Jpn. J. Infect. Dis., 54, 184‑188, 2001

Epidemiological Report

Evaluation of a Mass Influenza Vaccination Campalgn
Hiroshi Takahashi*, Yayoi Tanakal , Takaaki Ohyama, Tomimasa Sunagawa2,
Kazutoshi Nakashima2, George P. Schmid3 and Nobuhiko Okabe
lnfectious Disease Surveillance Center and lField Epidemiology Training Program,
Na tional Institute of lnfectious Diseases,

Toyama ll23‑1, Shinjuku‑ku, To&0 162‑8640,

2Department of lnternational Medicine, Kawaura Town Hospital,
Kumamoto 863‑1215, Japan and
3 world Health Organization,
1211 Geneva 27, Switzerland(Received April 5, 2001. Accepted October 2, 2001)

SUMMARY: Kawaura, a rural town in Kumamoto Prefecture, Japan, population approximately 6,800, started amass influenza vaccination campalgn in the 199912000 season for all residents ≧3 years of age. The town provided

free vaccinations to children ≦13 years and the elderly ≧65 years. Only 900 yen (US$8.80) was charged to theother residents f♭r two vaccinations. ln the 1 999‑2000 season, a total or 5,563 doses of vaccine were administered

to 2,952 residents. Over 90% of the vaccinees received two doses. The program resulted in a vaccination rate of
43% ofall residents. The vaccination rates for females and males were 40.7% and 36.8%, and for those of3‑14
years, 15‑64 years, and ≧65 years population were 75%, 3 1%, and 55%, respectively. The town spent a total of

5.78 million yen (US$56,700) for the campaign. The per‑shot cost was estimated as 1,683 yen (US$16.50).

From December 1999 through March 2000, a total of233 town residents (15‑101 years old, median 72) wereadmitted to the town hospital･ Of the 233 inpatients, 22 (66‑98 years old, median 78) developed respiratory
illness, with 4 fatal outcomes. Ofthese 22 cases, 3 had been vaccinated twice, while I 9 had not been vacclnatedat all. The relative risk of vaccinees'hospitalization due to resplratOry illness decreased to 0. 1 3 compared withthat ofnon‑vaccinees (3/I ,203 versus 19/1 ,003, vaccine efficacy ‑ 0.87). Likewise, the relative risk ofvaccinees
death due to respiratory illness decreased to 0.28 compared with that ofnon‑vaccinees (I/1 ,203 versus 3/1 ,003).

The results of the Kawaura town's initiative should be helpful for better modeling of mass innuenza vaccination
CampalgnS･lation are lower than those in other industrialized countries.

lNTRODUCTION

Followlng the 1 992 abandonment of widespread vaccination

The magnitude of the efficacy of influenza vaccines hasof school children, the vaccine distribution in 1 995 was only

been vlgOrOuSly debated in Japan. This debate has fbcused

8 doses per 1 ,000 Population (7), one thirtieth that of the U.S.

on how well vaccinations protect the elderly, the group mostWhy low influenza vaccination rates persist in Japanese

at risk of severe illness and death. It is commonly believed

elderly population despite data from Japan and other industri‑that the diminished immune systems or the elderly may

alized countries supportlng Vaccination lS Puzzling. lt is clear

respond to innuenza vaccines, but conflicting results havethat excess death of the Japanese elderly during innuenza

been published concermng sufficient immune protection of
antibody response to influenza vaccine in the elderly, however,seasons is slgnificant, especially since A/H3 strains havebecome epidemic (8). Among the elderly in the U.S., it isestimated that more than 40% of the 1 10,000 hospitalizations

have shownrises in antibody levels similar to those in younger

are related to influenza during an average innuenza season,

individuals (2,3), and, more important, protection kom illness

and也at more than 90% of血e 20,000 dea血s are associated withthe elderly compared to young subjects ( I ). Japanese studies ofinfluenza (9). Were vaccination rates not so high, morbidity(214). These and similar data in many industrialized countries
have indicated the desirability of widespread vaccination orolder adults and the elderly. ln the United States (U.S.), 67%

and mortalitywould be worse, and the U.S. Centers for Disease
Control and Prevention (CDC) estimates that for.every 1of the population ≧65 years of age was vaccinated in prepara‑

million elderly persons vaccinated, 1 ,300 hospitalizatlOnS andtion for the 1998‑1999 influenza season (5). For the 1999‑

900 deaths are averted.

2000 season, over 77million doses of vaccine were produced

Although the elderly, who are most likely to contract

for the U.S. population of274 million (6). In 1995, the U.S.

microbial infections, benefit the most from influenza vaccina‑

had a vaccine distribution of239 doses per 1000 population

tion, other groups are also protected by vaccination. The U.S.

(7)･ In contrast, in Japan, in preparation fわr the 1999‑2000

guidelines recommend vaccination of those ≧50 years of age

innuenza season, some 3.5 million vials of vaccine werewith a variety of chronic illnesses (9). Healthy, younger

produced fわr the Japanese population of 1 27 million (Fig. 1 ).

Japanese vaccination rates among the elderly and general popu‑

people, however, are also protected by vaccination, andwhether one vaccinates these groups is largely a matter of*Corresponding author: Tel: +81‑3‑5285‑1 1 I I ext. 2538, Fax: +81‑

cost‑effectiveness and individual preference.
One reason why vaccination of the Japanese population,

3‑5285‑1 129, E‑mail: hiroshit@nih.go.jp

especially the elderly, lS not more Strongly supported may be

184pa3npOJdt Z!^au. 63｡AdZuanUu!

2000

1 ,400,000

1800
1 ,200,000

1600
1 ,000,000(ooo'olx) 1400
1200

Agtv ua!t Zdnt

800,000

1 ()00600,000

800
600

400,000

400
200,000200
00986t＼れ861

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Controversy w ithdrawal
Fig. 1. 1nnuenza vaccine production and pcdiatric inf一uenza‑like illness (ILI) <1 5 years old, 198512001, Japan.

that relatively few Japanese studies of vaccine efficacy have

whether they wished to receive the vaccine or not. Records

been ca汀ied out (4), and that, perhaps as a result, the nationalof these responses were used to plan fわr the purchase of

guidelines in recent years have not strongly endorsed vaccine

sufficient vaccine well in advance of the time it was needed,administration (10).Asthere is little public funding support

as a vaccine shortage was expected. The town designatedfor vaccination and because vaccination is relatively expensive

seven vaccination sites at schools and public venues such as(US$25‑35 per shot), it may be no surprise that tepid national

community centers, which were geographically separated, so

recommendations fわr a relatively expensive vaccine result inthat all citizens, in particular the elderly, Could conveniently

poor vaccination coverage. The high expense of the vaccine
has been caused, in part, by the Japanese policy of using two

be vaccinated on vaccination days.

doses or vaccine administered 1 ‑4 weeks apart compared toordered Influenza HA vaccine (I ml vial contains A/Beijing/

the one‑dose reglmen that is used in other industrialized

262/95 200ccA/ml, A/Sydney/5/97 350ccA/ml, and B/
Shangdong 300ccA/ml; Kaketsuken, Kumamoto) from awholesale distributor. On the vaccination day (November 1 7,

Three months befわre the mass vaccination, Kawaura town

nations. Even assumlngthat an appreciation of vaccine efficacy
becomes more widespread in Japan, the e飴ctiveness of mass

immunization for influenza needs to be established. How does

1 999), volunteers together with town o氏cials, obtained written

one effectively Immunize large sections of the population?

informed consent. ARer taking anamneses and performlng a

And what groups should be targeted?

physical examination, the physician administered the vaccine

Kawaura town is located in arural area of the Amakusa
Peninsula in Kumamoto Prefecture. The town has a popula‑

years of age O･2 ml), accompanied by oヮe or two nurses andsubcutaneously (adults 0.5 m1, 6‑12 years of age 0.3 m1, 3‑5tion of 6,865, which is engaged primarily in agncultural andstaff. Vaccinated persons spent approxlmately 10 min a洗er

丘shery businesses. Severe innuenza activityoccurred in Japan

vaccination at the site to ensure that there were no immediate

during the 1997‑1998 and 1998‑1999 seasons (1 I,12), resultl

hypersensitive reactions to the vaccine. Approximately 4

lng ln COnSiderable morbidity in the town. However, desplte

Weeks after the initial vaccination, residents were eligible forthe increase in the number of deaths associatedwith influenza,

the second dose, and communlty efforts to administer thethe outbreak was not as severe as in other towns, likely because

second dose were similar to those for the first.

residents at the town nurslng home have received influenza

Residents were charged the wholesale cost of the vaccine

vaccinations free of charge for nearly two decades. Followlng(450 yen, or US$4･40 per dose)･ Children ≦13 ye.ars and thethe 1 998‑ 1 999 season, the mayor and town council were startled

elderly ≧65 years of age received the vaccinatlOn free ofby the differences in morbiditybetwe.en the vaccinated andcharge. Because the vaccinations were perf♭med at schools

unvaccinated, and to avoid increase ln morbidity in 1999‑

or communlty Centers, there was no cost for the facilities.

2000, a mass vaccination campalgn Was Planned for all

Distribution and administrative costs as well as the cost or

residents ≧3 years of age fわr 1999‑2000. Through evaluation

synnges, needles and administration were bone by the town.

of this unique effort, We have investlgated questionsconcemlng

Town physicians supported the vaccination effort, and theymass influenza vaccination in Japan.

were paid an hourly rate by the town･During December 1, 1999 through March 3 1, 2000, name,age, sex, period of hospitalization, diagnosis, underlinlng

MATERIALS AND METHODS

conditions, medical expenses, and vaccination record of all

initially, town‑Wide meetlngS Were held to explain thethose ≧15 years who were hospitalized in the town hospitaldecision and to gather support, which became widespread.

were investlgated from clinical charts. None were admitted

Residents were mailed information about the campalgn

anywhere other than the town hospital. Pediatric patients less185

with 4 fatal outcomes. Ofthe 22 cases, 3 had been vaccinatedthan 1 5 years old were not investlgated because most of them

twice, while 19 had not been vaccinated at all. The relative

were referred out of town.

To estimate the vaccine efficacy, a vaccination request hst

risk of vaccinees'hospitalization due to resplratOry illness

used fわr the mass vaccination campalgn Was Categorized

decreased to 0. 1 3 compared with that ofnon‑vaccinees (3/according to those who were immunized and those who were1,203 versus 19/1,003). Among the 4 fatal cases, 1 had been

not･ To c?mpare the attack rate for influenza‑like illness (ILI),

vaccinated twice, while 3 had not. The relative risk of

200 vacclneeS (4‑81 years old, median 45 years old, 95 males,

vaccinees death due to resplratOry illness decreased to 0.28

and 105 females) and 200 non‑vaccinees (3‑84 years old,compared with that ofnon‑vaccinees ( 1 /1 ,203 versus 3/1 ,003).

median 42 years old, 102 males, and 98 females) †ere

Among the I 1 fatal cases due to non resplratOry illness, 3 hadrandomly selected by the local health center from the vacclna‑

been vaccinated, and 8 had not. The relative risk ofvaccinees

tion request list. Those selected residents were requested todeath due to non resplratOry illness decreased to 0.3 1 comparedanswer: 1) how many doses of the vaccine did you receive,with that ofnon‑vaccinees (3/1,203 versus 8/1,003).

and 2) did you experience lLl between December 1999 andOfthe 5,568 town residents ≧1 5 years of age, 2,242 received

March 2000･ lLI was defined as fever >380C with cough or

vaccinations. Among the vaccinees, 27 Were hospltalizedmuscle/joint paln, Plus either headache, appetite loss, or generaldue to non resplratOry illness. The relative risk of vaccinees'

fatigue.

hospitalization due to non resplratOry illness decreased to 0.44

Local influenza activity Was mOnitored by the national

compared with that or non‑vaccinees (27/2,242 versus 91/

influenza sentinel and laboratory surveillance.

3,326). Iffocusing only on the population ≧65 years old, therelative risk decreased to 0.32 (26/1,203 versus 68/1,003)(Table 1).

RESUIXS

Among the 200 vaccinees and 200 non‑Vaccinees selected

A total of 5,563 doses of vaccine were administered to 2,952

for vaccination and lLI queries, a total of241 (60.25%), aged

residents aged ≧3 years. The program resulted in a vaccina‑

4178 years (median 39 years old, 108 males and 133 females)

tion rate of43% for all residents. The female vaccination rate

responded. Of these, 3 receivlng two Vaccinations presented(40･7%) was higher than that fわr males (36.8%). The vaccina‑

ILI, 1 12 receivlng two Vaccinations did not present ILI, 5tion rates of the population aged 3‑ 14 years, 1 5‑64 years, andreceivlng a Slngle vaccination presented ILl, 4 1 receivlng a≧65 years were 75%, 3 1%, and 55%, and the vaccination rates

slngle vaccination did not present ILI, 4 recelVlng nO Vaccina‑

according to the fわur comunities were 35.3%, 37.7%, 40.4%,

tion presented ILl, and 66 receivlng nO Vaccination did not

and 40･6%, respectively (those who stayed at the hospital andnurs.ing facilities were excluded)･ Over 90% of individuals

present ILI･ Ten responses were invalid. The vaccine etrlCaCy
for those receivlng two doses of vaccine was estimated to be

54%. Likewise, the vaccine efficacy for those receivlng
either one or two doses of vaccine was calculated to be 1 3%.

recelVlng One dose of vaccine received a second. Except f♭r

local reactions such as soreness and redness (3), no severe

adverse effects were reported.
The town spent a total of 5.78 million yen (US$56,700)

However, these results were not statistically significant (Table2).

for the mass vaccination. The per‑shot cost was estimated as

The medical costs were estimated based on the medical

1,683 yen (US$16.50).
National influenza sentinel and laboratory surveillance

expenses claimed to medical insurance f♭r treatment of

Inpatients with acute resplratOry illness. The medical expenses

revealed that influenza activlty Was Slgnificantly less than inof 2 inpatients were not calculable because the resplratOry

the previous two seasons. In early Febmary, 2000, increased

illness was complicated by underlying conditions, which

titers for hnuenza A/Beijing/262/95(H 1 ) were observed inentailed costs fわr rehabilitation over a month. The rest of thesera drawn丘om unvaccinated children in the Amakusa area.

1 7 inpatients'costs were calculated to be 73,000‑81 3,080 yen

Vaccine strains were antlgenically similar to the epidemic(mean ± SD ‑ 260,339 ±1 75,830 yen,血ys ofhospitalization:stralnS.

4‑30, median 1 1). Irthese 19 inpatients had been vaccinated,

During the observation period, a total of 233 town residents

87% (1‑0.13) (17 inpatients) might have been able to avoid(15‑101 years old, median 72) Were admitted to the town

hospitalization due to influenza followed by acute resplratOry

hospital. Ofthe 233 inpatients, 22 (66‑98 years old, medianillness･ lf so, approximately 4.4 million yen, which is 76% of78) developed respiratory illness ( 1 3 were pneumonia cases),the campalgn cost, WOuld have been saved.

Table 1. Influenza vaccine efrlCaCy ln relation to selected outcome events
Proportion of events Relative risk

Outcome s

Vaccinec vs. Non‑vaccince

Respiratory discascs hospitalization**

3/1,203 vs. 19/1,003(95% CI*)

0.13(0.04‑0.44)

Respiratory diseases death**

1/1,203 vs. 3/1,003

0.28(0.03‑2.67)

Non rcsplratOry disease hospitalization

27/2,242 vs. 91/3,326≧15 years o一d

0.44(0.29‑0.67)

Non rcsplratOry diseases hospitalization

26/I,203 vs. 68/1,003≧65 years old

0.32(0.20‑0.50)

Non rcsplratOry diseases death**

3/1,203 vs. 8/1 ,003

0.31

(0.08‑1.18)*CI: confidence interval**aII cases were at 65 years old or older

186

Table 2. 1nnuenza vaccine efficacy ln relation to influenza‑like≧13 years of age,and have assured a slngle dose for the elderly

illness (lLI)≧65 years (10)･ This new guidance should have significant

impact on the use, and thus effectiveness, of the influenza

A仕ack rate

Vaccination lLl/ Total (%)

None

Relativerisk (95% CI*)

vaccine in Japan, if the use ora slngle dose of vaccine isiZ■川u = ィru l U

widely adopted. Patients will need to pay fTor only one clinician

ヽ ‑ ヽ ー ヽl ヽ ー

5 0 2 5 7 0ノ ∠U 0

4 5 つJ 00 / / ′/ / 7 4 1 1 〇 ′h〉 l /hY

Once

′1

Twice

5 ‑一

All vaccinccs

1.90 (0.54‑6.71)

visit and one dose or vaccine, So costs will be considerably

0.46 (0.ll‑L98)

reduced. Also important for ambulatory patients will be theimpediment that two visits to the doctor now impose with

0.87 (0.27‑2.79)

regard to scheduling visits, taking time off from work (for

Vaccine cfYTICaCy (Twice vs. None): I‑0.46‑ 54 (%)*CI: confidence intctval

patients or, in some cases, children to assist parents), etc･ Thesebenefits may well lead to a much greater vacclnation coveragefor the Japanese population.

Unfbrtunately, there remains skeptlCism among the medical

DISCUSSION

profession and the public about the efficacy of vaccine protec‑

How strongly Japanese public health authorities endorsetion. This skeptlCism may be due to confusion about what,

the administration of influenza vaccine, in whom, and whether

clinically, influenza is. The common cold, "kaze", is often

to financially support these recommendations, will remaincワnfused in Japan with influenza (16)･ lt is easy for profes‑

contentious issues until data addresslng the costs and value

slOnals and the public to misunderstand the degree of protec‑

of vaccination are available and fully reviewed; the Kawaura

tion afforded by the innuenza vaccine. Efforts by public healthtown effort may assist in making these decisions. While theauthorities to provide a better understanding of the meanlng

Kawaura town data do not allow thefull evaluation of vaccineof kaze, and the elrlCaCy Ofthe influenza vaccine, to both theefficacy due to incomplete response rates and reliance on a

medical communlty and the public would undoubtedly help

simple questionnaire to judge the attack rates. However,to increase vaccine coverage of the Japanese population.

relativerisk for hospitalization and death for both resplratOry

In addition, the efforts would become increase recognlt10n

and non resplratOry illness supportsthis evidence. ln particular,that the vaccination may ameliorate the clinical severlty Of

the relativerisk for hospitalization for respiratory illness (rela‑influenza, even if it does not prevent it. Some health profes‑

tiverisk ‑ 0. 13, vaccine efncacy ‑ 87%) shows that influenza
vaccination is a very effective prevention measure.

at 50‑60%, is not high enough to support a policy ofやversal

sionals assert that the efficacy of the influenza vaccine, even

In addition to demonstratlng the level of vaccine efrlCaCy,

vaccination ( 1 7). But such an argument likely does not mclude

this study ttniquely shows the value of a community approach

the additional bene丘ts of clinically milder innuenza in someto vaccinatlOn. The Kawaura town recognized the impact thatvaccinated individuals, even if they are not fully protected

influenza had on their communlty the preceding year andagalnSt infection.

organized a communlty‑Wide effort to prevent a similar

The efIbrt in Kawaura town was broad and included

occurrence. Through these communlty efforts, an estimated
43% orthe population received vaccine, and over 90% of
these received two doses. This was a well‑organized, effective

individuals not cu汀ently recommended fわr vaccination in

Japan, e.g., school children and working adults. Prior to 1994,
the vaccine was recommended f♭r school children by the

public health campalgn.
The use of two vaccine doses, as recommended for thenational immunization law･ The policy was discontinued,

1999‑2000 season, considerably increased the cost of theness, but confusion with kaze surely contributed to this belief.

vaccination campalgn. Recent Japanese studies indicate that

The belief became widespread, and vaccination coverage

two doses of vaccine offer no additional immunogeniclty

among this group declined from about 80% in the latter 1 970s
to 1 8% in 1992 (16)･ The cPrre.nt national recommendations

however, because ofanapparent lack of evidence of effective‑

compared to a single dose (3,14). For example, Horie et al.
have found that a slngle dose oftrivalent vaccine raises thef♭r administration of vacclne lnCludes school children andreciprocal geometric mean H 1 N 1 hemagglutination titersfrom

working adults who wish to be vaccinated. Individuals in thesea prevaccination level of 61.5 to 668.4, compared to a risegroups may, however, choose to be vaccinated and those will

fTrom 85･7 to 637･7 followlng two doses in 71 working adults

not only decrease influenza morbidityin their own age groups

from 20‑60 years of age (14). Similarly, One dose of vaccine(1 8, 1 9), but also reduce mortality among older persons (20):appears to be as protective as two doses in the elderly. In athis study suggests that with efforts to vacclnate school

large study of22,462 elderly subjects living ln nurSlng homes,

children, many people are protected from influenza, leading

it was found that vaccination with one or two doses, Compared

to cost savlngS, e.g., Chil血en did not miss school, parents did

to results with nonimmunized individuals, results in 59.8%

not miss work, and medical costs were avoided. For high‑reductions in cases of influenza diagnosed by serology orrisk groups, more cost savlngS Were realized because moreculture; a 76･9% decrease in hospitalization; and a 79.1%

severe complications, due to infection Bom family and thosedecrease in death (4). Protection was similar between those

who came into contact with them were avoided.

who received one and those who received two doses. Anotherrecent study of elderly bedridden patients receivlng a Slngle

Our cost analysis did not, however, result in the Kawaura
town effort being cost effective, i.e., savlng money, Pnmarily

dose showed protection from illness, although perhaps not

because the two‑dose vaccination policy nearly doubled thehospitalization ( 1 5).

campalgn costs. If a slngle‑dose policy had been employed,

The similarityof immunogenicityand protection from one
dose of vaccine compared to two doses is reflected in theapproximately 40% of the cost would have been saved, andthe campalgn might have been cost‑effective. Secondly, theguidelines from the Japanese Ministry of Health, Labour andWelfare for the 2000‑200 1 influenza season. These guidelines

vaccine was antlgenically similar to the vims strain recovered

influenza was less active in this season, although the influenza

recommend, for the first time, that physicians use either afrom the area. Thirdly, we could not calculate the medicalslngle dose of vaccine or two doses f♭r children and adults

expenses of two lnpatients; thus, our estimation of medical

187

expenses might have been less than actually paid. ln addition,

Kiely, ∫., Ambrosch, ど., Hannoun, C., Leese, ∫., Sprenger,

clinic and pediatrics. These limitations compromised theM. J., Hampson, A. W., BroIJorgensen, K., Ahlbom, A.
M., Nokleby, H., Valle, M., 01afsson, 0･, Salmeron, F･,

cost‑effectiveness results in the Kawaura effort. A recent U.S.

Cloetta, J., Rebelo deAndrade, H., Snacken, R., Donatelli,cost analysts Of working adults, for example, has shown that

Ⅰ･, Jennipgs, L･ C･ and Strikas, R･ A･ (1997)‥ influenza

vaccinated adults report 34% fewer influenza illnesses, 42%
fewer physician visits, and 32% fTewer lost work days comparedvaccinatlOn in 22 developed countries･ Vaccine, I 5, 1 506‑

to nonvaccinated controls (2 1 ). Despite these benefits, when

8. Shindo, N. and Taniguchi, K･ (2000): Analysis of the

we did not include the medical expenses f♭r the outpatient

1511.

direct (medical care costs) and indirect (the benefits of fewer

excess death during influenza‑epidemics in Japan. Sogo

work days lost) medical costs were evaluated, the program

Rinsho, 49, 23ト237 (in Japanese).

cost US$11.17 perperson, i.e., it did not save money in this

9. Centers fわr Disease Control and Prevention (2000):Prevention and control of influenza: Recommendations

population. Nevertheless, a communlty may decide that suchan expenditure is worthwhile, and it is their responsibility toof the Advisory Committee onlmmunization Practices･

determine how they wish to spend their money. ln addition,

Morbid. Mortal. Wkly. Rep., 49 (RR3), I‑37.
10. Ministry of Health and Welfare, Japan (1998): The guide‑

the Kawaura town effort provided vaccine at 75‑90% less costthan would have been possible irthere were no communlty

lines for innuenza prevention, Announcement #247,

eBTort. This slgnificant decrease in the cost of providing vaccine

December 2 1, 1998 (in Jap.anese)･

means further savlngS Were realized among the high‑risk, i.e.

I I. National Institute of lnfectlOuS Diseases and Infectious

elderly population, whose vaccination rate remained at 55%,

Diseases Control Division, Ministry of Healthand Welfare

and that savlngS Were likely realized fわr low‑risk populations･(1998): Influenza, 1997/98 season, Japan. Infect. AgentThus, when the entire population of persons vaccinated in

SuⅣeillance Rep., 19, 272'‑273'･

Kawaura town is considered, it is likely that there were

I 2. National Institute of Infectious Diseases and Infectious

considerable cost‑savlngS With the entire program. ln addition,

Diseases Control Division, Ministry of Health and Welfare

people enjoyed better health, an intangible cost benefit that

(1999): lnnuenza, 1998/99 season, Japan. Infect. Agentis so difficult to include in cost‑effectiveness analyses.
Future efforts to ev'aluate the efrlCaCy and effectiveness ofsimilar vaccination efforts would provide invaluable assistanceto deteminlng the optlmal vaccination strategy for Japanese

SuⅣeillance Rep., 20, 289'‑290'.

1 3. Infectious Disease Surveillance Center (I 999): Innuenza
q 良 A. Announcement (in Japanese).

14. Horie, S., Sugaya, N., Mitamura, K･, Nirasawa, M･,
Takahashi, K･ and Fukazawa, T･ (1998)‥lmヮunization

citizens.

with one dose of inactivated influenza vacclne. J. Jpn.

Assoc. Infect. Dis., 72, 482‑486 (in Japanese).

ACKNOWLEDGMENTS

1 5. Fukushima, T., Nakayama, K., Monma, M., Sekizawa, K･and Sasaki, H. (1 999): Benefits of innuenza vaccination
for bedridden patients. Arch. Intern. Med., 159, 1258‑

This study was supported by the Kawaura town and theJapanese Ministry or Health, Labour and We脆re research

1259.

grant on coordination for national and prefectural surveill

16. Hirota, Y. and Kaji, M. (1994): Scepticism about influenza

lance systems (H 1 2‑Shink0‑5).

vaccine efrlCaCy in Japan. Lancet, 344, 408‑409･

17. Nakase, K., Nakashima, K., Sunagawa, T., Fujii, H.,
Ohyama, T., Takahashi, H.and Okabe, N. (2000): Evalua‑

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