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Nonattendance at vaccination appointments is a big challenge for health workers as it is difficult to track routine vaccination schedules. In Ethiopia, 3 out of 10 children have incomplete vaccination and the timely receipt of the recommended vaccines is low. Thus, innovative strategies are required to reach the last mile where mobile technology can be effectively utilized to achieve better compliance. Despite this promising technology, little is known about the role of text message–based mobile health interventions in improving the complete and timely receipt of routine childhood vaccinations in Ethiopia.
This trial aimed to determine the effect of mobile phone text message reminders on the completion and timely receipt of routine childhood vaccinations in northwest Ethiopia.
A two-arm, parallel, superiority randomized controlled trial was conducted in 9 health facilities in northwest Ethiopia. A sample size of 434 mother-infant pairs was considered in this trial. Randomization was applied in selected health facilities during enrollment with a 1:1 allocation ratio by using sealed and opaque envelopes. Participants assigned to the intervention group received mobile phone text message reminders one day before the scheduled vaccination visits. Owing to the nature of the intervention, blinding of participants was not possible. Primary outcomes of full and timely completion of vaccinations were measured objectively at 12 months. A two-sample test of proportion and log-binomial regression analyses were used to compare the outcomes between the study groups. A modified intention-to-treat analysis approach was applied and a one-tailed test was reported, considering the superiority design of the trial.
A total of 426 participants were included for the analysis. We found that a higher proportion of infants in the intervention group received Penta-3 (204/213, 95.8% vs 185/213, 86.9%, respectively;
Mobile phone text message reminders significantly improved complete and timely receipt of all recommended vaccines. Besides, they had a significant effect in improving the timely receipt of specific vaccines. Thus, text message reminders can be used to supplement the routine immunization program in resource-limited settings. Considering different contexts, studies on the implementation challenges of mobile health interventions are recommended.
Pan African Clinical Trial Registry PACTR201901533237287; https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=5839
Vaccine-preventable diseases (VPDs) remain a common cause of childhood mortality with an estimated 3 million deaths globally each year. Vaccines have proven to be one of the most effective preventive interventions and they provide successful means for controlling VPDs [
Despite the tremendous efforts to improve immunization programs, vaccination coverage and timeliness have remained suboptimal [
In Ethiopia, routine childhood vaccines are administered at birth, fourth week, sixth week, tenth week, and ninth month before 1 year of age [
Maintaining reductions in mortality due to VPDs relies upon continued vaccination uptake that is reliant on subsequent attendance for each vaccination appointment. However, the frequently mentioned reasons for missed and delayed vaccination in children are related to the difficulty in tracking the vaccination appointments as scheduled [
Different studies have shown that text message reminders are promising in improving attendance at health facilities and health outcomes [
In Ethiopia, mobile phone technology access is expanding rapidly [
This study applied a two-arm, parallel, superiority, individually randomized controlled trial design with a 1:1 allocation ratio. This trial followed a published study protocol that details the methods and approaches implemented in the trial [
For this particular study, eligible mother-infant pairs from the University of Gondar Comprehensive Specialized Hospital and all the 8 health centers were included. The eligibility criteria for the study participant selection are shown in
Mothers who have an infant who took the Bacillus Calmette-Guérin vaccination up to 4 weeks of age
For twin infants presented for vaccination, the younger infant was included
Mothers aged 18 years and older
Mothers who had a working mobile phone
Resided in the study area at least for 6 months (permanent residents)
Mothers who were willing to provide consent for participation in the study
Infants who already received vaccinations other than Bacillus Calmette-Guérin or polio zero vaccines
Mothers who could not read mobile phone text messages in Amharic or English languages
Mothers who had no mobile network access in their house/compound
Mothers who planned to relocate out of the study area during the study follow-up period
During enrollment, when more than one eligible mother-infant pair from the same house/compound presented to the health facility for vaccination, only one infant (younger) was included to reduce the risk of information pollution among study participants. The recruitment of the study participants started on May 1, 2019 and ended on June 26, 2019. Study participants were followed up for 12 months.
Participants assigned to the intervention group received the routine vaccination appointment reminder and additional mobile phone text message reminders one day before the scheduled vaccination visits on the sixth week, tenth week, fourteenth week, and ninth month after childbirth. Participants in the usual care group used vaccination cards and were informed of the due date of the next vaccination schedule verbally by health care providers working in health facilities during the facility visit. For the intervention group, a computerized text message reminder system was designed and developed for this particular study considering the local context by the eHealthLab Ethiopia research team [
Full vaccination coverage and on-time full vaccination coverage were the primary outcomes for this trial. The secondary outcomes included coverage and timeliness for specific vaccine doses. In this trial, an infant was defined as having achieved full (complete) vaccination once he/she had received all the recommended vaccines included in the national immunization schedule, namely, a dose of Bacillus Calmette-Guérin, 3 doses of oral polio vaccine, 3 doses each of pentavalent and pneumococcal conjugate vaccine, 1 dose of inactivated polio vaccine, 2 doses of rotavirus vaccine, and 1 dose of measles vaccine by the age of 12 months [
The effect of mobile phone text message reminders was measured by comparing the difference in the vaccination coverage and timely receipt of vaccination between the intervention and usual care groups at 6 weeks, 10 weeks, 14 weeks, 9 months, and 12 months of age.
Before the commencement of the randomized controlled trial, a baseline assessment was conducted in the study area to obtain recent estimates on the complete and timely vaccination status of children [
The sample size calculation for full vaccination assumed a power of 90%, a significance level (α) of 5% for superiority design, a difference of 15% between the intervention and usual care groups from the baseline full vaccination coverage of 64.3% [
A sample size of 434 mother-infant pairs (217 in each of the intervention and usual care groups) was required to detect a difference of 15% between the intervention and usual care groups from the baseline on-time full vaccination coverage of 31.9% [
The units of randomization were mother-infant pairs randomized in one of the two study arms. All mother-infant pairs who were eligible and gave informed written consent for participation were randomly assigned to either of the study groups by using a simple randomization technique. Randomization was applied in the selected health facilities during enrollment with a 1:1 allocation ratio by using sealed and opaque envelopes within each health facility separately.
To prevent foreknowledge of intervention assignment, we used identical and small-sized sealed opaque envelopes for the random sequence generation. Random sequence generation was ensured by a research assistant ahead of the study subject’s enrollment with which study arms were marked on paper and folded to fit the envelope. Finally, the sealed envelopes prepared for both the intervention and usual care groups were combined for each health facility and shuffled so that the allocation sequence remained concealed. When the mother-infant pairs were found to be eligible for the trial, they were assigned to the intervention or usual care group by randomly picking up a closed envelope.
Owing to the nature of the intervention, blinding of the study participants was not possible. Health workers who administered the vaccines and recorded the vaccination status of the infants were blinded to study group allocations. Outcome assessors were also blinded to the intervention allocation.
This trial was implemented as per the a priori published protocol [
The baseline data collected from the study participants and the outcome data collected from EPI registers were entered into the EpiData version 3.1 software (EpiData Association). Finally, the data were exported to the STATA statistical software for analysis. Analyses were done with the modified intention-to-treat analysis principle at the participant level so that all randomized participants with available outcome data were included for the analysis, regardless of the degree of exposure to study intervention [
This study obtained ethical approval from the University of Gondar Institutional Ethical Review Board Reference O/V/P/RCS/05/060/2018. The purpose and procedures of the trial were explained to all the study participants. Accordingly, informed written consent was sought from all the study participants during enrollment. Confidentiality and anonymity of the information obtained were maintained at all levels of data handling. Before the commencement of the study, permission was obtained from all the required administrative levels, including the Amhara Public Health Institute and Ethio telecom.
Between May 1, 2019 and June 26, 2019, 515 mother-infant pairs were assessed for eligibility. Accordingly, 434 eligible mother-infant pairs were enrolled, with 81 excluded for not meeting the eligibility criteria (
The CONSORT flow diagram of study participant enrollment, randomization, allocation, and analysis for the trial in Gondar city, northwest Ethiopia in 2020 (N=426). mITT: modified intention-to-treat.
The baseline characteristics of both the study groups are shown in
Baseline characteristics of the study participants enrolled in the trial in Gondar city, northwest Ethiopia in 2020 (N=426).
Characteristics | Intervention group (n=213), n (%) | Usual care group (n=213), n (%) | ||
|
.42 | |||
|
≤24 | 64 (30.1) | 71 (33.3) |
|
|
25-34 | 123 (57.7) | 110 (51.7) |
|
|
≥35 | 26 (12.2) | 32 (15.1) |
|
|
.86 | |||
|
Currently married | 195 (91.5) | 194 (91.1) |
|
|
Currently not married | 18 (8.5) | 19 (8.9) |
|
|
.44 | |||
|
Orthodox | 180 (84.5) | 181 (84.9) |
|
|
Muslim | 28 (13.1) | 23 (10.8) |
|
|
Others | 5 (2.4) | 9 (4.3) |
|
|
.55 | |||
|
No formal education | 18 (8.4) | 23 (10.8) |
|
|
Primary | 65 (30.5) | 70 (32.9) |
|
|
Secondary and above | 130 (61.1) | 120 (56.3) |
|
|
.12 | |||
|
Housewife | 105 (49.3) | 100 (46.9) |
|
|
Employed | 48 (22.5) | 33 (15.5) |
|
|
Merchant | 38 (17.9) | 49 (23.0) |
|
|
Others | 22 (10.3) | 31 (14.6) |
|
|
.77 | |||
|
Female | 107 (50.2) | 110 (51.6) |
|
|
Male | 106 (49.8) | 103 (48.4) |
|
|
.16 | |||
|
First | 81 (38.1) | 95 (44.6) |
|
|
Second or later | 132 (61.9) | 118 (55.4) |
|
|
.53 | |||
|
Rural | 14 (6.6) | 11 (5.2) |
|
|
Urban | 199 (93.4) | 202 (94.8) |
|
|
.30 | |||
|
Poor | 67 (31.5) | 75 (35.2) |
|
|
Middle | 79 (37.0) | 64 (30.1) |
|
|
Rich | 67 (31.5) | 74 (34.7) |
|
|
.31 | |||
|
<5 members | 143 (67.1) | 133 (62.4) |
|
|
≥5 members | 70 (32.9) | 80 (37.6) |
|
|
.40 | |||
|
<15 minutes | 96 (45.1) | 109 (51.2) |
|
|
15-30 minutes | 82 (38.5) | 70 (32.9) |
|
|
>30 minutes | 35 (16.4) | 34 (15.9) |
|
|
.22 | |||
|
≤2 years | 37 (17.4) | 47 (22.1) |
|
|
>2 years | 176 (82.6) | 166 (77.9) |
|
|
.24 | |||
|
Regular/standard | 97 (45.5) | 109 (51.2) |
|
|
Smart | 116 (54.5) | 104 (48.8) |
|
In this trial, the proportion of infants who completed the 12-month vaccination series in the intervention group was significantly higher than that of infants who completed the 12-month vaccination series in the usual care group (176/213, 82.6% vs 151/213, 70.9%, respectively; one-tailed
Effect of mobile phone text message reminders on full and timely completion of vaccination among infants in Gondar city, northwest Ethiopia in 2020 (N=426).
Vaccination status | Intervention group (n=213),vn (%) | Usual care group (n=213), n (%) | Absolute difference (%) (95% lower CI)a | |
Full vaccination | 176 (82.6) | 151 (70.9) | 11.7 (5.1) | .002 |
On-time full vaccination | 135 (63.3) | 85 (39.9) | 23.4 (15.7) | <.001 |
aOne-tailed test reported for superiority design and there is no upper bound to the absolute difference.
bOne-tailed test
The pentavalent and measles vaccination coverages were used to measure the specific vaccination coverage for the vaccine doses administered at the age of sixth week, tenth week, fourteenth week, and ninth month vaccination schedules. At the fourteenth week, Penta-3 coverage in the intervention group was significantly higher than that in the usual care group (204/213, 95.8% vs 185/213, 86.9%, respectively; one-tailed
Effect of mobile phone text message reminders on receipt of specific vaccines in Gondar city, northwest Ethiopia in 2020 (N=426).
Vaccination | Intervention group (n=213), n (%) | Usual care group (n=213), n (%) | Absolute difference (95% lower CI)a | |
Penta-1 | 210 (98.6) | 203 (95.3) | 3.3 (0.6) | .02 |
Penta-2 | 209 (98.1) | 193 (90.6) | 7.5 (3.9) | <.001 |
Penta-3 | 204 (95.8) | 185 (86.9) | 8.9 (4.5) | <.001 |
Measles | 195 (91.5) | 169 (79.3) | 12.2 (6.7) | <.001 |
aOne-tailed test reported for superiority design and there is no upper bound to the absolute difference.
bOne-tailed test
The trial showed that a significantly higher proportion of infants in the intervention group received Penta-3 vaccination on time as compared to infants in the usual care group (181/204, 88.7% vs 128/185, 69.2%, respectively; one-tailed
Effect of mobile phone text message reminders on timely receipt of specific vaccines in Gondar city, northwest Ethiopia in 2020.
Vaccinationa | Intervention group, n (%) | Usual care group, n (%) | Absolute difference (95% lower CI)b | |
Penta-1 | 193 (91.9) | 164 (80.8) | 11.1 (5.6) | <.001 |
Penta-2 | 189 (90.4) | 149 (77.2) | 13.2 (7.3) | <.001 |
Penta-3 | 181 (88.7) | 128 (69.2) | 19.5 (12.9) | <.001 |
Measles | 170 (87.1) | 116 (68.6) | 18.5 (11.5) | <.001 |
aTimeliness for the specific vaccines was calculated from vaccinated infants in both study groups. The total number of vaccinated infants for each vaccine is shown in
bOne-tailed test reported for superiority design and there is no upper bound to the absolute difference.
cOne-tailed test
Log-binomial regression analysis was performed to determine the effect of mobile phone text message reminders on the primary outcomes of full and timely completion of vaccination. Mothers in the intervention group were 17% more likely to fully vaccinate their infants as compared to mothers in the usual care group (RR 1.17, 95% lower CI 1.07). In addition, mothers in the intervention group were 59% more likely to timely complete all doses of vaccines for their infants as compared to mothers in the usual care group (RR 1.59, 95% lower CI 1.35) (
Log-binomial regression analysis of the effect of mobile phone text message reminders on the primary outcomes in Gondar city, northwest Ethiopia in 2020 (N=426).
Vaccination status | Intervention group (n=213), n (%) | Usual care group (n=213), n (%) | Risk ratio (95% lower CI)a |
Full vaccination | 176 (82.6) | 151 (70.9) | 1.17 (1.07) |
On-time full vaccination | 135 (63.3) | 85 (39.9) | 1.59 (1.35) |
aOne-tailed test reported for superiority design and there is no upper bound to the risk ratio.
In this trial, subgroup analysis was performed to assess the effect of the mobile phone text message reminders within categories of subgroups of the sociodemographic characteristics and to evaluate for statistically significant subgroup differences. The interaction tests showed that there were no significant effect differences across the subgroups of the included sociodemographic variables, except for the household wealth index. With the interaction test, the effect differences across the subgroups of household wealth index were statistically significant (
Subgroup analysis of the effect of mobile phone text message reminders on timely completion of vaccination in Gondar city, northwest Ethiopia in 2020.
Characteristics | Intervention group (n=135), n (%) | Usual care group (n=85), n (%) | Stratum-specific risk ratio (95% lower CI)a | ||
|
.46 | ||||
|
≤24 years | 46 (71.9) | 29 (40.8) | 1.76 (1.35) |
|
|
>25 years | 89 (59.7) | 56 (39.4) | 1.51 (1.24) |
|
|
.13 | ||||
|
Below secondary | 44 (53.1) | 25 (26.9) | 1.97 (1.42) |
|
|
Secondary and above | 91 (70.0) | 60 (50.0) | 1.40 (1.17) |
|
|
.01 | ||||
|
Poor | 32 (47.8) | 33 (44) | 1.09 (0.81) |
|
|
Middle or rich | 103 (70.6) | 52 (37.7) | 1.87 (1.53) |
|
|
.46 | ||||
|
<5 members | 89 (62.2) | 55 (41.4) | 1.51 (1.23) |
|
|
≥5 members | 46 (65.7) | 30 (37.5) | 1.75 (1.33) |
|
|
.61 | ||||
|
<15 minutes | 63 (65.6) | 47 (43.1) | 1.52 (1.22) |
|
|
≥15 minutes | 72 (61.5) | 38 (36.5) | 1.68 (1.32) |
|
|
.39 | ||||
|
Regular/standard | 55 (56.7) | 43 (39.4) | 1.44 (1.13) |
|
|
Smart | 80 (68.9) | 42 (40.4) | 1.71 (1.37) |
|
aOne-tailed test reported for superiority design and there is no upper bound to the risk ratio.
b
For the 213 mothers in the intervention group, 852 mobile phone text messages were dispatched successfully from the automated system for the subsequent 4 vaccination appointments. In addition, the actual delivery status of the text message to the participants was confirmed by Ethio telecom. Out of the automatically sent 852 mobile phone text messages, 764 (89.7%) were delivered successfully to the study participants. Among the 213 participants, 176 (82.6%), 11 (5.2%), 10 (4.7%), and 7 (3.3%) received 4, 3, 2, and 1 text message reminder, respectively (
Mobile phone text message delivery status in the intervention group (n=213).
For this particular trial, post hoc study power was calculated using STATA 14 software. Taking into account the superiority design of the trial, the power to detect the observed difference was 89.4% for full vaccination and 99.8% for on-time full vaccination.
This trial assessed the role of implementing a locally developed mobile phone text message reminder system to improve the immunization program in the Ethiopian context. The findings of our study indicated that text message reminders have a positive significant effect on the timely completion of routine vaccinations. This study also showed that text message reminders significantly improved timely vaccination uptake in the sixth week, tenth week, fourteenth week, and ninth month after childbirth for specific vaccines. In the intervention, of the automatically sent 852 text messages, 764 (89.7%) were delivered successfully to the study participants. This trial showed that a significantly higher proportion of infants in the intervention group were fully vaccinated as compared to infants in the usual care group (one-tailed
In this trial, infants from the intervention group had higher vaccination coverage for specific vaccines as compared to the infants from the usual care group. This finding is in line with that of other studies conducted in Zimbabwe [
In this study, we also observed that mobile phone text message reminders have a statistically significant effect on the timely completion of childhood vaccinations (one-tailed
In the subgroup analysis, this study showed that the intervention had positive effects on the subgroups of the sociodemographic characteristics of the study participants. This means that the intervention package appears to be beneficial for almost all mothers in the intervention group, implying that the proposed intervention has the potential to improve timely vaccination in the larger community. Besides, in the subgroup analysis, household wealth index was identified as a significant effect modifier with which mothers from middle or rich households were more benefited from the text message reminder intervention. This study also pointed out that using text message reminders is not without difficulties that need to be addressed. This was evidenced by findings of other studies that reported similar barriers [
Our results add unique findings to the body of literature on the impact of mobile phone text message reminders on timely vaccination, which has not been studied so far in the Ethiopian context. Our findings indicated that mobile phone–based text message reminders can be added to the arsenal of other interventions as a supplement to existing immunization programs. Moreover, the results of this study could help in guiding the future adoption and implementation of mHealth interventions in low-income countries such as Ethiopia. Program managers could consider using this system to improve child immunization service uptake as the mobile phone–based reminder system for this trial was designed in Ethiopia with the local context. This study was limited to only those mothers who have mobile phones. In implementing a text messaging reminder system, the needs of those mothers who have no mobile phones need to be addressed. Mobile phone ownership may also increase as mobile services and mobile phones become increasingly ubiquitous in low-income countries. The digital health literacy of the end users might also influence the effective implementation of mHealth interventions in different contexts, which demand prior assessment in future trials. To scale up the mobile phone–based text message interventions in the national EPI of a resource-constrained setting, further studies that guide large-scale implementation are recommended.
This study has the following strengths. In this trial, the study participants were allocated randomly, which resulted in balanced demographic characteristics between the study groups. This study also applied allocation concealment during the enrollment of the study participants. In addition, objective measures were used for ascertaining the vaccination status as an outcome and outcome assessors were also blind to the intervention.
Our study had the following limitations. We enrolled mothers who owned a mobile phone and presented for infant vaccination in health facilities of Gondar city, which may limit the generalizability of our findings to the general population. Owing to the nature of this study, blinding of study participants was not possible. Further, the possibility of information contamination among the participants across the study groups cannot be ruled out. The automated mobile phone text message reminder system was not set to provide information on whether mothers had received and read the text message reminders or not. Hence, the reading status of the text message reminders was confirmed at the end of the study via phone calls, which might have a possibility of recall bias.
In conclusion, mobile phone text message reminders significantly improved complete and timely receipt of all recommended childhood vaccinations in the study setting. Moreover, text message reminders had a significant effect in improving timely receipt of specific vaccines provided in the sixth week, tenth week, fourteenth week, and ninth month after childbirth. Thus, text message reminders can be an additional tool to usual care for improving timely completion of childhood vaccinations in resource-limited settings. Locally developed mobile phone text message reminders as a new evolution may contribute to strengthening the routine immunization program and should be considered by policy makers and program managers to improve timely completion of vaccinations. Further rigorous interventional studies in different contexts with more focus on implementation challenges of mHealth interventions are recommended.
Client registration, client list, vaccination appointment scheduling, and vaccination reminder analysis pages of the automated reminder system.
Mobile text message reminder contents and reminder message sending process.
CONSORT-eHEALTH checklist (V 1.6.1).
expanded program on immunization
mobile health
risk ratio
vaccine-preventable disease
The authors would like to thank the University of Gondar, Doris Dukes Charitable Foundation project, and the German Academic Exchange Service (DAAD) program for supporting this trial. The authors are also grateful to the Amhara Public Health Institute, Gondar City Health Department, Ethio telecom, and all the study participants. This study was financially supported by the Doris Dukes Charitable Foundation project with the award number 2017187. The funder had no role in the design, data collection, analysis, and interpretation of the study findings. The data on which these findings were developed are available upon reasonable request.
ZAM, KAG, MW, and BT conceptualized and initiated the trial. All the authors were involved in the design and implementation of this trial. The original draft was produced by ZAM and reviewed by all authors. All authors read and approved the final manuscript.
None declared.