This review explores and positions the value of serology testing to support current immunization policies and the broader policy response to the coronavirus disease 2019 (COVID-19) crisis in Europe. We applied an exploratory approach to analysing existing evidence, international recommendations, and national policies using desk research from secondary sources, document analysis, and expert information. Regional and country-level resources from five focus countries were included: France, Germany, Italy, Spain, and the United Kingdom. Seven experts in the fields of COVID-19 immunization, serology testing, seroepidemiology, and vaccine safety and effectiveness studies contributed to the review and convened in two online panel sessions. The paper includes an overview of (1) the impact of the pandemic to date, (2) testing strategies, (3) COVID-19 vaccination policies, (4) lessons on using serology testing to support immunization, (5) current policies and recommendations on the use of a serology testing strategy, and (6) implementation barriers and challenges. Finally, this paper also provides a set of knowledge-based recommendations to advance the effective and timely inclusion of serology testing and resolve impeding knowledge gaps. The recommendations herein are intended to support timely decision-making, raise awareness, guide advocacy initiatives, and inspire future studies.

Respiratory syncytial virus (RSV) is the main cause of low respiratory tract infections in infants under one year of age. In the 2023/2024 season, the monoclonal antibody nirsevimab was available to protect children from RSV, and Spain has become one of the first countries worldwide to implement this strategy. It is essential to evaluate the results of this first campaign and different characteristics of the immunized population in order to plan next campaigns, especially for countries that are going to include this immunization. Our coverage was high (91.5% for those born during the season and 88.3% globally). For those born during the season, only 4.9% preferred not to immunize at the maternity hospital, which meant an average delay of 27.45 days. We observed a lower coverage in the population of immigrant origin. There was a rapid pace of immunization, since for those born before the beginning of the campaign the mean to be immunized was 15.63 days, without differences between healthy and at-risk children. This allows immunization before the RSV season (90% of the catch-up children had been immunized on November 3). The average age at which all the immunized children have received nirsevimab was lower in healthy children compared to those with risk conditions (49.65 versus 232.85 days). For those born during the campaign, the average age was also lower in healthy children (3.14 versus 14.58 days). In conclusion, we consider that the implementation of the immunization strategy with nirsevimab in the Region of Murcia, Spain, has been a success.

During the 2022-2023 season, the Region of Murcia (an autonomous community of Spain) introduced the influenza vaccination campaign in children aged 24-59 months with the live-attenuated influenza nasal spray vaccine. To expand coverage, a pilot study was conducted to include the 3- to 4-year population in 24 public schools. The aim of the study was to assess the experiences of parents and teachers involved in the project. This was a psychosocial qualitative study in which information was collected from a cohort of 23 parents and 17 teachers who attended three and two focus group sessions, respectively. A high degree of satisfaction with the school-located influenza vaccination program was consistently reported. The teachers reported creating a friendly environment and acting as companions to support children in the absence of their parents. They also considered the intranasal route, which avoids intramuscular puncture, as a facilitating element that turned the vaccination process into a kind of game. Parents emphasized the importance of vaccination to protect their children, and secondarily, to ensure protection of the family nucleus. Some parents who had their children already vaccinated in the health care center reported preference for the school setting, probably selecting this option in the future. The availability of school-based influenza vaccination promoted greater equity in accessing the vaccine and facilitated family reconciliation. To optimize coverage and minimize potential reluctance, providing the necessary information to parents both before and after vaccination was considered. School-located influenza vaccination was feasible and is a valuable strategy to be implemented in future campaigns.

Respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infections in young children and associated with most bronchiolitis- and pneumonia-related hospitalizations. A new preventive monoclonal antibody (MAb), nirsevimab, has been launched in the United States, Luxembourg, and France, and was recently approved to be given in a population-based manner throughout Spain. This study aimed to have a first pre-immunization insight into the Spanish parental knowledge about bronchiolitis, RSV, and nirsevimab immunization. Parents in Murcia with children <2 years of age up to the date of September 1, 2023, were selected to complete a questionnaire. The primary endpoint was the parental knowledge about bronchiolitis, RSV, and nirsevimab. A total of 3,217 responses were analyzed. The majority (95.8%) were aware of bronchiolitis. Meanwhile, 46.6% of the respondents knew about RSV, most of them only after the first child's birth. Information about RSV or bronchiolitis was mainly obtained from family members, with only 4.8% reporting having been informed by Health care Professionals (HCPs). Only 11.2% of respondents were aware of nirsevimab. Nonetheless, these were not entirely satisfied with the information received (score of 3.3 out of 5) and shared that HCPs should be the primary source of information. The present survey then highlights the need for better and more efficient educational strategies directed to all parents/legal guardians. It also sheds some light on the different factors that should be considered to improve awareness of RSV immunization to decrease its burden in Spain and beyond.

Outbreaks in temporary camps are an important risk for the health of the displaced population. The town of Lorca (Murcia, Spain) suffered 2 earthquakes on May 2011 that required the re-housing of 1,424 victims in a temporary camp. Following 4 cases of chickenpox control measures were adopted among the displaced population. These measures included vaccination against chickenpox; due to the existence of cases of measles in adjacent regions, it was decided to offer measles, mumps and rubella (MMR) vaccination as well. The immunization campaign was performed during 2 d (3 to 4 d after the first case). The immunity status of 1,041 (73,1%) of the residents was reviewed. Being vaccinated 523 (67%) against chickenpox and MMR, 133 (17%) against only MMR and 124 (16%) against only chickenpox. We consider the action taken was a success, as only 4 additional cases of chickenpox were subsequently recorded in the campsite, being avoidable only one of them. There is a major risk of outbreaks in a disaster situation. Because of this, conducting preventive actions are indicated to avoid doing worse this critical.

The high burden of influenza in children has driven numerous countries towards universal vaccination of healthy children from 6 to 59 months of age. The Region of Murcia was one of the pioneer Spanish regions to conduct a universal vaccination campaign and to use live-attenuated intranasal vaccine (LAIV) if age appropriate. This study aims to evaluate the parents’ likeliness to vaccinate their children and to compare the profile of vaccinating/non-vaccinating parents. This study was designed as a prospective, real-world, survey-based data collection in the 2022–2023 season campaign. This study’s sample was selected from those children whose information was available in the local Public Health System databases PERSAN and VACUSAN. Children received LAIV or intramuscular vaccine (IIV) depending on their age as per standard practice. The parent self-vaccination/intention to vaccinate themselves in this campaign (OR = 4.75), the compliance with the official vaccination schedule (OR = 3.41), and the prescription of antibiotics more than twice in the previous year (OR = 2.24) were strongly associated with children’s vaccination. Overall, vaccinating parents were very satisfied with the vaccine (IIV: 67.5% vs. LAIV: 68.8%, p = 0.320), and most parents would rather have their children vaccinated with LAIV for the next campaign (43.0%). The main reasons for vaccinating were to protect the child (LAIV: 85.9% vs. IIV: 89.4%), and the predominant reasons for not vaccinating were a lack of healthcare professional recommendation (30.9%), and lack of information about the vaccination campaign (21.5%) and the vaccine itself (21.0%). The clinical context of parents and children was determinant in decision making, which was also influenced by the presence or absence of recommendation by healthcare professionals. Parents were generally very satisfied with the vaccine and showed their preference towards LAIV for future campaigns.