Characteristics of the travelers
Of 9,746 registered clients, 46 with missing values were excluded, leaving 9,700 (see Supplemental Table 3 in Additional file 1). The overall median age was 32 [21–45] years; 880 (9.1%) and 549 (5.7%) clients were aged 0–15 and ≥ 65 years, respectively (Table 1). The duration of travel was known in 9,190 (94.7%) clients, and the most common was ≥ 181 days (35.8%), with a higher percentage of younger than elderly clients, who tended to travel for ≤ 2 weeks. The most common reason for travel overall was business (3,930, 40.5%), accompanying their family members (66.8%) in the less-than-16-year-old group, and sightseeing (65.6%) in the elderly (> 65 years) group (Table 1). By country, the US (1,118 [11.5%]) was the most common destination, followed by Brazil (1,001 [10.3%]), while Asia was the most common continent with 4,008 (41.3%) clients.
Table 1
Characteristics of participants by age group
|
All
|
Age 0 to 15 years
|
Age 16 to 64 years
|
Age 65 years or over
|
Number of clients
|
9700
|
880
|
8271
|
549
|
Male (%)
|
5806 (59.9)
|
436 (49.5)
|
5042 (61)
|
328 (59.7)
|
Female (%)
|
3894 (40.1)
|
444 (50.5)
|
3229 (39)
|
221 (40.3)
|
Age, median, years [IQR]
|
32 [21,45]
|
6 [3, 11]
|
32 [23,43]
|
69 [67,72]
|
Days from first consultation to travel, median, days [IQR]
|
33 [17,60]
|
50 [25,96]
|
32 [16,57]
|
35 [20,60]
|
Immunization record (%)
|
4876 (50.3)
|
666 (75.7)
|
4113 (49.7)
|
97 (17.7)
|
Request for vaccine (%)
|
7793 (80.3)
|
657 (74.7)
|
6726 (81.3)
|
410 (74.7)
|
Travel period (%)
|
|
|
|
|
less than 7 days
|
675 (7.3)
|
14 (1.7)
|
622 (7.9)
|
39 (7.3)
|
7–13 days
|
2272 (24.7)
|
75 (9.1)
|
1936 (24.7)
|
261 (48.8)
|
14–27 days
|
1468 (16)
|
55 (6.6)
|
1270 (16.2)
|
143 (26.7)
|
28–55 days
|
811 (8.8)
|
35 (4.2)
|
732 (9.4)
|
44 (8.2)
|
56–181 days
|
674 (7.3)
|
29 (3.5)
|
616 (7.9)
|
29 (5.4)
|
more than 181 days
|
3290 (35.8)
|
620 (74.9)
|
2651 (33.9)
|
19 (3.6)
|
Travel purpose (%)
|
|
|
|
|
Group tourism
|
640 (6.6)
|
26 (3.0)
|
413 (5.0)
|
201 (36.6)
|
Individual tourism
|
1910 (19.7)
|
70 (8.0)
|
1681 (20.3)
|
159 (29.0)
|
Business
|
3930 (40.5)
|
10 (1.1)
|
3790 (45.8)
|
130 (23.7)
|
Moving with family
|
1198 (12.4)
|
588 (66.8)
|
602 (7.3)
|
8 (1.5)
|
Migration
|
26 (0.3)
|
7 (0.8)
|
17 (0.2)
|
2 (0.4)
|
Study
|
1330 (13.7)
|
127 (14.4)
|
1201 (14.5)
|
2 (0.4)
|
Volunteer work
|
472 (4.9)
|
14 (1.6)
|
441 (5.3)
|
17 (3.1)
|
Visiting friends/relatives
|
132 (1.4)
|
42 (4.8)
|
76 (0.9)
|
14 (2.6)
|
Others
|
214 (2.2)
|
15 (1.7)
|
167 (2.0)
|
32 (5.8)
|
Most visited countries (%)
|
|
|
|
|
First
|
USA 1118 (11.5)
|
USA 173 (19.7)
|
USA 916 (11.1)
|
Brazil 114 (20.8)
|
Second
|
Brazil 1001 (10.3)
|
China 101 (11.5)
|
Brazil 812 (9.8)
|
Kenya 85 (15.5)
|
Third
|
China 769 (7.9)
|
Brazil 75 (8.5)
|
China 662 (8.0)
|
Tanzania 53 (9.7)
|
Fourth
|
Kenya 750 (7.7)
|
Thailand 70 (8.0)
|
India 647 (7.8)
|
South Africa 49 (8.9)
|
Fifth
|
India 696 (7.2)
|
Indonesia 41 (4.7)
|
Kenya 647 (7.8)
|
Peru 39 (7.1)
|
Visit more than one country (%)
|
1666 (17.2)
|
20 (2.3)
|
1471 (17.8)
|
175 (31.9)
|
Visit low or lower-middle income countries included (%)
|
5067 (52.2)
|
252 (28.6)
|
4502 (54.4)
|
313 (57)
|
IQR, interquartile range; USA, United States of America |
Except for the YFV, the most common vaccines requested were against hepatitis A, rabies, tetanus, and hepatitis B (Table 2). Vaccines were required in 7,793 clients (80.3%). Those traveling outside Asia, Africa, and Latin America, had more requests for vaccines against measles, rubella, meningococcal, and Tdap than those planning to travel to these regions. YFV was requested and planned by 3,014 and 3,559 (36.7%) clients, respectively. The proportion of YFV requests in those aged ≥ 65 years was higher (52.3%) than in those aged < 16 years (14.4%) and 16–64 years (31.4%). Altitude sickness and malaria prophylaxes were most requested by travelers into Latin America (77.2%) and Africa (72.4%) (Table 2).
Table 2
Differences between the interventions that the participants wanted to use and the interventions they actually used after the travel consultation
|
Vaccines and prescriptions that the participants themselves wanted
|
Vaccines and prescriptions actually given after pre-travel consultation
|
*Percentage
difference
|
**Change ratio
|
***p value
|
Hepatitis A vaccine
|
3946
|
5655
|
17.6
|
1.43
|
< 0.001
|
Hepatitis B vaccine
|
2562
|
2961
|
4.1
|
1.16
|
< 0.001
|
Rabies vaccine
|
2804
|
3209
|
4.2
|
1.14
|
< 0.001
|
Vaccines containing tetanus toxoid
|
3017
|
4625
|
16.6
|
1.53
|
< 0.001
|
Tdap
|
151
|
597
|
4.6
|
3.95
|
< 0.001
|
DTaP
|
471
|
2388
|
19.8
|
5.07
|
< 0.001
|
Typhoid fever vaccine
|
1513
|
2468
|
9.8
|
1.63
|
< 0.001
|
Japanese encephalitis vaccine
|
1231
|
1745
|
5.3
|
1.42
|
< 0.001
|
Meningococcal ACWY vaccine
|
463
|
772
|
3.2
|
1.67
|
< 0.001
|
Meningococcal B vaccine
|
8
|
32
|
0.2
|
4.00
|
< 0.001
|
Vaccines containing measles
|
772
|
2012
|
12.8
|
2.61
|
< 0.001
|
Vaccines containing rubella
|
682
|
2006
|
13.6
|
2.94
|
< 0.001
|
Yellow fever vaccine
|
3014
|
3559
|
5.6
|
1.18
|
< 0.001
|
Prophylaxis for acute altitude sickness
|
338
|
370
|
0.3
|
1.09
|
< 0.05
|
Prophylaxis for malaria
|
1146
|
1252
|
1.12
|
1.10
|
< 0.001
|
*Percentage difference: percentage after pretravel consultation minus that before pretravel consultation (after - before).
**Change ratio: Ratio of the number of cases after pretravel consultation to that before pretravel consultation (after/ before).
***Compared by McNemar test
|
Interventions
Following the PTC, the median number of and most common vaccines planned were 3 (IQR, 1–4) per person, and HAV, followed by tetanus-containing vaccine, respectively. Several travelers to Asia were vaccinated against hepatitis A, hepatitis B, rabies, and typhoid (see Supplementary Table 4 in Additional file 1). Of 29,082 planned vaccines, 24.5% were unapproved in Japan. Of the unapproved vaccines, the most frequently vaccinated were adjuvant-containing hepatitis A, typhoid fever, and rabies vaccines.
Overall, the number of planned vaccines after PTC increased compared to the required vaccines before PTC, especially for vaccines containing measles and rubella, and diphtheria, Tetanus, Pertussis (Table 2 and Supplementary Table 4 in Additional file 1). The number of planned meningococcal vaccine recipients was small, but with a remarkable increase after consultation (Table 2). The numbers of rabies, hepatitis B, yellow fever, and Japanese encephalitis vaccines were generally similar between the planned and requested numbers. The YFV number of consultations was higher among ≥ 65-year-olds than the < 65-year-olds (60.1% vs. 35.3%, p < 0.001). The percentage of prescriptions for altitude sickness prophylaxis did not change significantly after the consultation. For malaria prophylaxis, there was a slight increase in those planning travels to Africa, and conversely, a decrease in those traveling to other regions.
Malaria prophylaxis or emergency standby treatment was recommended in 22.5% (2,180/9,700) of clients, and in 34.8% (1,821/5,226) of those traveling for < 56 days; and especially in those who planned to travel to the African region (68.8%, 1,429/2,078). Among those traveling for < 56 days, there were two clients each with unknown prescription status and planned emergency standby treatment; beside these, only 60.8% of those recommended for malaria prophylaxis actually received the prescriptions. The most common destination countries for which malaria prophylaxis was prescribed were Kenya, Tanzania, Uganda, and Ghana. However, even in countries with high malaria risk (over 10 confirmed cases per 1,000 populations), the prescription rate for those who received prophylaxis recommendations varied from 42.1–84.2% (see Supplementary Table 5 in Additional file 1).
The most common advice was for rabies post-exposure prophylaxis (PEP), mosquito repellent use, and dietary precautions; all of which were common among travelers to Asia and Africa (Table 3).
Table 3
Advice given during consultations by region of travel
|
All
|
Asia
|
Africa
|
South America
|
Others
|
Multi
|
N (%)
|
9700
|
4008
|
2593
|
1809
|
1660
|
1670
|
Explanation of post-exposure prophylaxis for rabies
|
6436 (66.4)
|
3115 (77.7)
|
1784 (68.8)
|
1207 (66.7)
|
597 (36)
|
1097 (65.7)
|
How to use mosquito repellents
|
6486 (66.9)
|
2841 (70.9)
|
2092 (80.7)
|
1394 (77.1)
|
457 (27.5)
|
1248 (74.7)
|
Explanation of the risk of leptospirosis and/or schistosomiasis due to freshwater exposure
|
2901 (29.9)
|
1514 (37.8)
|
740 (28.5)
|
454 (25.1)
|
314 (18.9)
|
476 (28.5)
|
Explanation of dietary habits to avoid foodborne diseases
|
5780 (59.6)
|
2842 (70.9)
|
1592 (61.4)
|
1071 (59.2)
|
507 (30.5)
|
998 (59.8)
|
Avoiding traffic accidents
|
3286 (33.9)
|
1817 (45.3)
|
626 (24.1)
|
440 (24.3)
|
501 (30.2)
|
482 (28.9)
|
Preventive actions for acute mountain sickness
|
768 (7.9)
|
304 (7.6)
|
121 (4.7)
|
256 (14.2)
|
134 (8.1)
|
185 (11.1)
|
Discussing the risks and prevention of sexually transmitted diseases
|
809 (8.3)
|
321 (8)
|
280 (10.8)
|
179 (9.9)
|
85 (5.1)
|
198 (11.9)
|
Taking overseas travel accident insurance
|
3359 (34.6)
|
1436 (35.8)
|
954 (36.8)
|
640 (35.4)
|
456 (27.5)
|
596 (35.7)
|
Others
|
116 (1.2)
|
64 (1.6)
|
18 (0.7)
|
13 (0.7)
|
26 (1.6)
|
11 (0.7)
|
Quality indicators
GNI category, the percentage of hepatitis A vaccination (HAV) planning and dietary advice to prevent foodborne diseases (Fig. 1)
These vaccines and advice were weakly correlated with each of the GNI categories respectively (ρ = 0.37, p < 0.01; ρ = 0.41, p < 0.01). These vaccines and advice tended to be considered when people were traveling to lower or upper-middle income countries. Compared to the advice on HAV, there was a greater difference in advice about eating and drinking among facilities.
Risk category of rabies, the percentage of pre-exposure prophylaxis (PrEP) planning, and explaining post-exposure prophylaxis (PEP) (Fig. 2)
As rabies incidence rate increased, the percentage of explaining PEP increased for those that planned to travel to high-risk rabies countries (ρ = 0.30, p < 0.01). However, the percentage of explaining PEP was quite low in some facilities, as with the other advice. Furthermore, the rate of PrEP planning was not related to the incidence rate (p > 0.05). There was a tendency for the implementation rate to decrease in most facilities in countries with a slightly high risk of human rabies (0.6–1.5 deaths per 100,000 population), including African countries (such as Kenya and Tanzania) with relatively large numbers of visitors from Japan.
Risk category of typhoid fever and the percentage of typhoid fever vaccination planning (Fig. 3)
The percentage of typhoid fever vaccine planning and advice both tended to increase in proportion to the incidence of typhoid fever (ρ = 0.41, p < 0.01). Since typhoid vaccine is an unapproved vaccine in Japan, the vaccine planning rate was lower in facilities that do not handle unapproved vaccines.
Recommendations for prevention of mosquito-borne diseases and implementation of mosquito control advice (Fig. 4)
For P. falciparum malaria, the higher the incidence in the destination country, the higher the rate of preventive medication prescription plans (ρ = 0.66, p < 0.001). The percentage of advice on mosquito repellant use was non-significantly higher for those traveling to high-risk countries according to the dengue fever risk category (p > 0.05).
Catch-up vaccination rate of measles-containing vaccines to the clients (with and without vaccination records) by age (Fig. 5)
For those without an immunization record, many facilities tended to immunize more clients in their 30s and 40s, with less natural immunity and who are likely to have been immunized once (Fig. 2A and B). For those with a record, the catch-up immunization rate was relatively high among those in their teens to their 50s. However, regardless of vaccination history, there was a strong inter-institutional variation in measles-containing vaccine coverage (Fig. 2C).