a case study of measles vaccination for university students during the measles outbreak in tokyo,...

ORIGINAL ARTICLE

A case study of measles vaccination for university studentsduring the measles outbreak in Tokyo, Japan, 2007

Ryuichi Fujisaki • Mariko Yamamura • Shigeru Abe •

Kousuke Shimogawara • Michihiro Kasahara •

Hajime Nishiya • Miho Makimura • Koichi Makimura

Received: 16 December 2010 / Accepted: 25 October 2011 / Published online: 3 December 2011

� Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases 2011

Abstract In April 2007, seven students belonging to the

same class at Teikyo University developed measles. To

prevent the spread of infection, 27 of 106 students in the

same class who had low anti-measles antibody titers as

measured by hemagglutination inhibition (HI) assay were

vaccinated. After the outbreak had subsided, the HI values

were investigated in 103 students, and they answered

questionnaires about their health condition during the

period of the outbreak and their previous clinical histories

of measles, including vaccination records. There was no

new case of measles after introduction of the vaccination

program. However, the HI titers of 42% of the students

who were not vaccinated in this program were significantly

elevated. Fever and catarrhal signs occurred in 7 of these

students with pre-exposure titers of 8 or less. The post-

exposure HI titers of 71% of students who were unaffected

by measles and had high HI titers ([8) before the epidemic

did not increase. These results suggested that people with

low HI titers may become potential carriers of measles and

that measurement of pre-exposure HI anti-measles anti-

body titer is a useful method for selection of candidates to

undergo vaccination.

Keywords Measles � Vaccination � Outbreak �Student � Hemagglutination inhibition (HI) �Enzyme immunoassay (EIA)

Introduction

Measles virus causes acute infectious disease in humans [1,

2] and is the etiological agent one of the most important

lethal infections in young children. Measles infection

shows several clinical signs, i.e., cough, coryza, high fever,

maculopapular rash, conjunctivitis, and complications of

pneumonia and/or encephalitis in some cases, which

occasionally results in death. In 2001, there was a nation-

wide outbreak of measles in Japan. Most patients affected

in this outbreak were infants and young children [3]. Fol-

lowing this measles outbreak, the government of Japan

strengthened the measles surveillance system in each pre-

fecture and promoted a nationwide campaign of vaccina-

tion for children. These attempts resulted in a marked

reduction in the measles infection rate among younger

people. However, in 2006 a small local prevalence of

R. Fujisaki

Emergency Room of Teikyo University Hospital, 2-11-1 Kaga,

Itabashi-ku, Tokyo 173-8605, Japan

M. Yamamura

Department of Internal Medicine, Faculty of Medicine, Teikyo

University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan

S. Abe � M. Makimura � K. Makimura (&)

Teikyo University Institute of Medical Mycology, Teikyo

University, 356 Otsuka, Hachioji, Tokyo 192-0395, Japan

e-mail: [email protected]

K. Shimogawara

Laboratory of Chemistry, Faculty of Medicine, Teikyo


M. Kasahara

Laboratory of Biophysics, Faculty of Medicine, Teikyo


H. Nishiya

School of Medical Technology, Teikyo University, 2-11-1 Kaga,


K. Makimura

Laboratory of Space and Environmental Medicine,

Graduate School of Medicine, Teikyo University, 2-11-1 Kaga,


123

J Infect Chemother (2012) 18:341–346

DOI 10.1007/s10156-011-0343-x

measles led to an outbreak in Japan that lasted until the

summer of 2007 [3]. The outbreak in 2007 was different

from previous outbreaks in that the majority of patients

were young adults or adolescents attending high schools

and university students [3–7].

Measles vaccination in Japan started in 1978. The

majority of people born before 1978 had no history of

measles vaccination, but their antibody titers against

measles are sufficiently high to avoid infection, which can

be explained by natural sensitization to measles. Younger

generations show reduced levels of antibodies against

measles [3, 4], which is considered to be caused by the

decrease in the opportunity for natural sensitization and

lack of complete vaccination. From 2006, two dosage

schedules were started, at 1 year and at 5–6 years of age,

but this system could not prevent the measles outbreak in

summer of 2007. The Japanese government implemented a

5-year vaccination catch-up campaign for cohorts aged 13

and 18 years to prevent future outbreaks of measles [3]

from 2008. However, complete vaccination in this gener-

ation seems not to be actually possible for social and

economic reasons. In addition, some persons avoid vacci-

nation because of highly publicized problems with measles,

mumps, and rubella (MMR) vaccine between 1989 and

1993 in Japan [8]. Practically, it is necessary to present

reasonable criteria of vaccination.

In this study, we used the hemagglutination inhibition

(HI) test for measurement of antibody activity against

measles. The HI test is generally less sensitive than enzyme

immunoassay (EIA) [9]. However, HI is a simpler and

lower-cost method than EIA. In addition, the HI test does

not require specialized instruments or techniques and

can therefore be introduced conveniently into small

laboratories.

Here, we investigated pre- and post-HI titers of 103

students exposed to a measles outbreak. The clinical con-

dition and previous history of measles and vaccine records

of all subjects were also investigated.

Materials and methods

Background

During the period from March to May 2007, 7 students in

the first grade of the Faculty of Medicine on Teikyo Uni-

versity Hachioji campus developed measles. A total of 106

students belonged to the same class. The first case was

observed in March, and the last case was detected on April

29. The university is located in the eastern part of Tokyo;

the students of the medical school all belonged to the same

class and were isolated from other students from different

departments by their special lecture schedule. They also

lived within a very limited area around the university.

Study population

A total of 103 of the 106 students provided informed

consent to participation in this study. The average age of

subjects was 22 years old. These 103 subjects included 7

students who developed measles.

Titration of antibodies against measles by HI test

and EIA (serological tests)

The anti-measles antibody titers of the first-grade medical

school students were measured by hemagglutination inhi-

bition (HI) test [7] before the beginning of their first school

session (10 April 2007). These results were used as the pre-

exposure titers. HI tests performed using commercial kits

obtained from SRL (Tokyo, Japan) involved measuring HI

titers by testing endpoint serial dilution of blood samples

for hemagglutination inhibition. In this study, an increase

in post-exposure HI titers of more than fourfold compared

to the pre-exposure value was determined to be significant.

Post-exposure blood samples were obtained on June 11,

when we confirmed the end of the measles epidemic at this

university because no new patient had been observed for

1 month. The blood samples of 103 subjects were inves-

tigated as post-exposure titers by HI test and EIA (SRL).

Clinical condition and vaccination history

Information from participants concerning symptoms

experienced during the outbreak was obtained by self-

administered questionnaires. Signs and symptoms elicited

on the questionnaire included fever and catarrhal symp-

toms (cough, runny nose, red watery eyes or light sensi-

tivity, sore throat), headache, and diarrhea. Information

about previous and recent vaccinations and measles history

were obtained from students, parents, and provider-verified

birth records.

Vaccination

There was a serious shortage of measles vaccine in Japan in

spring 2007. Some students who wished to receive the

vaccination could not do so because of insufficient avail-

ability of the vaccine. The 27 subjects with low HI titers

(\8) and 5 with HI titers C8 who strongly desired vacci-

nation had the vaccination between April 21 and June 3; a

total of 32 subjects were vaccinated (one time/person).

342 J Infect Chemother (2012) 18:341–346

123

Results

Measles patients (cases)

The data for seven students diagnosed with measles during the

period between March and May 2007 are shown in Table 1.

One student (case 6) developed measles illness between

March 26 and April 7 and was considered to have recovered

from the illness before collection of the pre-exposure blood

sample (Table 1). Case 1 showed mild clinical signs of

measles at pre-exposure blood sample collection and may

have been in the very early stages of infection at this point.

Pre-exposure samples from all cases had low titers (\8)

of HI, except for case 6, who had recently recovered from

measles. The post-exposure titers of six students diagnosed

with measles (all positive cases except case 6) significantly

increased (4- to 128-fold higher than pre-exposure titers).

The clinical manifestations in these cases were all consis-

tent with classical measles symptoms, i.e., fever, confluent

maculopapular rash, and cough, coryza, or conjunctivitis.

Pre-exposure HI titers: comparison between cases

and non-cases

Six of the seven students affected with measles after pre-

exposure sampling had the lowest HI titers (\8). Subjects

who did not have clinical measles had antibody titers

ranging from\8 to 256 (data not shown). Fifty-seven of 96

students had HI titers B8 (59%). Thirty-nine students

(41%) had HI titers [16 [HI titer: 256 (n = 1), 128

(n = 6), 64 (n = 1), 32 (n = 11), 16 (n = 20) (data not

shown)]. The average HI titers in cases and non-cases were

8 and 23, respectively.

Pre- and post-exposure HI titers: non-cases

The increase in HI titer of non-cases was investigated

(Table 2). In the vaccine group (32 students), 24 subjects

(75%) showed increases in HI titer of more than fourfold

compared to the pre-exposure value. None of the subjects

with pre-exposure titers [8 showed an increase in post-

exposure titer. In the non-vaccinated group (64 students),

27 subjects (42%) showed increases in HI titer of more

than fourfold compared to the pre-exposure value. Non-

vaccinated subjects with pre-exposure titers of 8 or less

included 7 who showed both fever and catarrhal signs

(Table 2). Only 1 non-vaccinated student with a titer \8

showed fever (Table 2).

Comparison of the results of HI test with those of EIA

We compared the results of HI test and those of EIA using

all post-exposure blood samples (Fig. 1). The HI titers of

subjects were closely correlated to the values determined

by EIA.

Table 1 Hemagglutination inhibition (HI) titer and clinical infor-

mation of cases

Case Pre

titer

Post

titer

Previous

measles

Previous

vaccinations

Measles illness

1 \8 256 – Unknown April 7–April 14

2 \8 1,024 – 0 April 25–May 5

3 \8 1,024 – Unknown April 25–April 30

4 \8 32 – 0 April 22–April 28

5 \8 512 – Unknown April 22–May 2

6 32 64 – 0 March 26–April 7

7 \8 1,024 – 1 April 23–April 28

Pre titer, pre-exposure titer; Post titer, post-exposure titer

Table 2 Change of hemagglutination inhibition (HI) titer in non-

cases

Non-case (n = 96) C4 fold \4 fold

Vaccinated (n = 32)

Pre titer \8 22 (7/2)a 5 (1/0)

Pre titer = 8 2 (0/0) 0

Pre titer [8 0 3 (0/0)

Non-vaccinated (n = 64)

Pre titer \8 2 (2/2) 1 (0/0)

Pre titer = 8 14 (5/5) 11 (1/0)

Pre titer [8 11 (1/0) 25 (5/1)

a Clinical signs: catarrh/fever

Pre titer, pre-exposure titer

Fig. 1 Comparison of titers determined by hemagglutination inhi-

bition (HI) and enzyme immunoassay (EIA). The HI and EIA titers of

103 individuals are expressed as small points (small filled circles).

Average values are expressed as large symbols (large filled circles).

Standard differences are indicated by vertical bars

J Infect Chemother (2012) 18:341–346 343

123

Relationships between previous vaccinations

and history of measles and resistance to infection

In this study, the students who had histories of measles

infection and with records of vaccination with two doses

did not develop typical measles illness (Table 3). However,

history of measles and number of previous vaccinations

were not related to pre- or post-exposure HI titers in either

cases or non-cases.

Discussion

Sporadic outbreaks of measles occurred in Japan from 2006

to 2007 [3–7]. In many cases, outbreaks were reported

from distinct capitals, and occurred in schools with stu-

dents aged 10–20 years old. There have been several

reports regarding phylogenetic analysis of measles virus

[5–7]. However, there have been few reports of pre- and

post-exposure anti-measles antibody levels. Chen et al.

[10] reported a large-scale measles epidemic in the dor-

mitories of Boston University (USA). They investigated

pre- and post-exposure blood samples and reported changes

in specific anti-measles antibody using EIA and the plaque

reduction neutralization (PRN) test.

In this study, we collected serological and clinical

information for 103 students exposed to measles and

investigated the effects of vaccination in students with low

levels of anti-measles antibody to establish a concrete

strategy for preventing the expansion of measles outbreaks.

Significance of pre-exposure HI titer

The presence of detectable measles antibody has been

thought to indicate that an individual would be protected

against falling ill if exposed to the measles virus. However,

there have been only a few reports regarding pre-exposure

anti-measles antibody titer [10, 11].

In this study, we used the HI test for measurement of

anti-measles antibody titers. The standard HI test, a

traditional assay, is less sensitive than EIA and the PRN

assay [9, 12, 13]. However, the HI test can be performed

easily and does not require special techniques or expensive

equipment. Thus, we gave priority to the convenience,

rapidity, and practical applicability of the HI test.

The results of the present study using the HI test sug-

gested that a titer [8 was required for protection against

measles. All patients in this study had HI pre-exposure titers

\8, with the exception of case 6 who had recently recovered

from illness before pre-exposure sampling. The 30 subjects

who had low pre-exposure titers (\8) did not develop

measles (Table 2). Using the PRN assay, Chen et al. [10]

suggested that a titer [120 mIU/ml was required for pro-

tection against falling ill with measles. The number of

patients in our study was too small to determine the border

value; however, at least the subjects whose pre-exposure HI

titer was\8 were susceptible to measles infection.

Post-exposure HI titers

From the point of view of post-exposure titer change, the

103 students were divided into three groups: group 1

consisted of 7 cases of measles; group 2 consisted of 51

non-cases whose post-HI titers increased by more than

fourfold; and group 3 consisted of 45 non-cases whose post

HI titers did not increase. The subjects in group 2 had pre-

exposure HI titers \8 (47%), 8 (31%), and [8 (22%). On

the other hand, 13%, 24%, and 62% of subjects in group 3

had pre-exposure HI titers \8, 8, and [8, respectively.

Group 2 included 9 subjects who showed fever and catar-

rhal signs during the epidemic period; group 3 included

only 1 of these subjects. Comparison of the results sug-

gested that the students in group 2 responded to vaccination

and/or measles virus, and the subjects with low pre-expo-

sure titers (B8) were more affected by the measles than

those with high pre-exposure titers ([8). Interestingly, the

questionnaires regarding the relationships between students

revealed detailed behavioral patterns of students, and these

actions were related to the division into groups 2 and 3

(data in preparation for publication).

Table 3 Previous measles and vaccination history of cases and non-cases

Case of measles Pre titer Post titer Clinical signs

\8 =8 [8 \4-fold C4-fold

Previous measles (n = 11) 0 4 1 6 5 6 2

Previous vaccine, 0 (n = 10) 3 3 0 7 4 6 3



Unknown (n = 30) 3 10 8 12 15 15 4

Clinical signs: catarrh and/or fever

Pre titer, pre-exposure titer; Post titer, post-exposure titer


123

Reliability of HI test in comparison with EIA

Several reports have measured the antibody against mea-

sles by HI test, EIA, or enzyme-linked immunosorbent

assay (ELISA) [14–18]. Many of these reports suggested

the HI test was lower in sensitivity than EIA because false-

negative results were demonstrated in the HI test. How-

ever, as the HI test is cheaper than other methods, such as

EIA and the plaque neutralization (PRN) test, it is a more

useful method for wide-scale epidemical investigation than

other methods.

To investigate the reliability of the HI test, we compared

the HI test results with these of EIA using all 103 post-

exposure blood samples. The HI titer and the EIA titer of

the same samples were closely correlated; suggesting that

titer as measured by HI test reliably reflects the trend of

measles antibody.

Effects of vaccination during measles epidemic

Twenty-four (75%) subjects who were vaccinated during

the period from April 21 to June 3 showed increases of

more than fourfold in post-exposure HI titer. However, 8

students who were vaccinated did not show such increase.

Five of them were vaccinated at least 1 month before the

collection of post-exposure samples, and 3 other persons

were vaccinated later, but all of them had a history of

previous vaccination (data not shown). Thus, the reason for

the low titers in these 8 cases is unknown. One possible

inference is that in some cases vaccination is not enough to

induce anti-measles antibody production. For sufficient

induction of anti-measles antibody, additional stimulation,

such as contagion with measles virus, may be necessary.

In this study, because the supply of the vaccine was

limited, 3 students with pre-exposure HI titers below 8

were not vaccinated. Two of them showed fever and cat-

arrhal signs, and their post-exposure titers were signifi-

cantly increased. Also, 14 students with pre-exposure titers

B8 showed increase in their post-exposure titers and

developed fever and/or catarrhal signs during the epidemic.

On the other hand, 3 students who were vaccinated and had

pre-exposure HI titers greater than 8 did not show signifi-

cant increases in post-exposure titer and had no clinical

signs. These results suggested that people with low pre-

exposure titers (B8) would require the vaccine, and those

with pre-exposure titers [8 would not require the vaccine

for protection against viral infection.

Clinical signs

Previous reports have described modified atypical measles

in children and young adults [19–21]. The clinical signs of

mild measles are very similar to these of the common cold

and pollinosis except for the high fever and rash. In our

study, 22 of the non-cases had catarrhal signs (cough,

runny nose, red watery eyes or light sensitivity, sore throat)

and 10 showed these signs combined with mild fever. Nine

of these subjects with pre-exposure titers B8 showed sig-

nificant increased in their post-exposure titers. These 9

students apparently responded to vaccine and/or measles

virus, and were suspected to have mild nonclassic measles,

resembling modified measles. The students whose post-

exposure titers did not increase may not have been affected

by the vaccine or measles virus, so their clinical signs

would be derived from other diseases, such as pollinosis or

the common cold. We cannot conclude that the clinical

signs observed in the students whose post-exposure titers

increased significantly were derived from measles. There

are several other possibilities: pollinosis, general infection

caused by various pathogens, and side effects of vaccina-

tion. Generally the catarrhal signs, such as excess mucous

secretion and inflammation, increase the risk of spreading

pathogens. Basic care such as handwashing and wearing

masks are recommended for practical protection among

individuals.

Previous vaccination and history of measles

Traditionally, it has been thought that once the immune

system has been stimulated by wild measles virus, immu-

nity will persist for life. Some reports agreed with this

proposal [10, 22], whereas others suggested the possibility

of reinfection and indicated the defective protection against

measles infection in subjects with a history of prior

infection with wild measles virus or a complete vaccination

history [23, 24]. In the present study, subjects with a prior

history of measles infection or with a record of two vac-

cinations did not develop measles. These results support

the traditional theory of measles. The pre- and post-expo-

sure HI titers of students with a history of measles or with

two prior vaccinations were not different from those of

other students. The number of vaccinations was not related

to changes in HI titer or clinical signs. More information is

required to discuss the necessary number of vaccinations.

Our results support the plan for a two-dose measles vac-

cination schedule as recommended by the World Health

Organization (WHO) and Centers for Disease Control

(CDC) [2–4, 10].

Conclusion

Determination of pre-exposure HI titer is a reliable and

practical method for identifying suitable candidates for

measles vaccination. Our results indicated that vaccination

during a measles epidemic succeeded in inducing anti-

J Infect Chemother (2012) 18:341–346 345

123

measles antibody production. Subjects with pre-exposure

HI titers of 8 or less are recommended for measles vacci-

nation to avoid individual infection and to prevent the

expansion of measles infection within the community.

The results of this study provided additional information

for future measles control in Japan.

Acknowledgments The authors thank the staff and students of the

Faculty of Medicine of Teikyo University for their participation and

cooperation in this study.

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a case study of measles vaccination for university students during the measles outbreak in tokyo,...

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