustrate that in the revaccinated group all but one reacted with an anamnestic response within 10 days after vaccination; among the primovaccinated girls only 4 out of 55 who were seronegative (< 8) prior to vaccination responded to the stimulus within 10 days. The histograms at the bottom illustrate how, after 8 weeks, the antibody patterns of the two groups became quite similar. The geometric mean titre of the revaccinated girls now was 1 : 250 while it was somewhat lower among the primovaccinated, i.e. 1 : 135. COMMENT Primary
antibody response
The initial study indicated that all three vaccines used induced acceptable conversion rates, i.e. higher than 90% (with only prevaccination negative children being counted). However, a difference between the mean titres of the three vaccine groups was found in the samples collected 8 weeks after vaccination. At that time the Almevax vaccine elicited titres half as high as found in the naturally immune girls while the titres of Cendevax and Meruvax vaccinees amounted to one-fourth. The follow-up of the low-titre girls indicated, however, that the peak titres for the Cendevax and Meruvax groups were not reached within 8 weeks. Possibly this also was the case with the Almevax-immunized girls. Thus, in a parallel study carried out in Malmii (Enell, Johnsson & Kullander, 1974), where postvaccination blood samples were not collected until 12 weeks after vaccination, the titre differences between vaccinees and naturally immune girls were less marked. Only the Cendevax girls had lower titre levels. The reason for this late rise in titre might be of interest to study further. Is it caused by live virus still present after 2 months ? Secondary response
Although (or because) we had an indication that our method for measuring antibody titres was quite sensitive, we could not exclude the risk that girls with low titres in fact displayed a non-specific reaction. Thus, it was decided that it would be of interest to study these factors by revaccinating. If the low-titre girls possessed specific antibodies they ought to react with a rapid anamnestic response. This assumption proved correct. Not only did the girls with a low titre respond but also all postvaccination negative girls (with one exception) responded quickly. This response differed completely from that of simultaneously vaccinated but only slowly reacting primovaccinated girls. The follow-up study thus indicates that the general response in all vaccine groups was much better than could be judged from the postvaccination control performed after 8 weeks. These results indicate that only 1 of the 13 tested girls who were 113
M.
BaTTIGER
AND
L. HELLER
seronegative at both 8 weeks and 1 year after vaccination truly lacked immunologic memory. Side-reactions As had already been experienced by many workers in this field, the side-reactions of young rubella vaccinees are negligible. The slight disorders experienced by some of the vaccinees might presumably have become more pronounced after natural infection later in life. PLANNED
FOLLOW-UP
STUDIES
For the future evaluation of the results of general vaccination of schoolgirls several studies are planned which, we hope, will provide adequate information for the future on the benefit of rubella vaccination. REFERENCES Battiger, M., Heller, L. & Rollof, S.-I. (1975). Rubellavaccination av tonirsflickor. Lchrtidningen 71, 1949-S1. Enell, H., Johnsson, T. & Kullander, K. (1974). Rubellavaccination av skolflickor. Lci7wrtidningen 71, 1952-55. Swartz, T. A., Klingberg, W., Goldwasser, R. A., Klingberg, M. A., Goldblom, N. & Hilleman, M. R. (1971) Clinical manifestations according to age, among females given HPV-77 duck rubella vaccine. American Journal of Epidemoogy 94, 246-251.
114
of Biological
Stadurdization
1976 4, 107-114
Experiences from vaccination and revaccination of teenagegirls with three different rubella vaccines* M. Btittigerf
and L. Hellert
The following results were obtained from the vaccination of 3000 schoolgirls between 13 and 14 years of age, with three different rubella vaccines, Ahnevax, Cendevax and Meruvax. Seventy-two per cent of the girls stating a negative rubella anamnesis were found negative in an HI-test against rubella, whereas 33% of the girls claiming to have suffered from rubella were negative. Initially only girls with a negative anamnesis were vaccinated. The antibody conversion rates when calculated only from the initially seronegative girls 8 weeks after vaccination were 97.6% for Almevax, 96.1 o/0 for Cendevax and 91.5?; for Meruvax. The postvaccination geometric mean titre of the Almevax group of primary seronegative girls was 1 : 185 and the corresponding titres of the Cendevax and Meruvax groups were 1 : 82 and 1 : 73. The mean titre of naturally immune girls was 1 : 380 before vaccination. Recognizable reactions of arthritis occurred in less than 1% of the vaccinees. The investigation of the first vaccination trial indicated that all the three vaccines tested gave satisfactory conversion rates in girls seronegative to rubella before vaccination. Sidereactions were negligible. Immunization with Almevax resulted in higher mean titre levels 8 weeks after vaccination than the other two vaccines tested. A follow-up study carried out 1 year later indicated that a number of the girls with low or no demonstrable titres ( d 1 : 16) 8 weeks after the first vaccination had acquired titres 1 : 32 or above during the following year. During the same period the previously unvaccinated group of primari ly seronegative girls showed significantly lower conversion rates. This difference could thus not be explained by the occurrence of natural rubella infections only. Lastly, in contrast to prevaccination seronegative and primovaccinated girls the revaccinated so-called ‘vaccine failures’ generally reacted with a rapid anamnestic response upon restimulation with the virus antigen. These findings indicate that the immune response to the primary vaccination might have been better than shown by the early determined conversion rates.
INTRODUCTION This study was initiated in close cooperation with the Swedish national board of health and welfare in order to obtain the data and experiences necessary to evaluate the immediate and long-term effects of active immunization of schoolgirls against rubella. * Received for publication 19 November 1975. t The National Bacteriological Laboratory, S-105 21 Stockholm,
Sweden.
107
NI. BiiTTIGER MATERIAL
AND AND
L. HELLER METHODS
Three parentally administered rubella vaccines were used, namely Almevax (Burroughs Wellcome), Cendevax (Smith Kline & French) and Meruvax (Merck Sharp & Dohme). They are cultivated on human diploid cells, rabbit kidney cells and duck embryo cells, respectively. The dose injected was the one recommended by the manufacturer. Hemagglutination-inhibition antibody (HIA) titres were determined after treatment of sera with heparin and manganous chloride and by use of erythrocytes of newborn chickens. One ampoule of the international standard serum was suspended in 5 ml of buffer and titrated in parallel. This suspension held a titre of 1 : 32 to 1 : 64. The Jirst vaccination
round
In the autumn of 1972 questionnaires concerning participation in rubella vaccination in Stockholm were distributed to 4000 schoolgirls in the sixth and seventh grade (13-14 years old) and their parents. Three thousand of them declared that they were willing to take part in the study. Half of the girls (Table 1) stated that they probably had had rubella and the other half believed that they had not yet had the disease. TABLE
Girls
with
1. Prevalence of HI-antibodies (titres < 1 : 8) in girls stating positive and negative rubella anamnesis
negative
rubella anamnesis Girls with positiwe rubella
Number of sera tested
Seronegative (HI-titre less than 1 :8)
1324
957
2
365
72.3
1423
471
7
945
33.1
2747
1428
9
1310
52.0
Equivocal (HI-titre =1:8)
Seropositive (HI-titre 1 :16or higher)
Percentage seronegatives
anamnesis
Total population
tested
Initially all the girls were bled for antibody investigations, but only the half with the negative rubella anamnesis was vaccinated during the winter of 1972-73. The vaccinated Questionnaires requesting information half was bled again 8 weeks after the vaccination. on fever, rash, throat disorders and pains in joints or swelling of joints during the postvaccination period were distributed to all vaccinees and also to a number of unvaccinated schoolmates at the time of the vaccination. They were collected after about 6 weeks. The second vaccination
round
The following winter (1973-74) a number of the vaccinees who had not responded to the vaccination, i.e. those with titres less than 1 : 8 or with low titres (1 : 8 or 1 : 16 only) Five of these had been 8 weeks after the immunization, were contacted for revaccination. primary vaccinated with Almevax, 39 with Cendevax and 40 with Meruvax. A number of the girls, who had stated a positive rubella anamnesis but who had been found negative or displaying low antibody titres the year before, were also offered vaccination. All reThe revaccinated girls were bled for vaccinations were performed with Almevax. antibody investigation prior to, 10 days and 8 weeks after vaccination. A number of girls primovaccinated with Almevax were tested likewise. 108
VACCINATION
AND
REVACCINATION
RESULTS The first vaccinations The results of the initial serum investigations are given in Table 1. Seventy-two per cent of the girls with a negative rubella anamnesis lacked demonstrable antibodies (titre < 1 : 8). The corresponding figure of the half claiming to have been infected with rubella was 330/b. The conversion rates from titres < 1 : 8 to titres > 1 : 16 are illustrated in Fig. 1. In all groups the conversion rate 8 weeks after vaccination was above 90%, the girls vaccinated with Almevax showing the highest figure, 97*60,/,.
I
AI~VOX 284/291
100 -
ii!
c&-
Cendevo 299/31
98%
c
Meruvax
1
27W
96%
92%
1 :
Fig. 1. Conversion
rates of prevaccination seronegative girls (proportion titres ( > 1 : 16) 8 weeks after vaccination).
of girls with HI-
The geometric mean titres were 1 : 182, 1 : 82 and 1 : 73 for the Almevax, Cendevax and Meruvax vaccinated girls, respectively (all seronegative prior to vaccination). The titre distributions illustrating also median titres are illustrated in Fig. 2. It can also be seen in Fig. 2 that the girls naturally immune prior to the vaccination had higher titre 100 90 80 70 60Median antibody titres y-J--------------------
40 30 20 IO 4
8
16
32
64
HI-antibody
128
256
512
1024 2048
litre
Fig. 2. Immunologic profiles (accumulated titre distributions) 8 weeks after vaccination of the different groups of vaccinees seronegative prior to vaccination with Almevax (-.--.-) Cendevax (-...-..*-) and Meruvax ( *o*..*) and of naturally immune girls prior to vaccination (-).
109
M.
BOTTIGER
AND
I,. tiEI,I,ISR
levels than those shown by the prevaccination seronegative vaccinees 8 weeks after t& immunization. The booster effect on girls naturally immune prior to the immunization was slightly more marked in girls given Almevax and Meruvax compared with the Cendevax group (Table 2). Variations between different batches were also evaluated (Fig. 3). No statistical differences were found between the pairs of batches used for vaccination with each vaccine.
TABLE 2. Effect of booster in girls with HI-titres
2 1 : 16
Proportion of girls showing fourfold antibody rise after vaccination*
Vaccine
23/123 22/123 7/104
Almevax Meruvax Cendevax
(18.7%) (17.9%) ( 6.7%)
* The difference between Cendevax and the other two vaccines was significant at the
P
r AkWVOX
Cendevax
Meruvox 15/154 -
IO -
5-
51152
7/170 -
Lot I
Lot 2
Lot I
Lot 2 _
Fig. 3. Comparison between batches. Proportions of rubella susceptible girls (prevaccination seronegative) seroconverting 8 weeks after vaccination with different batches of the three vaccines tested.
Side-reactions Reported postvaccination reactions are listed in Table 3. Unfortunately it was not possible to include a placebo group for these evaluations. It can be seen, however, that there were no significant differences concerning fever, rash, throat and joint complaints between girls seronegative or seropositive prior to vaccination. Unvaccinated schoolmates had complaints of the same magnitude during the same period. Only joint complaints differed between vaccinated and unvaccinated. Twenty of the vaccinees stated that they had felt some swelling of the joints (Table 4). School nurses had been especially requested to report immediately about such symptoms. Three cases were reported and inspected by a physician during the actual postvaccination period. Two of them had the migrating but soon disappearing swellings described as typical (Swartz, Klingberg, Goldwasser, Klingberg, Goldblom & Hilleman, 1971) to appear after rubella vaccination. One girl contracted arthritis following a diagnosed streptococcal infection of the throat. 110
VACCINATION
AND
REVACCINATION
TABLE 3. Percentage of girls reporting different symptoms during the 6-week period following vaccination Vaccinated girls
Complaint
r Cendevax (%I
Fever Rash Throat symptoms Joint symptoms
17 10 32 17
Seroconverting A Almevax (%I
yeir;vax 0 0
,
Preimmune (all vaccines) (%I
12 9 31 15
20 7 28 13
16 11 33 16
TABLE 4. Prevalence of complaints
reporting
Prevaccination seronegative Prevaccination immune Seronegative
after vaccination
18 4 29 5
swelling of joints after vaccination
Total Type of vaccine
Unvaccinated girls (%I
Swollen joints ,-*-,
Vaccine
No.
No.
01’ 10
Almevax
284 299 278 350 46
4 5 6 3 1
1.4 1.7 2.2 0.9 2.2
Cendevax Meruvax All vaccines 9,
(Cultures from her knee-joint were negative for rubella, as well as her antibody titres to rubella 2 and 9 months after vaccination.) A thorough analysis has been described earlier (Biittiger, Heller & Rollof, 1975) of all joint complaints (time and place). This investigation did not disclose any statistically significant differences between the prevaccination seronegative and the pre-immune vaccinees. A tendency for a higher frequency of complaints of unusual feelings of discomfort in the fingers of the seroconverting girls might, however, be mentioned. A time relationship between menstruation and vaccination has been described (Swartz et al., 1971). The complaints were therefore also analyzed for differences between menstruating and not-yet-menstruating girls. No differences were found, however. The vaccinees were further divided into a younger (12-13 years of age) and an older group (14-15 years) and compared. In general, a slightly lower frequency of complaints (4% lower) was registered in the younger than in the older group. The follow-up
-4 comparison between titres of samples collected during the winters of 1972-73 and 1973-74 showed the following (Fig. 4). During the interval between the two seasons the number of unvaccinated girls with HI-titres of < 1 : 16 had been reduced from 337 to 274, i.e. 15.7% had acquired HI-titres z 1 : 32 during that year. The girls with antibody increases were evenly distributed among the schools. Among 109 vaccinated girls with low postvaccination titres ( < 1 : 16) the number of low-titre ones had been reduced
to 45, i.e. 58.7% had acquired titres 3 1 : 32 during the same period. The distribution of these girls in the schools was comparable
with that of the unvaccinated
group.
111
M.
BdTTIGER
AND
L. HELLER
Non-responding vaccinees 1 ,Posifives
59%
(z= 16)
16%
UnMccinoted COntrOlS I I I
I ; 26%
(6-16)
3%
16% I I 50
loo
Negotives I
I
W3) ,
to--,
I ;
81%
I I I 50
I 0
(%I
Fig. 4. Titre distributions in the winter of 1973-74 of ‘non-responding’ vaccinees (titres C 1 : 16 eight weeks after vaccination in 1972-73) and of unvaccinated girls who in the winter of 1972-73 had displayed similarly low or no antibody titres against rubella.
Revaccinated girls compared with primovaccinated girls Eighty-four girls with no or uncertain postvaccination titres took part in the revaccination performed during the winter of 1973-74 with Almevax; 22 of them had been postvaccination seronegative, 5 had had a HI-titre of 1 : 8 and 57 had had a titre of 1 : 16 8 weeks after the primovaccination. They were bled three times, i.e. at the time of Group I Immune status in 1973:
Revoccinoted
Immediately vaccination
prior to 1974
Vaccination+
IO days after voccinotion 1974
Group 2
Non-responding voccinees
1974
Non-immune unvoccinoted
Primovoccinated
1974
50
0
5 50 @
8 weeks of ter vaccination 1974
(84 girls)
-cd Al
(70
girls)
Al
Fig. 5. HI-titres of girls revaccinated and primovaccinated in 1974 in blood samples collected before vaccination, 10 days and 8 weeks after vaccination. Group 1 (left): Vaccinees with no or uncertain postvaccination antibody response (titres < 1 : 16) 8 weeks after primovaccination in 1973. Group 2 (right): Unvaccinated girls who 1 year earlier were seronegative (66 girls) or had titres of 1 : 16 (4 girls).
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VACCINATION
AND
REVACCINATION
revaccination, 10 days and 8 weeks after; 70 girls who on the same occasion were primovaccinated with Almevax were bled and tested at similar times; of these 66 had been seronegative and 4 had had a titre of 1 : 16 in the winter of 1972-73. The titre distribution of the two groups prior to any vaccination in 1972-73 did not differ statistically. The results of this second study are illustrated by a series of histograms (Fig. 5). The upper histograms illustrate the HI-titre distribution of the two groups in 1974. The drift described earlier towards higher HI-titres during the intervening year can also be seen in these smaller groups. This drift was likewise significantly more pronounced in the vaccinated than in the unvaccinated group. Forty-nine of the 84 (58.3%) vaccinees and 12 of the 70 unvaccinated girls (17.1%) had acquired titres higher than 1 : 16. This difference was statistically significant (P< 0.01). The histograms in the middle illustrate that in the revaccinated group all but one reacted with an anamnestic response within 10 days after vaccination; among the primovaccinated girls only 4 out of 55 who were seronegative (< 8) prior to vaccination responded to the stimulus within 10 days. The histograms at the bottom illustrate how, after 8 weeks, the antibody patterns of the two groups became quite similar. The geometric mean titre of the revaccinated girls now was 1 : 250 while it was somewhat lower among the primovaccinated, i.e. 1 : 135. COMMENT Primary
antibody response
The initial study indicated that all three vaccines used induced acceptable conversion rates, i.e. higher than 90% (with only prevaccination negative children being counted). However, a difference between the mean titres of the three vaccine groups was found in the samples collected 8 weeks after vaccination. At that time the Almevax vaccine elicited titres half as high as found in the naturally immune girls while the titres of Cendevax and Meruvax vaccinees amounted to one-fourth. The follow-up of the low-titre girls indicated, however, that the peak titres for the Cendevax and Meruvax groups were not reached within 8 weeks. Possibly this also was the case with the Almevax-immunized girls. Thus, in a parallel study carried out in Malmii (Enell, Johnsson & Kullander, 1974), where postvaccination blood samples were not collected until 12 weeks after vaccination, the titre differences between vaccinees and naturally immune girls were less marked. Only the Cendevax girls had lower titre levels. The reason for this late rise in titre might be of interest to study further. Is it caused by live virus still present after 2 months ? Secondary response
Although (or because) we had an indication that our method for measuring antibody titres was quite sensitive, we could not exclude the risk that girls with low titres in fact displayed a non-specific reaction. Thus, it was decided that it would be of interest to study these factors by revaccinating. If the low-titre girls possessed specific antibodies they ought to react with a rapid anamnestic response. This assumption proved correct. Not only did the girls with a low titre respond but also all postvaccination negative girls (with one exception) responded quickly. This response differed completely from that of simultaneously vaccinated but only slowly reacting primovaccinated girls. The follow-up study thus indicates that the general response in all vaccine groups was much better than could be judged from the postvaccination control performed after 8 weeks. These results indicate that only 1 of the 13 tested girls who were 113
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seronegative at both 8 weeks and 1 year after vaccination truly lacked immunologic memory. Side-reactions As had already been experienced by many workers in this field, the side-reactions of young rubella vaccinees are negligible. The slight disorders experienced by some of the vaccinees might presumably have become more pronounced after natural infection later in life. PLANNED
FOLLOW-UP
STUDIES
For the future evaluation of the results of general vaccination of schoolgirls several studies are planned which, we hope, will provide adequate information for the future on the benefit of rubella vaccination. REFERENCES Battiger, M., Heller, L. & Rollof, S.-I. (1975). Rubellavaccination av tonirsflickor. Lchrtidningen 71, 1949-S1. Enell, H., Johnsson, T. & Kullander, K. (1974). Rubellavaccination av skolflickor. Lci7wrtidningen 71, 1952-55. Swartz, T. A., Klingberg, W., Goldwasser, R. A., Klingberg, M. A., Goldblom, N. & Hilleman, M. R. (1971) Clinical manifestations according to age, among females given HPV-77 duck rubella vaccine. American Journal of Epidemoogy 94, 246-251.
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