Mass Immunization Campaign Research Articles

Analysis of Beyfortus® (Nirsevimab) Immunization Campaign: Effectiveness, Biases, and ADE Risks in RSV Prevention.

Respiratory infections with respiratory syncytial virus (RSV) account for an important part of hospital admissions for acute respiratory infections. Nirsevimab has been developed to reduce the hospital burden of RSV infections. Compared with the product previously used, it has a stronger binding capacity to RSV F protein and a high affinity for FcRn (neonatal receptor for the Fc fragment of IgG), which extends its lifespan. Nirsevimab has been shown to be highly effective in reducing hospitalization rates of RSV infections but a large or unknown number of treated subjects have been excluded in clinical and post-marketing studies. However, analysis of these studies cannot exclude that, in rare cases, nirsevimab facilitates and worsens RSV infection (or other respiratory infections). This could be attributable to antibody-dependent enhancement (ADE) which has been observed with RSV F protein antibodies in inactivated vaccine trials. This risk has been incompletely assessed in pre-clinical and clinical trials (incomplete exploration of nirsevimab effector functions and pharmacokinetics). ADE by disruption of the immune system (not studied and due to FcRn binding) could explain why there is no reduction in all-cause hospital admissions in treated age groups. Given the high price of nirsevimab, the cost-effectiveness of mass immunization campaigns may therefore be debated from an economic as well as a scientific point of view.

Routine community-based vitamin A supplementation compared to the Mass campaign among 6-59-months old’s children in two health districts, Far North Cameroon

Introduction: Vitamin A supplementation (VAS) is one of the most cost-effective interventions with the greatest impact in reducing child mortality. Mass campaigns are costly, donor-driven, and heavily dependent on funding for mass immunization campaigns. We analyzed routine community-based VAS (rVAS) coverage using the pilot approach of strengthening community participation versus the mass campaign strategy during the “Mother and Child Health and Nutrition Action Week” (MCHNAW). Methods: This was a descriptive study among from children under five prospectively followed up in a VAS program in Kaele and Guidiguis health districts. We performed a descriptive analysis of data from routine VAS program after capacity building of Community Health Workers (CHW) and compared them with data from the MCHNAW in the period October 2019 and May 2020. Data were collected in the health facilities from the registers to ODK Kobocollect and analyzed by Microsoft Excel 2010. Results: rVAS showed 95.29% (92.49% Kaele; 98.49% Guidiguis) coverage for children aged 6-11 months (first dose). And 98.29% (97.71% Kaele & 98.77% Guidiguis) coverage for children aged 12-59 months (2nd dose). In comparison, VAS coverage in the mass campaign was lower with 68.46% (61.80% Kaele 72.42% Guidiguis) for 6-11 months and 62.57% (61.27% Kaele & 63.28% Guidiguis) for 12-59 months. These coverages are also lower, compared to the national target coverage (80%). rVAS showed high coverage (>92%) compared to Mass campaign and national target among 6–59-months age children in both health district in the far North Cameroon. However, this study has not analyzed the cost of both strategies of VAS. Conclusion: Reinforce the routine community-based VAS showed the best coverage to reach children under-five compared to the mass campaign VAS. However, there is need more cost-effectiveness studies to confirm whether strengthening community-based VAS could be a better practice versus mass campaign.

Perceptions of yellow fever emergency mass vaccinations among vulnerable groups in Uganda: A qualitative study.

Yellow fever (YF), a mosquito-borne viral hemorrhagic fever, is endemic in Uganda and causes frequent outbreaks. A total of 1.6 million people were vaccinated during emergency mass immunization campaigns in 2011 and 2016. This study explored local perceptions of YF emergency mass immunization among vulnerable groups to inform future vaccination campaigns. In this qualitative study, we conducted 43 semi-structured interviews, 4 focus group discussions, and 10 expert interviews with 76 participants. Data were collected in six affected districts with emergency mass vaccination. We included vulnerable groups (people ≥ 65 years and pregnant women) who are typically excluded from YF vaccination except during mass immunization. Data analysis was conducted using grounded theory. Inductive coding was utilized, progressing through open, axial, and selective coding. Participants relied on community sources for information about the YF mass vaccination. Information was disseminated door-to-door, in community spaces, during religious gatherings, and on the radio. However, most respondents had no knowledge of the vaccine, and it was unclear to them whether a booster dose was required. In addition, the simultaneous presidential election during the mass vaccination campaign led to suspicion and resistance to vaccination. The lack of reliable and trustworthy information and the politicization of vaccination campaigns reinforced mistrust of YF vaccines. People in remote areas affected by YF outbreaks rely on community sources of information. We therefore recommend improving health education, communication, and engagement through respected and trusted community members. Vaccination campaigns can never be seen as detached from political systems and power relations.

Community Engagement in Routine Vitamin A Supplementation: Opportunity for first Contact for Children 6-11 Months of Age in the two Health Districts in Far North Cameroon

Introduction: Vitamin A supplementation (VAS) is one of the most cost-effective interventions with the greatest impact in reducing infant and child mortality. The implementation of this intervention is done through routine mass campaigns in health facilities (HFs) following the child immunization schedule. Mass VAS campaigns are costly, donor-driven, and heavily dependent on funding for mass immunization campaigns. According to DHIS 2 (2020) data, Kaele and Guidiguis health districts had VAS coverage below 70% for 6-11 months in 2019. Results: In the two health districts, 188 people benefited from capacity building on VAS activities. That is 42 health workers (HWs) and 146 community health workers (CHWs). Of the 3520 children (50.5% girls and 45.5% boys; Guidiguis=1696 and Kaele=1824; average age= 7 months) who received their first dose of vitamin A (first contact), 2194 (62.32%) were in the HF and 1326 (37.66%) at the community (25.73% in advanced strategies and 11.93% in home visits (HVs). Conclusion: The capacity building of HWs and CHWs to be involved in VAS programs is a form of community engagement that could help catch up with children who are not accessing HFs services at the community level for VAS. We recommend further comparative research on the cost-effectiveness of community engagement in VAS programs versus mass vitamin A campaigns.

Safe at Last? Late Effects of a Mass Immunization Campaign on Households' Economic Insecurity

We study the effects of receiving immunization from COVID‐19 on households' economic insecurity. To provide causal estimates we use a fuzzy regression discontinuity design which takes advantage of the UK's immunization plan. The plan was primarily based on age, granting differential eligibility to proximate cohorts. Our estimated local average treatment effect indicates that the share of households who declared being economically insecure dropped by 41 percentage points among those who received the vaccine due to the eligibility criteria. Using a difference‐in‐discontinuity design we next document that immunization was more salient for women as well as for large households and those with children. Our results suggest that the mass immunization campaign against COVID‐19 had relevant short‐run economic effects, well beyond its expected impact on people's health.

Measles outbreak in Ethiopia amid COVID-19: an effect of war-induced hampering of vaccination and pandemic.

Measles, a highly infectious viral disease, is a leading cause of death among young children in many developing countries, including Ethiopia. Despite Ethiopia being the first large country to conduct a mass immunization campaign for measles in 2020 following coronavirus disease 2019 (COVID-19) outbreak, in which over 14.5 million children in the country were vaccinated, there was another outbreak of measles in the country in the year 2022, especially in the eastern parts of the country. According to the WHO, a total of 9850 measles cases were suspected, out of which 5806 cases were confirmed, with 56 deaths (CFR=0.6%) in Ethiopia from January to 30 September 2022. The total number of cases crossed 10000 cases by the end of October 2022. Amid COVID-19 and war times in Ethiopia posed serious challenges for the under-5 children to get access to vaccination against measles. We, therefore, urge the Ethiopian government to reach an amicable and diplomatic agreement with the civilians causing internal and intraethnic wars in the country as soon as possible, as this would prevent further hampering of measles vaccination for the Ethiopian people, most especially the children.

Pan-yellow fever virus detection and lineage assignment by real-time RT-PCR and amplicon sequencing

Yellow fever disease is a viral zoonosis that may result in a severe hemorrhagic disease. A safe and effective vaccine used in mass immunization campaigns has allowed control and mitigation against explosive outbreaks in endemic areas. Since the 1960′s, re-emergent of the yellow fever virus has been observed. The timely implementation of control measures, to avoid or contain an ongoing outbreak requires rapid specific viral detection methods. Here a novel molecular assay, expected to detect all known yellow fever virus strains, is described. The method has demonstrated high sensitivity and specificity in real-time RT-PCR as well as in an endpoint RT-PCR set-up. Sequence alignment and phylogenetic analysis reveal that the amplicon resulting from the novel method covers a genomic region whose mutational profile is completely associated to the yellow fever viral lineages. Therefore, sequencing analysis of this amplicon allows for assignment of the viral lineage.

Meningococcal A conjugate vaccine coverage in the meningitis belt of Africa from 2010 to 2021: a modelling study

As of the end of 2021, twenty-four countries in the African meningitis belt have rolled out mass campaigns of MenAfriVac®, a meningococcal A conjugate vaccine (MACV) first introduced in 2010. Twelve have completed introduction of MACV into routine immunisation (RI) schedules. Although select post-campaign coverage data are published, no study currently comprehensively estimates MACV coverage from both routine and campaign sources in the meningitis belt across age, country, and time. In this modelling study, we assembled campaign data from the twenty-four countries that had introduced any immunisation activity during or before the year 2021 (Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Côte d'Ivoire, Democratic Republic of the Congo, Ethiopia, Eritrea, the Gambia, Ghana, Guinea, Guinea Bissau, Kenya, Mali, Mauritania, Niger, Nigeria, Senegal, South Sudan, Sudan, Togo and Uganda) via WHO reports and RI data via systematic review. Next, we modelled RI coverage using Spatiotemporal Gaussian Process Regression. Then, we synthesized these estimates with campaign data into a cohort model, tracking coverage for each age cohort from age 1 to 29 years over time for each country. Coverage in high-risk locations amongst children aged 1-4 in 2021 was estimated to be highest in Togo with 96.0% (95% uncertainty interval [UI] 92.0-99.0), followed by Niger with 87.2% (95% UI 85.3-89.0) and Burkina Faso, with 86.4% (95% UI 85.1-87.6). These countries had high coverage values driven by an initial successful mass immunisation campaign, followed by a catch-up campaign, followed by introduction of RI. Due to the influence of older mass vaccination campaigns, coverage proportions skewed higher in the 1-29 age group than the 1-4 group, with a median coverage of 82.9% in 2021 in the broader age group compared to 45.6% in the narrower age group. These estimates highlight where gaps in immunisation remain and emphasise the need for broader efforts to strengthen RI systems. This methodological framework can be applied to estimate coverage for any vaccine that has been delivered in both routine and supplemental immunisation activities. Bill and Melinda Gates Foundation.

The East-West Collaboration across the Iron Curtain against Polio Epidemics: Soviet Engagement with Global Health and Poliomyelitis Vaccine Development in 1956-1964

The eradication of polio has often been portrayed as an “American story” since the heroes who invented the first polio vaccines, the primary weapon against the disease, were American medical scientists and health administrators. The main protagonists of the story are Jonas Salk and Albert Sabin, the developers of the IPV and oral poliovirus vaccine. This paper revisits the story of polio vaccine development from a Soviet perspective, focusing on an international collaboration initiated by Soviet scientists who crossed the Iron Curtain and visited the United States in the 1950s and 1960s. In 1955, Mikhail Chumakov, the head of the newly established Soviet Institute of Poliomyelitis, led a small group of Soviet medical scientists to the United States to learn about the Salk polio vaccine. The delegation gained more than just knowledge about American polio vaccine development, but they also established a regular channel for communication and collaboration between Soviet and American medical scientists that led to the national immunization program against polio in the USSR. The vaccine used for the Soviet mass immunization campaign was the Sabin live-attenuated polio vaccine that would ultimately be chosen as the weapon for global polio eradication. This paper suggests that the Soviet science diplomacy in the field of global medicine was shaped by the Soviet scientists’ experience of cooperating with their American counterparts for the Soviet polio vaccination campaign. In other words, the experience of international collaboration on the polio vaccination campaign influenced Soviet science diplomacy in the Cold War era.

Delivering actionable infodemic insights and recommendations for the COVID-19 pandemic response

Abstract Issue The COVID-19 pandemic and current recovery efforts have been complicated by a parallel infodemic. The infodemic has manifested itself in the rapid spread of questions, concerns and misinformation that can affect population attitudes and behavior harmful to health -promoting stigma and discrediting science, non-recommended treatments and cures, politicizing health programs and eroding trust in health workers and health systems. Description WHO's COVID-19 Pillar 2 (risk communication, community engagement and infodemic management) developed an integrated public health infodemic insights methodology for weekly analysis of social media, traditional media and other data sources to identify, categorize, and understand the key concerns and narratives expressed, and inform risk communication and response activities. Results The infodemic characterization, integrated analysis and insights generation consisted of a 3-step mixed-methods approach. First, data was collected from publicly available social and news media and categorized into categories of conversations by a COVID-19 public health taxonomy. Second, the dataset was analyzed and compared week-on-week to identify changes in narratives and conversation sentiment. Third, the digital infodemic intelligence was reviewed by a group of subject matter experts and triangulated with other data sources to derive infodemic insights and provide recommendations for action for the week. The methodology has been applied to inform COVID-19 response, COVID-19 vaccine demand promotion, and preparing for mass gatherings or mass immunization campaigns. Lessons The methodology for infodemic intelligence generation and integration has introduced evidence-based analytical practices for generation of infodemic insights and recommendations for action into the work of WHO. It must be further adapted for use by different health programmes and preparedness functions, and is described WHO Field Infodemiology Manual. Key messages • Health authorities can use infodemic insights to respond to people’s concerns, questions and information deficits in a timely and effective manner. • An evidence-based methodology has been developed and validated to generate infodemic insights and recommendations for action during an acute health event or emergency.

Evaluating the effect of measles and rubella mass vaccination campaigns on seroprevalence in India: a before-and-after cross-sectional household serosurvey in four districts, 2018–2020

SummaryBackgroundIndia did phased measles–rubella supplementary immunisation activities (MR-SIAs; ie, mass-immunisation campaigns) targeting children aged 9 months to less than 15 years. We estimated measles–rubella seroprevalence before and after the MR-SIAs to quantify the effect on population immunity and identify remaining immunity gaps.MethodsBetween March 9, 2018 and March 19, 2020 we did community-based, cross-sectional serosurveys in four districts in India before and after MR-SIAs. 30 villages or wards were selected within each district, and one census enumeration block from each was selected as the survey cluster. Households were enumerated and 13 children in the younger age group (9 months to <5 years) and 13 children in the older ager group (5 to <15 years) were randomly selected by use of computer-generated random numbers. Serum samples were tested for IgG antibodies to measles and rubella viruses by enzyme immunoassay.FindingsSpecimens were collected from 2570 children before the MR-SIA and from 2619 children afterwards. The weighted MR-SIA coverage ranged from 73·7% to 90·5% in younger children and from 73·6% to 93·6% in older children. Before the MR-SIA, district-level measles seroprevalence was between 80·7% and 88·5% among younger children in all districts, and between 63·4% and 84·5% among older children. After the MR-SIA, measles seroprevalence among younger children increased to more than 90% (range 91·5 to 96·0) in all districts except Kanpur Nagar, in which it remained unchanged 80·4%. Among older children, measles seroprevalence increased to more than 90·0% (range 93·7% to 96·5%) in all districts except Hoshiarpur (88·7%). A significant increase in rubella seroprevalence was observed in all districts in both age groups, with the largest effect in Dibrugarh, where rubella seroprevalence increased from 10·6% to 96·5% among younger children.InterpretationMeasles–rubella seroprevalence increased substantially after the MR-SIAs but the serosurvey also identified remaining gaps in population immunity.FundingThe Bill & Melinda Gates Foundation and Indian Council of Medical Research.

Understanding the dynamic relation between wastewater SARS-CoV-2 signal and clinical metrics throughout the pandemic

Wastewater surveillance (WWS) of SARS-CoV-2 was proven to be a reliable and complementary tool for population-wide monitoring of COVID-19 disease incidence but was not as rigorously explored as an indicator for disease burden throughout the pandemic. Prior to global mass immunization campaigns and during the spread of the wildtype COVID-19 and the Alpha variant of concern (VOC), viral measurement of SARS-CoV-2 in wastewater was a leading indicator for both COVID-19 incidence and disease burden in communities. As the two-dose vaccination rates escalated during the spread of the Delta VOC in Jul. 2021 through Dec. 2021, relations weakened between wastewater signal and community COVID-19 disease incidence and maintained a strong relationship with clinical metrics indicative of disease burden (new hospital admissions, ICU admissions, and deaths). Further, with the onset of the vaccine-resistant Omicron BA.1 VOC in Dec. 2021 through Mar. 2022, wastewater again became a strong indicator of both disease incidence and burden during a period of limited natural immunization (no recent infection), vaccine escape, and waned vaccine effectiveness. Lastly, with the populations regaining enhanced natural and vaccination immunization shortly prior to the onset of the Omicron BA.2 VOC in mid-Mar 2022, wastewater is shown to be a strong indicator for both disease incidence and burden. Hospitalization-to-wastewater ratio is further shown to be a good indicator of VOC virulence when widespread clinical testing is limited. In the future, WWS is expected to show moderate indication of incidence and strong indication of disease burden in the community during future potential seasonal vaccination campaigns.

Measles-Rubella Positivity Rate and Associated Factors in Pre-Mass and Post-Mass Vaccination Periods: Analysis of Uganda Routine Surveillance Laboratory Data

Toward 2019, Uganda experienced an extensive outbreak of measles and rubella. The Uganda National Expanded Programme on Immunization implemented a mass measles-rubella vaccination campaign aimed at halting the ongoing transmission. This study determined the changes in the disease burden thereafter. We conducted a retrospective cross-sectional study on measles-rubella positivity and its associated factors in Uganda using 1697 case-based surveillance data for 2019 and 2020 stratified into two dispensations: prevaccination and postvaccination campaigns. Statistical tests employed in STATA 15 included chi-square, Fisher’s exact, and binomial tests. Measles positivity rates in the period before and after the mass immunization campaign were 41.88% (95% CI: 39.30–44.51) and 37.96% (95% CI: 32.81–43.40), respectively. For rubella, the positivity rate in the precampaign season was 21.73% (95% CI: 19.61–23.99) and in the postvaccination season was 6.65% (95% CI: 4.36–10.00). Binomial tests indicated that postcampaign positivity rates were significantly lower than the precampaign rate for measles ( p = 0.003 ) and rubella ( p &lt; 0.001 ). Generally, age (χ2 = 58.94, p = 0.001 /χ2 = 51.91, p &lt; 0.001 ) and vaccination status (χ2 = 60.48, p = 0.001 /χ2 = 16.90, p = 0.001 ) were associated with the measles positivity rate in both pre/postcampaign periods. Rubella positivity rate was associated with vaccination status (χ2 = 32.97, p &lt; 0.001 / p = 0.001 ) in both periods and age in the precampaign season ( p &lt; 0.001 ). The measles-rubella mass campaign lessened rubella burden remarkably, but barely adequate change was observed in the extent of spread of measles. Children aged less than 9 months are at higher chances of testing positive amidst low vaccination levels among the eligible. The immunization programme must attain and maintain routine immunization coverage at 95% or more and roll out a second-dose measles-rubella vaccination to sustain the reduced disease burden.

The risk factors and pregnant women's willingness toward the SARS-CoV-2 vaccination in various countries: A systematic review and meta-analysis

IntroductionPregnant women will benefit from research on immunization during pregnancy because they will have more accurate information on the SARS-CoV-2 vaccine. The purpose of this study was to determine the risk factors and pregnant women's desire to get the SARS-CoV-2 vaccine in various countries. MethodsA search of PubMed, ProQuest, and EBSCO for related publications published (January and December 2021) on risk factors and pregnant women's desire to get the SARS-CoV-2 vaccine in various countries. The Pooled Odds Ratio (POR) were calculated using fixed and random-effect analysis. The I-squared formula was used to calculate the heterogeneity. Egger's and Begg's tests were used to identify study bias. STATA 16.0 was used for data analysis. ResultsThis study revealed good practice has the highest POR (8.99), followed by received influenza vaccine last year (2.72), high perception of SARS-CoV-2 vaccine (2.70), >35 years (2.01), sufficient information about the SARS-COV-2 vaccine (1.94), higher school education (1.84), and third trimester (1.35) with pregnant women's desire toward the SARS-CoV-2 vaccination. The heterogeneity analysis revealed homogenous among risk factors in >35 years, high perception of SARS-CoV-2 vaccine, good practice, and third trimester (I2 ≤ 50%). In the articles combined in this study, there was no indication of study bias. ConclusionThe insights of this study might help the authorities in determining the most effective strategy to deploy SARS-CoV-2 mass immunization campaigns for pregnant women.

Not Feeling Swell: Superior Vena Cava (SVC) Syndrome Falsely Attributed to COVID-19 Vaccine Reaction

BackgroundThe mass immunization campaign against Coronavirus disease 2019 (COVID-19) has resulted in more patients presenting to the emergency department (ED) with concern for a vaccine reaction. Case ReportA 68-year-old man presented to the ED reporting an allergic reaction to the COVID-19 vaccine. He initially noted swelling of his face, neck, and right arm after receiving the first dose of the vaccine. After his second dose of the vaccine, the swelling became more pronounced and prompted him to seek care. On examination, he had fullness of the neck and engorgement of the left external jugular vein, which were exacerbated when the patient raised his arms above his head, consistent with Pemberton's sign. Apart from the swelling of the head and neck, there were no other findings consistent with an allergic reaction. The presence of Pemberton's sign prompted a computed tomography scan of the chest with contrast, which revealed a paratracheal mass measuring 4.5 × 2.0 cm with marked narrowing of the superior vena cava (SVC). The patient was admitted to the hospital for SVC syndrome, and further workup revealed a non-small cell lung cancer. Why Should an Emergency Physician Be Aware of This?Patients may misattribute their symptoms to a COVID vaccine reaction when they are, in fact, experiencing a more serious underlying disease. This case highlights the importance of a thorough physical examination and maintaining a broad differential diagnosis. In this case, the presence of Pemberton's sign raised suspicion for SVC syndrome, and prompted further workup.

Population-Based Incidence of Guillain-Barré Syndrome During Mass Immunization With Viral Vaccines: A Pooled Analysis.

Misunderstanding temporal coincidence of adverse events during mass vaccination and invalid assessment of possible safety concerns have negative effects on immunization programs, leading to low immunization coverage. We conducted this systematic review and meta-analysis to identify the incidence rates of GBS that are temporally associated with viral vaccine administration but might not be attributable to the vaccines. By literature search in Embase and PubMed, we included 48 publications and 2,110,441,600 participants. The pooled incidence rate of GBS was 3.09 per million persons (95% confidence interval [CI]: 2.67 to 3.51) within six weeks of vaccination, equally 2.47 per 100,000 person-year (95%CI: 2.14 to 2.81). Subgroup analyses illustrated that the pooled rates were 2.77 per million persons (95%CI: 2.47 to 3.07) for individuals who received the influenza vaccine and 2.44 per million persons (95%CI: 0.97 to 3.91) for human papillomavirus (HPV) vaccines, respectively. Our findings evidence the GBS-associated safety of virus vaccines. We present a reference for the evaluation of post-vaccination GBS rates in mass immunization campaigns, including the SARS-CoV-2 vaccine.

Effectiveness of Hepatitis B Vaccination Campaign in Italy: Towards the Control of HBV Infection for the First Time in a European Country.

Background: In 1991, a mass immunization campaign against the hepatitis B virus (HBV) for children and teenagers was introduced in Italy. This study evaluated the impact of the immunization campaign on the incidence and modes of HBV transmission. Method: Acute HBV cases of viral hepatitis were reported to the National Surveillance System (SEIEVA). Hepatitis A cases reported to the same system were used as controls to calculate the adjusted odds ratios and the population attributable risk for potential risk factors. Results: The incidence of acute HBV declined from 5.0 in 1990 to 0.4 in 2019 per 100,000 population. The fall was almost total in people targeted by the campaign: in 2019, zero cases (100% reduction) in the age-group 0–14 years and 0.1 cases per 100,000 population (99.4% reduction) in the age-group 15–24 years were reported. In the decade 2010–2019, nearly one-fifth (19.3%) of cases occurred in foreigners. Intravenous drug use is no longer a risk factor (OR = 0.7; 95% CI = 0.5–1.02). Beauty treatments, risky sexual exposure, and household contact with an HBsAg carrier were found to be independent predictors of acute hepatitis B. Conclusions: The HB vaccination campaign proved effective in minimising acute HBV in Italy. Control of the infection is close to being reached for the first time in Europe.

Safe at Last? Late Effects of a Mass Immunization Campaign on Households’ Economic Insecurity

Safe at Last? Late Effects of a Mass Immunization Campaign on Households’ Economic Insecurity

Booster doses for inactivated COVID-19 vaccines: if, when, and for whom

Booster doses for inactivated COVID-19 vaccines: if, when, and for whom

Using Population-Based Structures to Actively Monitor AEFIs during a Mass Immunization Campaign—A Case of Measles–Rubella and Polio Vaccines

Active vaccine pharmacovigilance complements the standard passive or spontaneous surveillance system, which suffers from low reporting rates. This study aimed at utilizing population-based structures to report and profile adverse events following immunization (AEFI) with the measles and rubella vaccine (MR), or MR in combination with the bivalent oral polio vaccine (bOPV 1&3) (MR & bOPV), during mass vaccination in Uganda. Caretakers of children at home (less than 5 years) and schoolgoing children were followed up on and encouraged to report any AEFIs on day one, 2–3 days, 10 days, and 14 days after vaccination at school by their teachers and at-home, community-based village health teams. Out of 9798 children followed up on, 382 (3.9%) reported at least one AEFI, and in total, 517 AEFIs were reported. For MR, high temperature (21%), general feeling of weakness (19.3%), and headache (13%) were the most reported AEFIs, though there were variations on the days when they were reported. For the combination dose of MR & bOPV, high temperature (44%), rash (17%), general feeling of weakness (13%), and diarrhoea (8%) were the most common adverse events following immunization reported by caretakers. All 382 children cleared the AEFIs within 2 days, with 343 (90%) children reporting mild or moderate AEFIs and only 39 (10%) reporting severe AEFIs. The reported AEFIs are known and are mentioned in the vaccine leaflets with similar severity classification. Rates of AEFIs differed with the number of days after receiving the immunization. Conclusion: Active surveillance for AEFIs provides additional important information to national vaccine regulatory bodies. It reassures the public that vaccines are safe and that their safety is being taken seriously in Uganda, which would improve vaccine acceptability and confidence in the health system. Piggybacking on existing structures such as village health team members (for children at home) and teachers (for schoolgoing children) facilitates reaching vaccine recipients and increases reporting rates. Therefore, studies using active reporting of AEFIs should be conducted at regular intervals to report the overall incidence of AEs and to monitor trends and changes.