Effectiveness of Catch-Up Vaccinations after COVID-19 Containment - China, 2020

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.

Routine pediatric vaccinations during the COVID-19 pandemic: A review of the global impact

The coronavirus disease 2019 (COVID-19) pandemic has put standard, routine childhood vaccinations at risk worldwide. The disruption in vaccine coverage has resulted in a negative impact on the health of children, with some races, ethnicities, age groups, areas of settlement, and parts of the world affected more than others. This literature review studied and examined the impact of COVID-19 on infant, child, and adolescent vaccinations. Retrospectively, the analysis showed a decline, delays, or interruptions in the coverage of vaccines during the pan-demic and a decline in some countries' pre-pandemic and post-pandemic eras. Necessary attempts and efforts should be made for these delayed and missed vaccinations, as failure to do so could put children's health at risk. Thus, priority should be directed at instituting catch-up programs to support vaccine uptake and decrease the probability of acquiring vaccine-preventable diseases.

Transmission Pattern of Measles Virus Circulating in China During 1993-2021: Genotyping Evidence Supports That China Is Approaching Measles Elimination

BACKGROUND

To provide useful insights into measles elimination progress in China, measles surveillance data were reviewed, and the transmission patterns of measles viruses circulating in China during 1993-2021 were analyzed.

METHODS

Measles incidence data from the National Notifiable Disease Reporting System of the China Center for Disease Control and Prevention were analyzed. A total of 17 570 strains were obtained from 30 of 31 provinces in mainland China during 1993-2021. The recommended genotyping window was amplified. Genotyping analysis was conducted for comparison with the reference strains. Phylogenetic analyses were performed to identify genetic relationships among different lineages within the genotypes.

RESULTS

With high coverage of routine immunization and intensive supplementary immunization activities, measles incidence has shown a downward trend since 1993, despite 2 resurgences, reaching a historic low level in 2020-2021 (average 0.5 per million). During 1993-2021, 9 genotypes including domestic genotype H1; imported genotypes B3, D4, D8, D9, D11, G3, and H2; and vaccine-associated genotype A were identified. Among them, the genotype H1 strain circulated endemically in China for more than 25 years; the last strain was detected in Yunnan Province in September 2019. Multiple imported genotypes have been identified since 2009 showing different transmission patterns. Since April 2020, no imported strains have been detected, while vaccine-associated genotype A continues to be detected.

CONCLUSIONS

The evidence of low incidence during 2020-2021 and virological surveillance data in this study confirm that China is currently approaching measles elimination.

Catch-up vaccination campaign in children between 6 and 8 years old during COVID-19 pandemic: The experience in a COVID hub in Milan, Italy

BACKGROUND

COVID-19 has led to disruption in routine immunization programs around the world. Effective strategies need to be developed to address the decline in vaccine coverage to avoid preventable disease outbreaks. Our study reports a 4-days campaign for the catching-up of missed vaccinations in children aged between 6 and 8 years, in Milan, Italy.

METHODS

The catch-up vaccination campaign (21st-24th of September 2021) involved children born in 2013, 2014 and 2015. These cohorts, if not already immunized, received the fourth dose of the Diphtheria-Tetanus-acellular Pertussis and Poliomyelitis vaccination (DTaPP4), the second dose of the Measles-Mumps and Rubella vaccination (MMR2) and Chickenpox, according to the Italian vaccine schedule.

RESULTS

3,943 letters were sent to children with a missing vaccination. 1,315 children, 33% of expected, were vaccinated during the campaign. The 2015 cohort was the one that benefited most from the initiative, 955 children were vaccinated for a total of 1,864 doses administered. This has led to a significant increase of 20.0 percentage points (p.p.) in vaccination coverages for the fourth dose of DTaPP and the second dose of MMR. 214 children for the 2014 cohort and 146 for the 2013 cohort were vaccinated during the following days, these cohorts have been already called previously therefore the participation in the campaign and consequently the increase in vaccination coverages were less substantial.

CONCLUSIONS

This experience has demonstrated that a mass vaccination campaign could be a useful tool in catch-up strategies, even during the pandemic. It should be part of a bigger immunization program strategy that also includes efforts to simultaneously strengthen routine immunization services. With the appropriate organizational improvements, this initiative could pave the way for future successful campaigns involving different age groups and vaccinations.

Burden of whooping cough in China (PertussisChina): study protocol of a prospective, population-based case-control study

INTRODUCTION

Pertussis is one of the top 10 diseases of children under 10 years of age, and the few vaccine-preventable diseases who is on a rise in China in recent years; however, the true burden of pertussis, including age-stratified incidence and risk factors of severe sequelae, are under-recognised. We aim to estimate the health burden of laboratory-confirmed pertussis by age groups, considering the setting of illness onset (ie, in community, outpatient and inpatient), in a Chinese population (~2.23 million in total) at two sites.

METHODS AND ANALYSIS

This paper describes the study design of a 1-year, prospective, age-stratified and population-based case-control study, including site selection, study population, case registry, ascertainment and enrolment, control recruitment, follow-up of case, microbiological methods, data collection, quality control activities and statistical methods used to generate incidence estimates. During June 2021 through May 2022, registry of suspected pertussis cases (namely chronic/persistent cough) will be conducted in several participating hospitals (SHs) at the two sites, which are selected based on Healthcare Utilisation and Attitudes Surveys (HUAS) carried out before study initiation. A case-control study will be conducted in the SHs and we aim to enrol a total of 1000 suspected pertussis cases (ie, all hospital admissions and the first 1-3 outpatient visits each week each hospital) and 2000 frequency matched healthy controls in community. Our primary study outcome, the laboratory-confirmed Bordetella pertussis infection, will be determined by a comprehensive laboratory methods and procedures (ie, culture, PCR and serological tests) in both cases and controls at enrolment and during 60-day's follow-up visits. Finally, data from HUAS (ie, population size), case registry (ie, the total number of suspected pertussis cases) and case-control study (ie, the prevalence or population attributable fraction of Bordetella pertussis) will be combined to calculate incidence and its 95% CI through bootstrap method. Epidemiological analyses will be conducted to determine the risk factors associated with severe sequelae of pertussis.

ETHICS AND DISSEMINATION

This study has been approved by Chinese Centre for Disease Control and Prevention's Institutional Review Board (no. ICDC-202110). Results will be disseminated via academic presentations and publication in peer-reviewed journals, and will provide valuable scientific data and some new insights into the incidence, aetiology and risk factors for severe sequelae of pertussis to academic societies and the public health authorities who is currently struggling and fighting against this burdensome disease worldwide.

Impact of COVID-19 pandemic on routine vaccination coverage of children and adolescents: A systematic review

BACKGROUND AND AIMS

Scientists and healthcare workers have expressed their concerns on the impacts of the COVID-19 pandemic on vaccination coverage in children and adolescents. Therefore, we aimed to systematically review the studies addressing this issue worldwide.

METHODS

We conducted a systematic search of relevant studies using the keywords on databases of PubMed, Web of Science, and Cochrane on May 22, 2021. The identified records were imported into EndNote software and underwent a two-phase screening process consisting of title/abstract and full-text screenings against inclusion criteria. The data of the included studies were summarized into a table and the findings were analyzed in a systematic approach.

RESULTS

From 26 eligible studies, 21 studies demonstrated decreased vaccination rates in the children during the COVID-19 pandemic, while three studies found increased or no significant changes only in influenza vaccination. The two remaining studies from Brazil and Sweden also showed no significant changes in vaccination rates in the children during the pandemic.

CONCLUSION

Most of the reports worldwide reported a decline or delay in vaccination at the time of the COVID-19 pandemic. A sustained catch-up program seems to be necessary, especially in low-income countries, to avoid any vaccine dose missing. Facilitating the vaccination process is recommended, such as decreasing the waiting time for vaccination at the health center, addressing the fear and concerns related to COVID infection for parents, and enhancing vaccine availability, and promoting access in remote areas. Countries should ensure proper vaccination to prevent future pandemics related to vaccine-preventable diseases.