Disruptions to routine childhood vaccinations in low- and middle-income countries during the COVID-19 pandemic: A systematic review

Determinants of undervaccination of routine childhood immunization in Argentina: A cross-sectional study

Routine childhood immunization is one of the most effective methods of preventing infectious diseases in children. In Argentina, there has been a decline in routine immunization coverage since 2015, with very little evidence to date on underlying drivers of this steady decline. We administered an online nationwide behavioral insights survey in Argentina between July 1-25, 2022, targeting parents with at least one child under the age of 12 years. Our survey included 1504 parents, 7% (n = 111) of whom did not or only partially vaccinated their children. We found that, compared to the youngest parents (aged 18-24), older parents were less likely to under-vaccinate their children (e.g., 30-34 year-old parents: adjusted Odds Ratio (aOR): 0.31, 95% Confidence Interval (CI) 0.16-0.57). Parents who undervaccinated their children were more likely to take vaccination advice from parent and wellness social media influencers (parent influencers: aOR 2.51, 95% CI 1.46-4.31), and were less likely to trust the social media accounts of official health organizations (aOR 0.82, 95% CI 0.70-0.96). Furthermore, these parents had heightened concerns about routine immunizations, including the number of vaccines given to children and potential for adverse side effects. When asked whether they knew enough to make a vaccine decision for their children, parents who undervaccinated their children were more likely to report that they did not know enough about vaccines or the vaccination schedule to make a decision. These results offer important insights into parental concerns surrounding routine childhood immunization and suggest potential drivers of - and solutions to - the decline in routine immunization seen in Argentina since 2015.

COVID-19 related disruption and resilience in immunisation activities in LMICs: a rapid review

OBJECTIVES

We conducted a rapid review to determine the extent that immunisation services in low-income and middle-income countries (LMICs) were disrupted by the COVID-19 pandemic and synthesised the factors that can be used to build resilience in future.

DESIGN

Rapid review reported in accordance with the Preferred reporting for Systematic reviews and Meta-Analyses (PRISMA) guidelines.

DATA SOURCES

PubMed and Web of Science were searched through 6 October 2023.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

We included studies that focused on disruption to immunisation activities due to the COVID-19 pandemic in LMICs. Outcomes included routine vaccine coverage, supplementary immunisation activities, vaccine doses, timing of vaccination, supply chain changes, and factors contributing to disruption or resilience.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers used standardised methods to search, screen and code studies. Quality assessment was performed using a modified version of the Critical Appraisal Skills Programme for qualitative research. Findings were summarised qualitatively.

RESULTS

Of 4978 identified studies, 85 met the eligibility criteria. Included studies showed declines in immunisation activities across LMICs related to the COVID-19 pandemic. These included reductions in achieved routine coverage, cancellation or postponement of campaigns and underimmunised cohorts. Immunisation was most disrupted in the early months of the pandemic; however, recovery varied by country, age-group and vaccine. Though many countries observed partial recovery in 2020, disruption in many countries continued into 2021. It has also been noted that clinician staff shortages and vaccine stock-outs caused by supply chain disruptions contributed to immunisation delays, but that concern over COVID-19 transmission was a leading factor. Key resiliency factors included community outreach and healthcare worker support.

CONCLUSIONS

There is limited information on whether reductions in vaccination coverage or delays have persisted beyond 2021. Further research is needed to assess ongoing disruptions and identify missed vaccine cohorts.

Impact of the COVID-19 Pandemic on Measles Vaccination Coverage and Estimated Catch-Up Efforts for Serbia

BACKGROUND

Measles is highly infectious, requiring ≥95% vaccine coverage rate (VCR) to prevent outbreaks. This study aimed to understand the impact of the COVID-19 pandemic on routine measles-containing vaccine (MCV) VCRs in Serbia and estimate national and regional catch-up vaccination required to prevent outbreaks.

METHODS

A multiplier model was used to calculate annual MCV dose 1 (MCV1) and MCV dose 2 (MCV2) VCRs for children 1-6 and 6-12 years of age, respectively, for 2011-2022. Postpandemic (2023-2024) VCRs were modeled. The numbers of administered doses were compared to prepandemic and postpandemic, and monthly catch-up rates were calculated for 12-, 18- and 24-month campaigns.

RESULTS

Between prepandemic and pandemic periods, national MCV1 VCR decreased from 88% to 81%, while MCV2 VCR decreased from 92% to 89%, corresponding to 20,856 missed MCV1 and 8760 missed MCV2 doses. Assuming national VCRs returned to prepandemic levels post-2022, 18% of children 1-6 years of age and 11% of children 6-12 years of age would have missed their MCV1 and MCV2 doses, respectively, by 2024. To catch up missed doses under this scenario, most regions would require monthly catch-up rates of 25%, 16% or 12% for MCV1 and 14%, 9% or 7% for MCV2, considering 12-, 18- or 24-month campaigns, respectively.

CONCLUSIONS

The pandemic negatively impacted MCV VCRs in Serbia, leaving a sizeable proportion of children with missed doses. Significant catch-up efforts are required to recover VCRs to prepandemic levels and avoid future measles outbreaks, with increased monthly administration rates versus those in prepandemic periods.

Trust in health workers and patient-centeredness of care were strongest factors associated with vaccination for Kenyan children born between 2017-2022

Objective

Although vaccination confidence is declining globally, there is little detailed information from low- and middle-income countries about factors influencing routine vaccination behavior in these contexts.

Methods

In mid-2022, we surveyed people who gave birth in Kenya between 2017-2022, and asked them about their children's vaccination history and about hypothesized correlates of vaccination per the Behavioural and Social Drivers of Vaccination model.

Results

Of 873 children in this sample, 117 (13%) were under-vaccinated (i.e., delayed or missing vaccine dose(s)) - and under-vaccination was more common among births during the COVID-19 pandemic (2020-2022) versus pre-pandemic (2017-2019). In multi-level multivariable models, children of respondents who expressed concerns about serious side effects from vaccines had significantly higher odds of missed vaccine dose(s) (aOR 2.06, 95 % CI 1.14-3.72), and there was a strong association between having more safety concerns now versus before the COVID-19 pandemic (aOR missed dose(s) 4.44, 95 % CI 1.71-11.51; aOR under-vaccination 3.03, 95 % CI 1.28-7.19). People with greater trust in health workers had lower odds of having a child with missed vaccine dose(s) (aOR 0.85, 95 % CI 0.75-0.97). People who reported higher patient-centered quality of vaccination care had much lower odds of having children with delayed or missed vaccine dose(s) (aOR missed dose(s) 0.14, 95 % CI 0.04-0.58; aOR under-vaccination 0.27, 95 % CI 0.10-0.79).

Conclusions

These findings highlight potential strategies to improve vaccine coverage: greater focus on patient-centered quality of care, training healthcare workers on how to address safety concerns about vaccines, and building trust in the health care system and in health workers.

Clinical Picture and Risk Factors for Poor Outcome in Streptococcus pneumoniae Meningitis of Childhood on Three Continents

BACKGROUND

Streptococcus pneumoniae meningitis (SpM) remains a major health burden worldwide, particularly in low- and middle-income countries. Identifying the patients at highest risk for mortality and disabling sequelae may reveal potentially avoidable predisposing factors and identify patients most in need of intensive care. We searched for factors that do not require laboratory facilities.

METHODS

This study was a secondary analysis of prospectively collected data from 5 clinical trials of childhood bacterial meningitis on 3 continents between 1984 and 2017. SpM cases were analyzed by study site and predictors for poor outcome (death or severe sequelae) were identified from the whole series, Latin America and Angola.

RESULTS

Among a total of 1575 children (age range: 2 months to 15 years), 505 cases were due to pneumococci. Compared to other etiologies, SpM doubled the death rate (33% vs. 17%) and tripled poor outcome (15% vs. 6%). In SpM, Glasgow Coma Score <13 [odds ratio (OR): 4.73] and previous antibiotics in Angola (OR: 1.70) were independent predictors for death. Predictors for poor outcome were age <1 year (OR: 2.41) and Glasgow Coma Score <13 (OR: 6.39) in the whole series, seizures in Latin America (OR: 3.98) and previous antibiotics in Angola (OR: 1.91). Angolan children had a 17-fold increased risk for poor outcome when compared with Finnish children ( P = 0.011).

CONCLUSIONS

Our study proved the severity of SpM when compared with other etiologies. The outcome was especially poor in Angola. Most patients at risk for poor outcome are easily identified by clinical factors on admission.

The Impact of the Coronavirus Pandemic on Vaccination Coverage in Latin America and the Caribbean

BACKGROUND

Routine vaccination coverage in Latin America and the Caribbean declined prior to and during the coronavirus pandemic. We assessed the pandemic's impact on national coverage levels and analyzed whether financial and inequality indicators, immunization policies, and pandemic policies were associated with changes in national and regional coverage levels.

METHODOLOGY

We compared first- and third-dose coverage of diphtheria-pertussis-tetanus-containing vaccine (DTPcv) with predicted coverages using time series forecast modeling for 39 LAC countries and territories. Data were from the PAHO/WHO/UNICEF Joint Reporting Form. A secondary analysis of factors hypothesized to affect coverages during the pandemic was also performed.

RESULTS

In total, 31 of 39 countries and territories (79%) had greater-than-predicted declines in DTPcv1 and DTPcv3 coverage during the pandemic, with 9 and 12 of these, respectively, falling outside the 95% confidence interval. Within-country income inequality (i.e., Gini coefficient) was associated with significant declines in DTPcv1 coverage, and cross-country income inequality was associated with declines in DTPcv1 and DTPcv3 coverages. Observed absolute and relative inequality gaps in DTPcv1 and DTPcv3 coverage between extreme country quintiles of income inequality (i.e., Q1 vs. Q5) were accentuated in 2021, as compared with the 2019 observed and 2021 predicted values. We also observed a trend between school closures and greater-than-predicted declines in DTPcv3 coverage that approached statistical significance (p = 0.06).

CONCLUSION

The pandemic exposed vaccination inequities in LAC and significantly impacted coverage levels in many countries. New strategies are needed to reattain high coverage levels.

Measles Vaccine Coverage and Disease Outbreaks: A Systematic Review of the Early Impact of COVID-19 in Low and Lower-Middle Income Countries

Objectives: We aimed to evaluate changes to measles-containing vaccine (MCV) provision and subsequent measles disease cases in low- and lower-middle income countries (LICs, LMICs) in relation to the COVID-19 pandemic. Methods: A systematic search was conducted of MEDLINE, OVID EMBASE and PubMed records. Primary quantitative and qualitative research studies published from January 2020 were included if they reported on COVID-19 impact on MCV provision and/or measles outbreak rates within LICs and LMICs. Results: 45 studies were included. The change in MCV1 vaccination coverage in national and international regions ranged -13% to +44.4% from pre-COVID time periods. In local regions, the median MCV1 and overall EPI rate changed by -23.3% and -28.5% respectively. Median MCV2 rate was disproportionally impacted in local areas during COVID-interruption time-periods (-48.2%) with ongoing disruption in early-recovery time-periods (-17.7%). 8.9% of studies reported on vaccination status of confirmed measles cases; from these, 71%-91% had received no MCV dose. Conclusion: MCV vaccination coverage experienced ongoing disruption during the recovery periods after initial COVID-19 disruption. Vaccination in local area datasets notably experienced longer-term disruption compared to nationally reported figures.

Estimating the health effects of COVID-19-related immunisation disruptions in 112 countries during 2020-30: a modelling study

BACKGROUND

There have been declines in global immunisation coverage due to the COVID-19 pandemic. Recovery has begun but is geographically variable. This disruption has led to under-immunised cohorts and interrupted progress in reducing vaccine-preventable disease burden. There have, so far, been few studies of the effects of coverage disruption on vaccine effects. We aimed to quantify the effects of vaccine-coverage disruption on routine and campaign immunisation services, identify cohorts and regions that could particularly benefit from catch-up activities, and establish if losses in effect could be recovered.

METHODS

For this modelling study, we used modelling groups from the Vaccine Impact Modelling Consortium from 112 low-income and middle-income countries to estimate vaccine effect for 14 pathogens. One set of modelling estimates used vaccine-coverage data from 1937 to 2021 for a subset of vaccine-preventable, outbreak-prone or priority diseases (ie, measles, rubella, hepatitis B, human papillomavirus [HPV], meningitis A, and yellow fever) to examine mitigation measures, hereafter referred to as recovery runs. The second set of estimates were conducted with vaccine-coverage data from 1937 to 2020, used to calculate effect ratios (ie, the burden averted per dose) for all 14 included vaccines and diseases, hereafter referred to as full runs. Both runs were modelled from Jan 1, 2000, to Dec 31, 2100. Countries were included if they were in the Gavi, the Vaccine Alliance portfolio; had notable burden; or had notable strategic vaccination activities. These countries represented the majority of global vaccine-preventable disease burden. Vaccine coverage was informed by historical estimates from WHO-UNICEF Estimates of National Immunization Coverage and the immunisation repository of WHO for data up to and including 2021. From 2022 onwards, we estimated coverage on the basis of guidance about campaign frequency, non-linear assumptions about the recovery of routine immunisation to pre-disruption magnitude, and 2030 endpoints informed by the WHO Immunization Agenda 2030 aims and expert consultation. We examined three main scenarios: no disruption, baseline recovery, and baseline recovery and catch-up.

FINDINGS

We estimated that disruption to measles, rubella, HPV, hepatitis B, meningitis A, and yellow fever vaccination could lead to 49 119 additional deaths (95% credible interval [CrI] 17 248-134 941) during calendar years 2020-30, largely due to measles. For years of vaccination 2020-30 for all 14 pathogens, disruption could lead to a 2·66% (95% CrI 2·52-2·81) reduction in long-term effect from 37 378 194 deaths averted (34 450 249-40 241 202) to 36 410 559 deaths averted (33 515 397-39 241 799). We estimated that catch-up activities could avert 78·9% (40·4-151·4) of excess deaths between calendar years 2023 and 2030 (ie, 18 900 [7037-60 223] of 25 356 [9859-75 073]).

INTERPRETATION

Our results highlight the importance of the timing of catch-up activities, considering estimated burden to improve vaccine coverage in affected cohorts. We estimated that mitigation measures for measles and yellow fever were particularly effective at reducing excess burden in the short term. Additionally, the high long-term effect of HPV vaccine as an important cervical-cancer prevention tool warrants continued immunisation efforts after disruption.

FUNDING

The Vaccine Impact Modelling Consortium, funded by Gavi, the Vaccine Alliance and the Bill & Melinda Gates Foundation.

TRANSLATIONS

For the Arabic, Chinese, French, Portguese and Spanish translations of the abstract see Supplementary Materials section.

Impact of COVID-19 Pandemic on Routine Childhood Immunization Programs in Indonesia: Taking Rural and Urban Area into Account

Background

To date, the primary global concern has revolved around addressing the COVID-19 pandemic. However, there is a growing awareness of the pandemic's secondary impacts on critical aspects of healthcare, such as childhood immunization programs.

Objective

This study aims to assess the impact of the COVID-19 pandemic on childhood immunization programs in Indonesia, with a specific focus on performance disparities between rural and urban areas. It considers factors like access, utilization, and program workload.

Methods

Data were collected from primary health cares (PHCs) in two regions in West Java Province, Indonesia, representing rural and urban areas. A descriptive analysis was conducted to compare vaccination coverage, drop-out rates, and the ratio of vaccinators per dose from 2019 to 2021 in 40 and 22 PHCs for rural and urban areas, respectively. A general linear model was employed to evaluate the differences in these parameters over the three consecutive years.

Results

The results indicate fluctuations in vaccine coverage over the three years, with the most significant impact observed in 2020, particularly in rural areas. Statistical analysis revealed a significant difference in routine immunization coverage, drop-out rates, and vaccinator ratios between rural and urban areas from 2019 to 2021 (p<0.05). In 2021, both rural and urban areas displayed significant differences in performance parameters for routine immunization and COVID-19 vaccination (p<0.05), except in terms of coverage for IPV and COVID-19 vaccination.

Conclusion

The study highlights a reduction in routine immunization coverage during the pandemic, a concerning issue that increases the risk of vaccine-preventable diseases, particularly in rural areas.

Vaccination Utilization and Subnational Inequities during the COVID-19 Pandemic: An Interrupted Time-Series Analysis of Administrative Data across 12 Low- and Middle-Income Countries

BACKGROUND

During and after the SARS-CoV-2 (COVID-19) pandemic, many countries experienced declines in immunization that have not fully recovered to pre-pandemic levels. This study uses routine health facility immunization data to estimate variability between and within countries in post-pandemic immunization service recovery for BCG, DPT1, and DPT3.

METHODS

After adjusting for data reporting completeness and outliers, interrupted time series regression was used to estimate the expected immunization service volume for each subnational unit, using an interruption point of March 2020. We assessed and compared the percent deviation of observed immunizations from the expected service volume for March 2020 between and within countries.

RESULTS

Six countries experienced significant service volume declines for at least one vaccine as of October 2022. The shortfall in BCG service volume was ~6% (95% CI -1.2%, -9.8%) in Guinea and ~19% (95% CI -16%, 22%) in Liberia. Significant cumulative shortfalls in DPT1 service volume are observed in Afghanistan (-4%, 95% CI -1%, -7%), Ghana (-3%, 95% CI -1%, -5%), Haiti (-7%, 95% CI -1%, -12%), and Kenya (-3%, 95% CI -1%, -4%). Afghanistan has the highest percentage of subnational units reporting a shortfall of 5% or higher in DPT1 service volume (85% in 2021 Q1 and 79% in 2020 Q4), followed by Bangladesh (2020 Q1, 83%), Haiti (80% in 2020 Q2), and Ghana (2022 Q2, 75%). All subnational units in Bangladesh experienced a 5% or higher shortfall in DPT3 service volume in the second quarter of 2020. In Haiti, 80% of the subnational units experienced a 5% or higher reduction in DPT3 service volume in the second quarter of 2020 and the third quarter of 2022.

CONCLUSIONS

At least one region in every country has a significantly lower-than-expected post-pandemic cumulative volume for at least one of the three vaccines. Subnational monitoring of immunization service volumes using disaggregated routine health facility information data should be conducted routinely to target the limited vaccination resources to subnational units with the highest inequities.

Reasons for reductions in routine childhood immunisation uptake during the COVID-19 pandemic in low- and middle-income countries: A systematic review

The coronavirus disease 2019 (COVID-19) pandemic has resulted in a substantial decline in routine immunisation coverage in children globally, especially in low- and middle-income countries (LMICs). This study summarises the reasons for disruptions to routine child immunisations in LMICs. A systematic review (PROSPERO CRD42021286386) was conducted following PRISMA 2020 guidelines. Six databases were searched: MEDLINE, Embase, Global Health, CINAHL, Scopus and MedRxiv, on 11/02/2022. Observational and qualitative studies published from January 2020 onwards were included if exploring reasons for missed immunisations during the COVID-19 pandemic in LMICs. Study appraisal used National Heart, Lung, and Blood Institute and Critical Appraisal Skills Programme tools. Reasons for disruption were defined with descriptive codes; cross-sectional (quantitative) data were summarised as mean percentages of responses weighted by study population, and qualitative data were summarised narratively. A total of thirteen studies were included describing reasons behind disruptions; 7 cross-sectional (quantitative), 5 qualitative and 1 mixed methods. Seventeen reasons for disruptions were identified. In quantitative studies (total respondents = 2,853), the most common reasons identified were fear of COVID-19 and consequential avoidance of health centres (41.2%, SD ±13.3%), followed by transport challenges preventing both families and healthcare professionals from reaching vaccination services (11.1% SD ±16.6%). Most reasons stemmed from reduced healthcare-seeking (83.4%), as opposed to healthcare-delivery issues (15.2%). Qualitative studies showed a more even balance of healthcare-seeking (49.5%) and healthcare-delivery issues (50.5%), with fear of COVID-19 remaining a major identified issue (total respondents = 92). The most common reasons for disruption were parental fear of COVID-19 and avoidance of health services. Health systems must therefore prioritise public health messaging to encourage vaccine uptake and recovery of missed immunisations.