National Immunization Program Research Articles

Invasive meningococcal disease in South-Eastern European countries: Do we need to revise vaccination strategies?

ABSTRACT Invasive meningococcal disease (IMD) is an acute life-threatening infection caused by the gram-negative bacterium, Neisseria meningitidis. Globally, there are approximately half a million cases of IMD each year, with incidence varying across geographical regions. Vaccination has proven to be successful against IMD, as part of controlling outbreaks, and when incorporated into national immunization programs. The South-Eastern Europe Meningococcal Advocacy Group (including representatives from Croatia, the Czech Republic, Greece, Hungary, Poland, Romania, Serbia, Slovenia and Ukraine) was formed in order to discuss the potential challenges of IMD faced in the region. The incidence of IMD across Europe has been relatively low over the past decade; of the countries that came together for the South-Eastern Meningococcal Advocacy Group, the notification rates were lower than the European average for some country. The age distribution of IMD cases was highest in infants and children, and most countries also had a further peak in adolescents and young adults. Across the nine included countries between 2010 and 2020, the largest contributors to IMD were serogroups B and C; however, each individual country had distinct patterns for serogroup distribution. Along with the variations in epidemiology of IMD between the included countries, vaccination policies also differ.

A comparative analysis of vaccine lists, prices, and candidates, and the national immunization program between China and the United States

Vaccines have an essential role in preventing infectious diseases and reducing the burden of disease. The differences in vaccine lists and prices, and the National Immunization Program (NIP) and vaccine development between China and the United States (US) in conjunction with epidemiologic data on infectious diseases were systematically compared. The epidemiologic data of infectious diseases in 2019 were extracted from the China National Health Commission and the US Centers for Disease Control and Prevention (CDC). The vaccine list was identified from the China National Medical Products Administration and US Food and Drug Administration databases. Vaccine prices were obtained via the China government procurement platform and the US CDC. The NIP vaccines for China and the US were obtained from the China and US CDCs. Vaccine candidates investigated in 2015-2022 were identified from the China Clinical Trial Registry Platform and the US clinicaltrials.gov database. Differences in the incidence of infectious diseases between China and the US were detected with both countries facing a lack of available vaccines for prevention of many diseases. The number of listed vaccines and preventable diseases in China was 59 and 36, respectively, which was higher than the US (45 and 31, respectively). The median price of NIP vaccines in China was significantly lower than the price in the US (median: $3.8 vs. $20; P<0.001); however, there was no significant difference in the price of non-NIP vaccines (median: $68 vs. $86; P=0.498). Vaccines developed by local manufacturers were less expensive than imported products despite the absence of significant differences (median: $16 vs. $31; P=0.180). The number and types of NIP vaccines used to prevent infectious diseases in China were lower than the US. The majority of vaccine candidates in China were not novel compared to the US. Vaccines marketed in China for infectious diseases were comparable to the US. Our findings suggest that China should further expand NIP vaccines and incentive research and development on novel vaccines to improve accessibility based on infectious disease epidemiology.

Twenty Years of Progress and the Way Forward: Immunization Registry Information System in Korea.

The National Immunization Program in The Republic of Korea offers mandatory and free vaccinations to children under 12, regulated by the Infectious Disease Prevention and Control Act. Tracking vaccination coverage is crucial for population protection and public health strategies. Since 2002, the Immunization Registry Information System (IRIS) has been used nationwide to capture vaccination data. This study reviewed documents related to IRIS's establishment and development. The Republic of Korea legally supports IRIS's construction and data collection, integrating vaccination data with the Ministry of the Interior and Safety's resident registration to minimize errors. This collaboration also facilitates cost reimbursement and digital registration, promoting wider vaccination coverage. IRIS manages expense claims once vaccination details are logged, and authorized medical institutions can access these records in real-time. Since 2015, the Korea Disease Control and Prevention Agency has been compiling annual data on national vaccination coverage. IRIS also sends automated reminders in 12 languages, reports adverse effects, and issues vaccination certificates. However, IRIS lacks integration between vaccine and disease registries, unlike countries such as England, Denmark, and the Netherlands. Improving integration capabilities could enhance IRIS's support for public health through an integrated information system.

Is health expenditure on immunisation associated with immunisation coverage in sub-Saharan Africa? A multicountry analysis, 2013–2017

ObjectivesThe designing of contextually tailored sustainable plans to finance the procurement of vaccines and the running of appropriate immunisation programmes are necessary to address the high burden of vaccine-preventable diseases...

Program eliminacije morbila u Evropi

The use of a safe and effective measles vaccine in national immunization programs has resulted in a reduction in the number of deaths from the disease, although measles remains one of the leading causes of death in children under 5 years of age in underdeveloped and developing countries. After the successful eradication of smallpox, as well as the results achieved in the eradication of poliomyelitis at the global level, the process of measles elimination was initiated using the previously known strategies. In both American regions of the World Health Organization (WHO), the elimination of measles has been successfully verified, while in the WHO European Region, up to 2020, elimination has been verified in 29 out of 53 countries. The main challenges in the process of measles elimination are reaching and maintaining high immunization coverage, reaching and maintaining the values of surveillance indicators, implementing additional immunization of unvaccinated and incompletely vaccinated persons, solving serious problems such as the occurrence of measles epidemics in vulnerable groups, endemic maintenance of the disease, re-establishment virus transmission, determination of chains of transmission, genotyping of agents, impact of measures to control the COVID-19 pandemic. Bearing in mind the mentioned problems, the WHO has decided to postpone the elimination of measles in the WHO European Region to the year 2030.

The impact of strategies for increasing vaccination coverage in children: A community clinical trial

The Brazilian National Immunization Program (PNI) has been consolidating itself as one of the most relevant interventions in public health. Paradoxically, great challenges arise for the PNI. The phenomenon of falling vaccine coverage is observed not only in Brazil, but in several countries. In the year 2021, faced with the unfavorable scenario of a drop in vaccination coverage, the State Department of Health, and the Federal University of Minas Gerais joined forces to implement a research-intervention project. This study aimed to evaluate the impact of this intervention on vaccination coverage in children under 2 years of age and on indicators of immunization work processes. This is a community clinical trial carried out in 212 municipalities in the state. Workshops were held and Municipal Action Plans were created. Vaccination coverage data were obtained from the National Immunization Program Information System (SIPNI) and evaluated using the Mann-Whitney U Test and the McNemar Test. Work process indicators were evaluated using the Friedman and Wilcoxon tests. The results demonstrate an important improvement for most of the indicators in the three analyzed times, with statistical significance and an increase in medians and interquartile ranges. Among the indicators that showed the best performance, it is possible to mention those related to the active search by the Community Health Agent. Regarding vaccine coverage, for all immunobiologicals analyzed, there was an increase in the percentage of municipalities that reached targets when comparing the years 2022 and 2021, except for hepatitis A. The intervention research had a positive impact on vaccine coverage of children under 2 years of age and on indicators of immunization work processes in municipalities in the state of Minas Gerais, Brazil.

Incidence of vaccine-related anaphylaxis from Brazil's National Immunization Program

Incidence of vaccine-related anaphylaxis from Brazil's National Immunization Program

Perceptions of childhood immunization in São Paulo: quantitative-qualitative cross-sectional study.

Vaccination hesitation spans from historical diseases such as smallpox to the current challenges with the coronavirus disease (COVID-19). In Brazil, vaccination faces obstacles related to trust and convenience. Despite the National Immunization Program, fear of adverse effects as well as misinformation challenge confidence in vaccines, and anti-vaccine movements have gained momentum. This study investigated childhood vaccine refusal, including COVID-19 vaccines, by comparing the reasons for and sociodemographic differences between vaccinated individuals and those who hesitated or refused immunization. A cross-sectional study was conducted in São Paulo, Brazil, using questionnaires administered during pediatric consultations between January and April 2023. This study investigated vaccine hesitancy and the attitudes of parents and caregivers of children (0-12 years) towards vaccines. The questionnaire was administered during routine pediatric consultations at three different locations, each with 50 participants for a total of 150 participants, to avoid selection bias. Marked differences were evident among caregivers in terms of sex, race, income, education, and religion, which influenced their attitudes toward vaccination. There was an increase in the refusal of seasonal vaccinations and a significant distrust of the efficacy of the COVID-19 vaccine (52%), with concerns about its side effects. Although most patients did not stop vaccination, significant delays occurred, especially in the clinical setting (58%). This study emphasizes the importance of childhood health decisions, indicating the need to build trust in vaccines, tailor health policies, and investigate the causes of distrust to promote childhood immunizations.

Gender-Neutral HPV Vaccine in India; Requisite for a Healthy Community: A Review.

Human papillomavirus (HPV) affects approximately 80% of individuals, irrespective of gender, and is implicated in various cancers. Existing HPV vaccines, while safe and effective, do not sufficiently protect males when administered solely to females. This review, triggered by the urgent need to address this gap and reduce the associated stigma, aims to evaluate the introduction of a gender-neutral HPV vaccine, GARDASIL-9, in India. The primary objective is to assess the necessity and feasibility of incorporating the gender-neutral HPV vaccine into India's national immunization program. This integration is crucial to ensure equitable access for all children and to mitigate the substantial burden of HPV. A literature search was conducted using databases such as Google Scholar, PubMed, government websites, and relevant publications. Keywords included "gender-neutral vaccine", "HPV vaccine", and "Indian population". The central research question guiding this review is: How necessary and feasible is the inclusion of a gender-neutral HPV vaccine in India's national immunization schedule to ensure equitable access for all children and reduce the HPV burden? The review inclusion criteria comprised studies addressing the prevalence of HPV infections, HPV vaccination awareness among both genders, the cost-effectiveness of gender-neutral vaccines, current HPV vaccination status, and future perspectives specific to India. Studies not meeting these criteria were excluded. The review highlights that introducing a gender-neutral HPV vaccine in India is imperative. Including males in vaccination efforts significantly reduces the overall disease burden and helps in reducing the stigma associated with HPV. A comprehensive vaccination program, bolstered by education and awareness campaigns, and its inclusion in the national immunization schedule is essential. This approach ensures equitable access to the vaccine for all children, fostering a healthier community, preventing HPV-related cancers, and enhancing public health outcomes in India.

An Outbreak of Serogroup Y Meningococcal Meningitis in a Private Secondary Vocational School - Guangzhou City, Guangdong Province, China, 2023.

The inclusion of meningococcal vaccines in the National Immunization Program (NIP) over several years has significantly reduced the incidence of meningococcal meningitis in China to historic lows. Worldwide, there has been a diversification of meningococcal serogroups, leading to a shift in dominant serogroups in China from serogroup A to serogroups C and B, accompanied by a rise in reports of serogroups Y and W. An outbreak of serogroup Y Neisseria meningitidis (Nm) in a secondary vocational school involved a single confirmed severe case and 24 individuals with laboratory-confirmed Nm carriage. Epidemiological investigation revealed that the outbreak was localized to the classroom of the confirmed case. Prolonged close contact within a confined space was identified as a significant risk factor for Nm transmission. The genotype sequence identified was type 1655 (ST-1655), which is categorized under clonal complex 23 (CC-23) and bears resemblance to 8 previously confirmed cases of serogroup Y meningococcal meningitis within Guangdong Province. This suggests that serogroup Y infections continue to sporadically emerge and have become prevalent strains. This outbreak underscores the critical need to enhance surveillance of meningococcal serogroups and population carrier, and advocate for vaccination with MenY-containing vaccines.

Vaccination practices and knowledge among adults with hemoglobinopathies in Greece: a nationwide survey.

Hemoglobinopathies, such as sickle cell disease and thalassemia, are genetic disorders that affect hemoglobin structure or production, leading to various health complications, including an increased risk of infections. Vaccinations play a crucial role in managing these conditions by providing essential protection against preventable diseases. Ensuring timely and appropriate immunizations is vital for reducing infection-related morbidity and improving the overall health and quality of life for affected individuals. Our objective was to assess vaccination coverage, as well as knowledge, attitudes, and practices toward vaccination in Greek patients with hemoglobinopathies. A nationwide survey of hemoglobinopathy patients in Greece using a 37-item questionnaire was conducted anonymously via Google Forms. It covered demographics, previous vaccinations, vaccine-preventable infections, beliefs about vaccines, and antibiotic prophylaxis post-splenectomy. The survey was distributed through Thalassemia and Sickle Cell Units and organizations. Participants were predominantly university-educated married women aged 30-50 years with transfusion-depended thalassemia (n = 149, 60.5%) or sickle cell anemia (n = 52, 21.1%). Reported childhood vaccination rates aligned with Greece's national immunization program. However, adult coverage was suboptimal across all age groups for measles (10%), varicella (27%), zoster (2% for over 50 years old individuals), hepatitis A (13.9% of those with chronic liver disease) and hepatitis B (41%), pneumococcal (81.3%), meningococcal (37%), tetanus (20.3%), and influenza (67.1%) vaccines compared to guidelines. Participants relied predominantly on healthcare providers for vaccine information but perceived limited engagement. Those over age 50 demonstrated lower adult vaccination rates and higher misconceptions compared to younger cohorts. Addressing educational and access gaps could help protect this vulnerable population. Our findings highlight the need for coordinated efforts to optimize adult immunization for those with hemoglobinopathies.

Educational Interventions Planned to Increase Human Papillomavirus Vaccination Acceptance among Adolescents and Their Parents in Asia: A Systematic Literature Review

Abstract One of the Global strategies to accelerate the elimination of cervical cancer is vaccinated with HPV vaccines by age 15 years by 2030. Recent studies showed that increased vaccine-related knowledge associated with HPV-vaccine acceptance and intention to vaccinate. In other words, insufficient information is the main barriers to vaccination acceptance. Accordingly, interventions that improve understanding of HPV vaccines may increase HPV vaccination coverage. The aim of this study was to summarize educational interventions designed to increase HPV vaccine acceptance in adolescents and their parents. We searched the databases of PubMed, Science Direct and Google Scholar on October-December 2020. We performed a literature search for published articles in English and searched relevant keywords (papillomavirus vaccines and knowledge, acceptance, intervention studies, communication, education). Our search was limited to studies targeting populations from Asian countries. Thirteen interventional studies performed in Asian countries met the inclusion criteria. Five studies used PowerPoint presentation and slide presentation as an educational intervention. Two studies applied written media that was an educational sheet that provided information on HPV vaccines. Two studies used social media and mobile for educational intervention. Two studies designed the educational intervention in 30 minutes and 1 hour lecture which following by question and answer. Two of studies conducted two educational interventions. First one was applied PowerPoint presentation and social media and the second one used lecture and group discussion. HPV vaccine acceptance is varied widely between studies across Asian countries. Increasing public awareness about HPV vaccines, will increase acceptance. Increasing acceptance, will lead to demand people for health policy makers to will introduce HPV vaccines into their national immunization program.

Establishment of Safety Monitoring System for Vaccines Not Included in the National Immunization Program in Korea.

In Korea, there are no surveillance programs for vaccines that are not included in the national immunization program (NIP), and vaccine safety monitoring in the adult population is inadequate. This study aimed to establish a safety monitoring system for non-NIP vaccines in adults. Frequently administered non-NIP vaccines were selected. Individuals were included if they received at least one of the selected vaccines at a participating institution and provided informed consent. Solicited and unsolicited adverse events were monitored using questionnaires sent through text messages on days 1, 3, 7, 28, and 90 post-vaccination. Selected adverse events of special interest (AESIs) were monitored monthly by retrospective review of electronic medical records. Causality was assessed according to the Korea Disease Control and Prevention Agency guidelines. Four vaccines (tetanus-diphtheria-pertussis [Tdap], pneumococcal conjugate 13-valent [PCV13], live zoster vaccine [ZVL], and recombinant zoster vaccine [RZV]) were selected, and their safety profiles were monitored at four tertiary hospitals and 10 primary care clinics. The response rates of the questionnaires on post-vaccination days 1, 7, 28, and 90 were 99.2%, 93.6%, 81.0%, and 48.7%, respectively. Of 555 AESI identified over 10 months, 10 cases received one of the selected non-NIP vaccines within 90 days of the event. We are establishing the first safety monitoring system for selected non-NIP vaccines in Korea since September 2022 and report its progress as of July 2023. However, continuous government support is essential for its maintenance and improvement.

Long-term surveillance of invasive pneumococcal disease: The impact of 10-valent pneumococcal conjugate vaccine in the metropolitan region of Salvador, Brazil

BackgroundIn 2010, Brazil introduced the ten-valent pneumococcal conjugate vaccine (PCV10) in the national infant immunization program. Limited data on the long-term impact of PCV10 are available from lower-middle-income settings. We examined invasive pneumococcal disease (IPD) in Salvador, Bahia, over 11 years. MethodsProspective laboratory-based surveillance for IPD was carried out in 9 hospitals in the metropolitan region of Salvador from 2008 to 2018. IPD was defined as Streptococcus pneumoniae cultured from a normally sterile site. Serotype was determined by multiplex polymerase chain reaction and/or Quellung reaction. Incidence rates per 100,000 inhabitants were calculated for overall, vaccine-type, and non-vaccine-type IPD using census data as the denominator. Incidence rate ratios (IRRs) were calculated to compare rates during the early (2010–2012), intermediate (2013–2015), and late (2016–2018) post-PCV10 periods in comparison to the pre-PCV10 period (2008–2009). ResultsPre-PCV10, overall IPD incidence among all ages was 2.48/100,000. After PCV10 introduction, incidence initially increased (early post-PCV10 IRR 3.80, 95% CI 1.18–1.99) and then declined to 0.38/100,000 late post-PCV10 (IRR 0.15; 95% CI 0.09–0.26). The greatest reductions in the late post-PCV10 period were observed in children aged ≤2 years, with no cases (IRR not calculated) and those ≥60 years (IRR 0.11, 95% CI 0.03–0.48). Late post-PCV10, significant reductions were observed for both PCV10 serotypes (IRR 0.02; 95% CI 0.0–0.15) and non-PCV10 serotypes (IRR 0.27; 95%CI 0.14–0.53). Non-PCV10 serotypes 15B, 12F, 3, 17F, and 19A became predominant late post-PCV10 without a significant increase in serotype-specific IPD incidence compared to pre-PCV10. ConclusionSignificant declines in IPD, including among adults not eligible for vaccination, suggest direct and indirect protection up to nine years after PCV10 introduction, without evidence of significant replacement disease. Continued surveillance is needed to monitor changes in non-vaccine serotypes and inform decisions about introducing higher valent PCVs.

Tendência temporal das coberturas vacinais no primeiro ano de vida no Brasil

ABSTRACT Objective: The aim of this study was to analyze the temporal trends in vaccination coverage (VC) during the first year of life of children in Brazil. Methods: Data on VC for the first year of life from 2011 to 2020 for Bacille Calmette-Guerin (BCG), hepatitis B, polio, pentavalent, and triple viral vaccines at the national, regional, and state levels were obtained from the Information System of the National Immunization Program. Trends were analyzed using Prais-Winsten generalized linear regression models and average annual percent change (APC) estimates. Results: Decreasing trends were observed for the BCG (APC −3.58%; p<0.05), pentavalent (APC −4.10%; p<0.05), polio (APC −2.76%; p<0.05), and triple viral (APC −2.56%; p<0.05) vaccines in the country. Hepatitis B vaccine was the only vaccine that displayed stationary behavior (APC −4.22%; p>0.05). During the study period, no increasing trends were observed in any territory or vaccine. Conclusions: This study shows a recent significant reduction and decreasing trends in VC during the first year of life of children in Brazil, indicating the need for interventions to curb this ongoing phenomenon and to recover acceptable VC rates in the country.

Reliability of information recorded on the National Immunization Program Information System.

To analyze the reliability of records held on the National Immunization Program Information System (SI-PNI) in a subsample of children included in the national vaccination coverage survey in Brazilian state capitals and Federal District in 2020. This was a study of agreement between data recorded on vaccination cards (doses and dates) and on the SI-PNI for 4050 children with full coverage at 24 months. Data on 3587 children were held on the SI-PNI, with losses of 11% (95%CI: 10;12). Total agreement between doses and dates in the two sources was 86% (95%CI: 86;87), however taking each dose and vaccine individually, variation was greater, with 32% of data in only one source. Part of the information was not recorded, but the discrepancy can be considered small. Nonetheless, underrecording of doses and children can compromise vaccination coverage estimates, altering the numerator and denominator data. Subsample of 4,050 children, among those completing the full schedule at 24 months studied in the national survey, 11% had not been recorded on the SI-PNI, 32% had unrecorded doses (doses or dates) and there was 8% disagreement between vaccination cards and SI-PNI records. Recognizing the difficulties faced by the SI-PNI and the discrepancies between sources is essential for adopting initiatives to improve data quality, so as to avoid inaccurate estimates of childhood vaccination coverage. This study is expected to contribute to improving the quality of records and the usability of data for monitoring vaccination coverage of the immunization program from the local to the national level.

Vaccination coverage and abandonment among children under two years old in Brazil: a time-series study.

To analyze the vaccination coverage and abandonment rates among children under two years old in Brazil, from 2015 to 2021. A time-series ecological study. The dependent variables of the research were "vaccination coverage" and "abandonment rate", both assessed by Brazilian region. The data were extracted in July 2022 from the Information System of the National Immunization Program. The Prais-Winsten technique was used for the trend analysis, with the aid of the STATA 16.0 software. The mean vaccination coverage in Brazil was 76.96%, with a decreasing trend during the period (Annual Percent Change=-5.12; confidence interval - CI95% -7.81; -2.34); in 2015, the rate was 88.85% and it dropped to 62.35% in 2021. In turn, the overall abandonment rate was 24.00% in 2015 and 9.01% in 2021, with a mean of 10.48% and a stationary trend (Annual Percentage Change=-9.54; CI95% -22.92; 6.12). In 2021, all the vaccines presented coverage values below 74.00% in the country. The vaccination coverage rate trend among children under two years old was stationary or decreasing for all the immunobiologicals in all Brazilian regions, with the exception of yellow fever in the South and Southeast regions. There was an increase in the abandonment rate trend for the Meningococcal C vaccine in the country and, specifically in relation to the regions, for BCG in the North, Northeast, and Midwest and for Meningococcal C in the North and Northeast.

Impact of National Immunization Strategies on Vaccine-Preventable Diseases - China, 1950-2021.

The incidences of vaccine-preventable diseases (VPDs) included in the Expanded Program on Immunization in China have decreased significantly in recent decades. This study summarizes the national incidences of nine VPDs and the seroprevalence of hepatitis B surface antigen (HBsAg) under different immunization strategies from 1950 through 2021 in China. The sharpest decreases in VPD incidence and under-5-year HBsAg seroprevalence occurred during the latest stage of the National Immunization Program. The decreases in VPD incidence were most prominent among children under five years of age. These findings provide valuable insights for vaccine value assessment and emphasize the importance of implementing immunization strategies in targeted populations.

Reliability of information recorded on the National Immunization Program Information System

RESUMO Objetivo Analisar a confiabilidade dos registros no Sistema de Informação do Programa Nacional de Imunizações (SI-PNI) em uma subamostra de crianças incluídas no inquérito nacional de cobertura vacinal nas capitais brasileiras e no Distrito Federal, em 2020. Método Estudo de concordância entre registros nas cadernetas (doses e datas) e no SI-PNI para 4.050 crianças com esquema completo aos 24 meses. Resultados Foram localizados registros de 3.587 crianças no SI-PNI, havendo 11% (IC95%10,0;12,0) de perdas. A concordância total entre doses e datas nas duas fontes foi de 86% (IC95% 86,0;87,0), porém para cada dose e vacina a variação foi maior, com 32% de dados só em uma fonte. Conclusão Parte das informações não vem sendo adequadamente registrada, mas para os dados existentes nas duas fontes a discordância pode ser considerada pequena. O sub-registro de doses e crianças pode comprometer as estimativas de cobertura vacinal, alterando os dados do numerador e do denominador.

Homologous equivalence study of immunogenicity after third dose of Covid-19 vaccine (recombinant) with an interval of six months after the second dose, comparing the interval of eight and 12 weeks between the first two doses.

In response to the coronavirus disease 2019 (Covid-19) pandemic, Brazil authorised the Astra Zeneca/Fiocruz vaccine in January 2021. As the Delta variant emerged in May 2021, interval between vaccine doses was adjusted. By September 2021, the Brazilian National Immunisation Program recommended a booster dose for individuals over 70, and later expanded the recommendation to all adults. Assess the equivalence of IgG antibody response against the Covid-19 S protein before and approximately 28 days after the third dose of a Covid-19 recombinant vaccine. Two groups received initial two doses with intervals of eight and 12 weeks. This is a phase IV clinical study, uncontrolled, non-randomised. The study proposes calculating the ratio of geometric means titres (GMT) 28 days after the third dose, with a target ratio of confidence interval (CI) between 0.77 and 1.3. In the primary endpoint, there was no equivalence between the eight- and 12-week intervals with a slight variation favouring the eight-week group. Post-third dose, both groups showed increases titres at 28 days, three months, six months and 12 months. Both groups responded similarly to Delta and Omicron BA.1, with a more significant increase for Delta. The study showed strong and consistent immune response in all age groups receiving the Covid-19 recombinant vaccine. Third dose elicited an increase in GMT by at least three times aligned with Ministry of Health strategies emphasising Bio-Manguinhos crucial role in pandemic control in the country.