Characteristics of study population
A total of 854 pregnant women were invited to participate in the survey and accepted by written consent to participate in the study (24 mothers refused to participate). Of those invited, 12 (1.4%) were excluded because they were not residents of Quito and only arrived at selected hospitals for delivery. Therefore, 842 pregnant women were included in the analysis.
The characteristics of the sample are described in Table 1. Almost three-quarters of participants in this survey were between 18 and 30 years old, 86% were mixed-race women and 58% finished high school. Most women were married or cohabited with a partner (79%), 44.2% were homemakers and approximately two thirds (65%) of women reported having at least one other child prior to this pregnancy. Nearly all women (98.7%) reported attending at least one antenatal visit and 81% reported more than four antenatal visits. Only 8% of women reported having chronic diseases.
Vaccination rate in pregnant women
The percentage of women who reported having been vaccinated against influenza at any time in their pregnancy was 36.6%. Sixty percent of women have been vaccinated during the second trimester of pregnancy. Vaccination data was confirmed with the vaccination card and/or medical records in 67% of vaccinated women (Table 1).
Table 1. Characteristics of study population in Quito, Ecuador, 2016-2017 (n = 842).
|
Characteristics
|
n (%)
|
Age
|
|
18-24
|
363 (43.1%)
|
25-30
|
260 (30.9%)
|
31-35
|
123 (14.6%)
|
≥36
|
96 (11.4)
|
Race
|
|
White
|
27 (3.4%)
|
Mixed
|
723 (85.8%)
|
Indigenous
|
54 (6.4%)
|
Black
|
30 (3.5%)
|
Other
|
8 (0.9%)
|
Education
|
|
Complete higher education or graduate degree
|
83 (9.9%)
|
Complete high school or incomplete higher
education
|
407 (48.3%)
|
Complete basic education or incomplete high
school
|
222 (26.4%)
|
Illiterate or incomplete basic education
|
130 (15.4%%)
|
Marital status
|
|
Married
|
288 (34.2%)
|
Cohabited with a partner
|
376 (44.7%)
|
Separated / Widowed / Divorced - Never Married
or Unmarried
Employment
|
178 (21.1%)
|
Public or private employee
|
175 (20.8%)
|
Independent worker
|
172 (20.4%)
|
Homemaker
|
372 (44.2%)
|
Student
|
119 (14.1%)
|
Unemployed
|
4 (0.5%)
|
Number of children (prior to this pregnancy)
|
|
_0
|
295 (35.0%)
|
_1-2
|
459 (54.5%)
|
_3-6
|
88 (10.5%)
|
Number of antenatal visits
|
|
0
|
11 (1.3%)
|
_1 to 4
|
150 (17.8%)
|
_≥5
|
681 (80.9%)
|
Gestational age at birth
|
|
24-36 weeks
|
122 (14.5%)
|
37-42 weeks
|
720 (85.5%)
|
High-risk conditions
|
|
No
|
775 (92.0%)
|
Yes
|
67 (8.0%)
|
Received influenza vaccination (self-reported)*
|
|
Yes
|
308 (36.6%)
|
Confirmed with vaccination card
|
206 (66.9%)
|
No
|
534 (63.4%)
|
Received influenza vaccination (vaccination card/medical records)**
|
|
Yes
|
206 (24.5%)
|
No
|
636 (75.5%)
|
*Vaccination reported by the women used for analysis; **Vaccination confirmed by vaccination card/medical records
Knowledge and attitudes regarding influenza and influenza vaccine
Knowledge about the severity of influenza and the existence of a vaccine was higher among women who reported having been vaccinated compared to those who reported not having been vaccinated (p = 0.017 and p < 0.001, respectively, Figure 1A and 1B). Vaccinated women perceived that the influenza vaccine is safe (95.8% vs 71.7%, respectively) and effective (68.5% vs. 61.4%, respectively) in a higher proportion than unvaccinated women (p < 0.001 y p= 0.030, respectively, Figure 1C and 1D).
Reasons for not receiving influenza vaccination
The most frequent reason identified as a barrier to vaccination among pregnant women was the lack of recommendation/offer of the vaccine by the health provider (73.9%). Other reasons in smaller proportion were lack of access (9.0%), concern with the safety of the vaccine (6.2%), not wanting/needing the vaccine (3.7%) and other causes (7.3%) (Table 2). The most common reasons for non-vaccination among women with complete basic education or higher were also related to not having received a recommendation/offer of the vaccine by the health care provider, vaccine safety concerns and other reasons, whereas for women without any educational level or with incomplete basic education, not wanting/needing the vaccine and access barriers were the most common reason for non-vaccination. (p = 0.001, Table 2).
Table 2. Main reasons for not receiving the influenza vaccine during pregnancy (n = 520), Quito, Ecuador, 2016-2017.
|
Main reason
|
|
|
|
|
All
n (%)
|
Concern about vaccine safety
n (%)
|
Do not need / do not want
n (%)
|
Access barriers
n (%)
|
Did not receive recommendation / offer
n (%)
|
Other reasons*
n (%)
|
p-
value ǂ
|
|
All
|
520 (100)**
|
32 (6.2)
|
19 (3.7)
|
47 (9.0)
|
384 (73.9)
|
38 (7.3)
|
|
Age
|
0.509
|
|
18-24
|
226 (43.5)
|
19 (59.4)
|
9 (47.4)
|
17 (36.2)
|
169 (44.0)
|
12 (31.6)
|
|
25-30
|
159 (30.6)
|
8 (25.0)
|
4 (21.1)
|
18 (38.3)
|
117 (30.5)
|
12 (31.6)
|
|
31-35
|
77 (14.8)
|
2 (6.2)
|
4 (21.0)
|
9 (19.1)
|
54 (14.1)
|
8 (21.0)
|
|
≥36
|
58 (11.1)
|
3 (9.4)
|
2 (10.5)
|
3 (6.4)
|
44 (11.4)
|
6 (15.8)
|
|
Education
|
0.001
|
|
Complete higher education
or graduate degree
|
60 (11.5)
|
2 (6.3)
|
1 (5.3)
|
3 (6.4)
|
47 (12.2)
|
7 (18.4)
|
|
Complete high school or
incomplete higher
education
|
244 (46.9)
|
16 (50.0)
|
6 (31.6)
|
21 (44.7)
|
180 (46.9)
|
21 (55.3)
|
|
Complete basic education
or incomplete high school
|
134 (25.8)
|
13 (40.6)
|
5 (26.3)
|
7 (14.9)
|
103 (26.8)
|
6 (15.8)
|
|
Illiterate or incomplete
basic education
|
82 (15.8)
|
1 (3.1)
|
7 (36.8)
|
16 (34.0)
|
54 (14.1)
|
4 (10.5)
|
|
Number of children (prior to this pregnancy)
|
0.065
|
|
None
|
188 (36.2)
|
17 (53.1)
|
4 (26.3)
|
12 (25.5)
|
146 (38.0)
|
8 (21.0)
|
|
1-2
|
285 (54.8)
|
12 (37.5)
|
12 (63.2)
|
29 (61.7)
|
208 (54.2)
|
24 (63.2)
|
|
3-6
|
47 (9.0)
|
3 (9.4)
|
2 (10.5)
|
6 (12.8)
|
30 (7.8)
|
6 (15.8)
|
|
Number of antenatal visits
|
0.621
|
|
≤4
|
117 (22.5)
|
7 (21.9)
|
6 (31.6)
|
13 (27.7)
|
85 (22.1)
|
6 (15.8)
|
|
≥ 5
|
403 (77.5)
|
25 (78.1)
|
13 (68.4)
|
34 (72.3)
|
299 (78.9)
|
32 (84.2)
|
|
High-risk conditions
|
0.615
|
|
No
|
472 (90.8)
|
28 (87.5)
|
19 (100)
|
42 (89.4)
|
349 (90.9)
|
37 (89.5)
|
|
Yes
|
48 (9.2)
|
4 (12.5)
|
0 (0)
|
5 (10.6)
|
35 (9.1)
|
4 (10.5)
|
|
|
ǂ x2 test or Fisher's test,
This table refers to the following question from the survey: “of the reasons you listed, what is the main reason you will not get a flu vaccination this flu season?
++Access barriers: “Vaccine unavailability (n = 23)”, “The health center is far from my home or opens at times that are not suitable for me (n=11), “Sick when shot was available (n = 6)”, and other reasons related to access.
*Most common other reasons were: "Don´t know”, “I had already been vaccinated before pregnancy”.
**14 people did not answer the question
Provider recommendation and offer of influenza vaccination
Among women who indicated that their health care provider recommended and offered the influenza vaccine, 82.7% reported having been vaccinated for influenza since the end of 2015. Among those who reported that their health care provider recommended but did not offer vaccination against influenza, 15.0% reported having been vaccinated for influenza. Finally, 4.3% of the respondents who did not receive either a recommendation or an influenza vaccination offer, reported having been vaccinated (p < 0.001, Figure 2).
Relationship between determinants and vaccination
A larger number of antenatal care visits, knowledge about vaccine safety, and having received recommendation (with or without offer of the vaccine) by health care personnel were associated with vaccination during pregnancy in both the bivariate and multivariate analysis (Table 3). Specifically, the vaccination rate was 1.67 times higher in women who reported having five or more antenatal controls during pregnancy than in women who reported having fewer than five controls and the association was maintained after adjustment by other predictors (adjusted PR 1.21, 95% CI 1.01-1.47). Women who perceived vaccination against influenza as safe had higher vaccination rates than those who did not (adjusted PR 1.53, 95% CI 1.03-2.37). Finally, women who reported receiving recommendation but were not offered vaccination and those who reported receiving both recommendation and were offered vaccination had 3.17 (95% CI 1.57-6.40) and 15.84 (95% CI 9.62-26.10) greater likelihood of having received the vaccine compared to women who did not receive a recommendation/offer.
Table 3. Determinants of influenza vaccination during pregnancy in Quito-Ecuador, 2016-2017.
|
Variable
|
All
|
Vaccinated n=308
|
Crude PR
|
Adjusted PR
|
|
n = 842
|
n (%)
|
CI 95%
|
CI 95%
|
Age
|
|
|
|
|
18-24
|
363
|
131 (36.1)
|
1.0
|
1.0
|
25-30
|
260
|
98 (37.7)
|
1.04 (0.85-1.29)
|
0.99 (0.86-1.15)
|
31-35
|
123
|
42 (34.2)
|
0.95 (0.71-1.25)
|
0.89 (0.72-1.11)
|
≥36
|
96
|
37 (38.5)
|
1.07 (0.80-1.42)
|
1.01 (0.84-1.22
|
Race
|
|
|
|
|
White
|
27
|
8 (29.6)
|
1.0
|
1.0
|
Afro-Ecuadorian
|
30
|
13 (43.3)
|
1.46 (0.72-2.98)
|
0.95 (0.68-1.33)
|
Mixed
|
723
|
270 (37.3)
|
1.26 (0.70-2.27)
|
0.87 (0.65-1.17)
|
Indigenous
|
54
|
15 (27.8)
|
0.94 (0.45-1.93)
|
0.74 (0.48-1.15)
|
Other
|
8
|
2 (25.0)
|
0.84 (0.22-3.20)
|
0.60 (0.22-1.64)
|
Education
|
|
|
|
|
Complete higher education or graduate degree
|
83
|
23 (27.1)
|
1.0
|
1.0
|
Complete secondary education or incomplete
higher education
|
407
|
157 (38.6)
|
1.39 (0.96-2.01)
|
1.27 (0.99-1.64)
|
Basic education complete or incomplete high
school
|
222
|
82 (36.9)
|
1.33 (0.90-1.96)
|
1.30 (0.99-1.71)
|
Illiterate or incomplete basic education
|
130
|
46 (35.4)
|
1.28 (0.84-1.94)
|
1.39 (0.90-1.84)
|
Marital status
|
|
|
|
|
Married
|
288
|
107 (37.2)
|
1.0
|
1.0
|
Cohabited with a partner
|
376
|
144 (38.3)
|
1.03 (0.84-1.26)
|
0.99 (0.87-1.13)
|
Separated / Widowed / Divorced - Never
Married or Unmarried
|
178
|
57 (32.0)
|
0.86 (0.66-1.12)
|
0.95 (0.77-1.17)
|
Employment
|
|
|
|
|
Housewife
|
172
|
58 (33.7)
|
1.0
|
1.0
|
Student
|
119
|
38 (31.9)
|
1.16 (0.91-1.47)
|
1.00 (0.86-1.17)
|
Unemployed
|
4
|
1 (25.0)
|
0.97 (0.72-1.29)
|
0.95 (0.77-1.17)
|
Public or private employee
|
175
|
61 (34.9)
|
0.92 (0.66-1.28)
|
0.88 (0.69-1.12)
|
Independent worker
|
372
|
150 (40.3)
|
0.72 (0.13-3.97)
|
0.82 (0.44-1.52)
|
Number of children
|
|
|
|
|
0
|
88
|
37 (42.1)
|
1.0
|
1.0
|
1-2
|
459
|
169 (36.8)
|
1.06 (0.87-1.30)
|
0.90 (0.79-1.03)
|
3-6
|
295
|
102 (34.6)
|
1.22 (0.91-1.63)
|
1.03 (0.81-1.32)
|
Antenatal Care
|
|
|
|
|
≤4
|
161
|
38 (23.6)
|
1.0
|
1.0
|
≥ 5
|
681
|
270 (39.7)
|
1.67 (1.25-2.25)†
|
1.21 (1.01-1.47)†
|
Gestational age at birth
|
|
|
|
|
<37 weeks
|
122
|
37 (30.3)
|
1.0
|
1.0
|
≥37 weeks
|
720
|
271 (37.6)
|
1.24 (0.93-1.65)
|
1.08 (0.91-1.28)
|
High-risk conditions
|
|
|
|
|
No
|
775
|
290 (37.4)
|
1.0
|
1.0
|
Yes
|
67
|
18 (26.9)
|
0.72 (0.48-1.08)
|
0.91 (0.69-1.20)
|
Distance to health center (minutes)
|
|
|
|
|
>30 minutes
|
35
|
9 (25.7)
|
1.0
|
1.0
|
15-30 minutes
|
102
|
35 (34.3)
|
1.33 (0.71-2.49)
|
0.75 (0.54-1.05)
|
0-15 minutes
|
696
|
262 (37.6)
|
1.46 (0.83-2.59)
|
0.79 (0.57-1.08)
|
Knowledge regarding influenza vaccine
|
|
|
|
|
No
|
54
|
25 46.3)
|
1.0
|
1.0
|
Yes
|
721
|
268 (37.2)
|
0.80 (0.59-1.09)
|
0.91 (0.73-1.12)
|
Do not know/no answer
|
67
|
15 (22.4)
|
0.48 (0.28-0.82)
|
0.90 (0.63-1.28)
|
Knowledge about the transmission of the disease
|
|
|
|
|
No
|
87
|
34 (39.1)
|
1.0
|
1.0
|
Yes
|
666
|
251 (37.7)
|
0.96 (0.73-1.28)
|
1.10 (0.91-1.32)
|
Do not know/no answer
|
89
|
23 (25.8)
|
0.66 (0.43-1.03)
|
1.23 (0.93-1.63)
|
Knowledge about the existence of vaccine
|
|
|
|
|
No
|
17
|
3 (17.7)
|
1.0
|
1.0
|
Yes
|
767
|
301 (39.2)
|
2.22 (0.79-6.24)
|
0.69 (0.25-1.91)
|
Do not know/no answer
|
58
|
4 (6.9)
|
0.39 (0.10-1.58)
|
0.55 (0.17-1.82)
|
Perception about vaccine safety
|
|
|
|
|
No
|
32
|
6 (18.8)
|
1.0
|
1.0
|
Yes
|
678
|
295 (43.5)
|
2.32 (1.12-4.80)†
|
1.53 (1.03-2.37)†
|
Do not know/no answer
|
132
|
7 (5.3)
|
0.28 (0.10-0.78)
|
0.65 (0.33-1.28)
|
Perception about vaccine effectiveness
|
|
|
|
|
No
|
72
|
29 (40.2)
|
1.0
|
1.0
|
Yes
|
539
|
211 (39.2)
|
0.97 (0.72-1.31)
|
0.87 (0.61-1.2)
|
Do not know/no answer
|
231
|
68 (29.4)
|
0.73 (0.52-1.03)
|
0.86 (0.68-1.09)
|
Recommendation and offer of vaccine
|
|
|
|
|
No recommendation/non-offer
|
397
|
17 (4.3)
|
1.0
|
1.0
|
Recommendation / non-offer
|
80
|
12 (15.0)
|
3.50 (1.74-7.05)†
|
3.17 (1.57-6.40)†
|
Recommendation / offer
|
336
|
278 (82.7)
|
19.32 (12.1-30.85)†
|
15.84 (9.62-26.10)†
|
|
|
|
|
|
|
† p-value < 0.05.
CI: Confidence interval; PR: Prevalence Ratio