Prevention and control of communicable diseases is crucial to ensure global health security.1 Vaccination represents a fundamental tool to limit the progression and dissemination of infectious agents, including influenza and COVID-19.2 Successful vaccination strategies depend on public perceptions, including risk perceptions, and trust.3 Despite the well-established links between public perceptions and successful vaccine adoption by the population, a comprehensive evaluation of the perceptions of the Portuguese population in the post-COVID-19 era, particularly those with a previous diagnosis of Chronic Respiratory Disease (CRD), is still lacking.

The main goal of this study was to assess the perceptions of the Portuguese population regarding vaccination (in general, and against flu and COVID-19) and particularly analyze the views of those individuals with a previous CRD diagnosis.

We designed an observational, descriptive, cross-sectional study with a quantitative approach.

To assess the perceptions of the Portuguese population regarding vaccination, we developed a questionnaire composed of demographic questions, semi-open questions, or in Likert scale.

Telephone interviews were conducted by the research team. Respondents were informed about the context and objectives of the study and the individual voluntary consent to participation was obtained. Study was reviewed and approved by the competent Institutional Review Board (NOVAIMS Ethics Committee): Project N°: STAT2023-10-123709.

The data collection period took place between 1 and 30 August 2022. The sample was post-stratified according to the distribution of the population by gender, age, and NUTS II regions. The results are presented with a confidence level of 95 %. Significant statistical differences are indicated, when the number of observations is greater or equal to 30 and the difference between the results of groups/segments exceeds the margins of error of the estimates (p ≤ 0,05).

We obtained 605 valid, fully answered questionnaires from Portuguese citizens, residing in mainland Portugal and aged between 18 and 74 years old (margin of error of 0.23 points, 95 % confidence level). Characterization of the study population is presented in Table 1. More than half of the respondents were female, 39,4% were aged 35–54 years old and 37,2 % were from the North of Portugal. Overall, 49,8 % of participants were married, 34,3 % had completed higher education and 31,1 % had a household net monthly income of 706 – 1410 €. Approximately one quarter of the study population (24,8 %) had a previous diagnosis of CRD.

Perceptions of the Portuguese population on vaccination are presented in Table 2. Most participants agreed that vaccines are important to protect others (97,2 %) and that they are tested rigorously before being authorized (90,8 %). Participants without CRD expressed higher agreement than participants previously diagnosed with CRD (92,1 versus 87,0 respectively, p = 0,105) (Table 2). Most participants also agreed that vaccines can produce serious side effects (74,8 %). Most study participants (64,4 %) had not been vaccinated against the flu in the previous 12 months. The flu vaccination coverage was found to be higher in eligible individuals (65,3 % for those with 60+ years of age; 25.2 % in younger individuals; p < 0,001) (data not shown in Table 2). Participants with a previous CRD diagnosis stood out as those with a higher frequency of vaccination against the flu (40,7 % to 33,9 %, p = 0,137). Furthermore, flu vaccination was found to be more prevalent among older patients (56,8 % in the 55–74 years old group versus 26,6 % and 22 % in the 18–34 and 35–54-year-old groups, respectively; p < 0,001) (data not shown in Table 2). Moreover, flu vaccination tends to be less prevalent in participants without income (0 %) in comparison to other income levels (ranging from 14,7 % to 42,6 %). No association was found between level of education and flu vaccination status. More than half of the participants believe that the flu vaccine is not necessary for young and healthy people (54,7 %). Slightly more than half of the participants believed the flu vaccine could transmit the flu (51,7 %). This perception was lower among individuals with higher education (34.4 %) in comparison to individuals with lower levels of education (varying between 53.6 % and 78.4 %, p < 0,001) (data not shown in Table 2).

Participants agree that vaccination is crucial during the flu season (8,2, on a scale of 1 to 10) and were satisfied with the effectiveness of vaccines in fighting influenza virus infection (8,1). Participants agreed that it is easy to find information about the flu vaccine (7,5, on a scale of 1 to 10), that the available information is clear (7,2), that it is given the deserved prominence in the media (7,2), and that the National Health Service (NHS) provides a quality service in disseminating information about it (7,0). Overall, 80,2 % of the participants considered themselves well informed about the flu vaccine.

Nearly all participants had received at least one dose of the COVID-19 vaccine (97,6 %). No association was found between age or level of education and COVID-19 vaccination status. However, COVID-19 vaccination tends to be less prevalent in participants without income (83,2 %) in comparison to other income levels (ranging from 96,4 % to 100 %) (data not shown in Table 2). Participants were satisfied with the effectiveness of the COVID-19 vaccine (8.0, on a scale of 1 to 10) and agreed that they will continue to take the doses recommended by the Health Authorities (8,1). Most participants agreed that information regarding the COVID-19 vaccine was provided in a clear and explanatory manner (8,1) and were globally satisfied with the information they received about the COVID-19 vaccines and booster doses (7,3). Participants with CRD rated this information lower than undiagnosed participants (6,8 vs 7,5, p = 0,002).

We observed a highly favorable view of vaccines. Vaccine importance to protect others and rigorous testing of vaccines are significantly recognized, particularly among patients with CRD. Factors influencing the observed low flu vaccine coverage rate despite this favorable view might include low risk aversion and significant prevalence of less severe CRD (chronic sinusitis or rhinitis, for example) among the studied population.

Unfavorable perspectives or negative consequences of vaccines were mostly disagreed to by the studied population, in particular by CRD patients. Nonetheless, strengthening public involvement and maintaining trust in vaccination programs is a permanent task facing significant challenges, including elevating the interest of municipalities in health literacy, communicating about health promotion and disease prevention.4,5 Studies have shown that important subsets of the population do not get vaccinated due to poor access to scientific information and the spread of fake news.6,7 Perceptions about the specific necessity of the flu vaccine among the young and healthy and among pregnant women were divided but there was wide agreement that vaccination is crucial during the flu season and that the flu vaccine is effective. There were also favorable opinions regarding the accessibility of information about the flu vaccine. Participants expressed satisfaction with the effectiveness of the COVID-19 vaccine and the accessibility and clarity of information about the COVID-19 vaccine. Most respondents, particularly those with CRD identified the dissemination of more information and clarification about vaccination as a suggestion for improvement. Overall, our study demonstrates that the Portuguese population has a favorable perception of vaccines and the access and clarity of related information, with CRD patients demonstrating added awareness about its importance.