A total of 2742 travelers agreed to participate in this survey, resulting in an effective response rate of 96%.

Sociodemographic characteristics of participants

Table 1 summarizes the socio-demographic characteristics of the participants. The median age was 36 (28–46) years. The majority of respondents were 30–44 years old (42.8%), male (63.1%), married (54.4%), and Protestant (46.4%). 39.8% had completed formal secondary education. More than half (59.5%) traveled by vehicle.

Table 1 Sociodemographic characteristics of participants

Work was the most frequently cited reason for travel in Kinshasa, Ndjili airport (31%) and Ngobila beach (28%), while business was the main reason for travel in other survey sites, Boma (36%), Lufu (52%), Moanda (33%) and Kananga (33%) (Additional file 2).

Perceptions, attitudes, and practices towards the COVID-19 vaccine

Table 2 shows that 61.9% of the participants indicated that the COVID-19 vaccine can protect against re-infection with the disease. 43% of respondents thought that mass vaccination of the population can provide indirect protection for non-vaccinated people, and 38.9% believed that a single dose of COVID-19 vaccine is sufficient to acquire immunity against the disease. 45.4% of individuals responded that vaccinating travelers at PoEs could eliminate COVID-19. A not insignificant proportion of the participants perceived the vaccine to have side effects (54.9%) and to be unsuitable for anyone, regardless of age (42.1%). A total of 45.4% and 42.1% of the participants, respectively, indicated uncertainty regarding the administration of the COVID-19 vaccine to individuals with known allergies or chronic diseases.

Table 2 Perceptions of respondents towards COVID-19 vaccine

Table 3 demonstrates that 60.5% of the participants admitted to be concerned about COVID-19. Approximately 69% of respondents agreed with government-approved vaccines, while 54% agreed with vaccine safety and effectiveness. 63.2% of travelers agreed to vaccination (revaccination) at the PoE.

Table 3 Attitudes of respondents towards COVID-19 vaccine

The majority of participants reported not washing their hands frequently (58.5%), not wearing masks (88.5%) and not keeping social distance (94.7%) in closed public places, not covering their mouths and noses when coughing or sneezing (75.5%), and not being tested for COVID-19 in the presence of signs suggestive of the disease (83%) (Table 4).

Table 4 Practices of respondents towards COVID-19Comparison of sociodemographic characteristics, perceptions, attitudes, and practices according to vaccination status

Table 5 displays comparisons between vaccinated and unvaccinated groups according to sociodemographic characteristics, perceptions, attitudes, and practices. Overall, 1474 (54%) of the 2742 participants included in the survey had received at least one dose of a COVID-19 vaccine. The median age in the vaccinated group, 38 (30–49) years, was significantly higher than in the non-vaccinated group, 34 (27–43) years. The proportion of vaccinated individuals was higher among those aged 30 and older, with a secondary or high education level, and who were married. Unvaccinated participants were more likely to be unemployed, and to adhere to other religious beliefs, compared with vaccinated participants. They were also more likely to travel by vehicle and bicycle or on foot. In addition, respondents who had been vaccinated were more likely to have good perceptions, positive attitudes, and good practices towards COVID-19 vaccination compared with those who had not been vaccinated.

Table 5 Comparison of sociodemographic characteristics, perceptions, attitudes, and practices of participants according to vaccination status

Among vaccinated travelers, 42.3% had received a Johnson & Johnson vaccine, followed by Pfizer (14.8%), Moderna (12.9%) and AstraZeneca (10.4%). 17.4% could not recall which vaccine they had received (Additional file 3). With the exception of the Johnson & Johnson vaccine (93.7% single dose), less than 70% of vaccinated participants had received two doses of each vaccine. Six out of ten vaccinated respondents who could not recall the type of vaccine had received a single dose (Additional file 4). Furthermore, the main reasons cited by travelers for vaccinating against COVID-19 were disease prevention (49.3%), ease of travel (19.7%), and disease awareness (15.0%) (Additional file 5). Healthcare workers (HCWs) were more likely to be vaccinated because of disease prevention (71.3%), awareness (23.0%), and a history of COVID-19 infection (4.9%), while traders cited ease of travel (18.4%) and fear of disease (4.0%) (Additional file 6). In addition, 10% of participants admitted to having contracted COVID-19 despite vaccination (Additional file 7).

Among individuals who have not received the vaccination, the most common reason for not doing so was fear of side effects (37.1%). A total of 29.3% of unvaccinated individuals indicated that they believed the vaccine to be unsafe and ineffective, while 16.2% stated that they did not believe the disease to be real (Additional file 8). Furthermore, 57% of respondents did not agree to get vaccinated at the PoE surveyed because of the risk of travel disruption, while 38% said the site was unsuitable for vaccination (Additional file 9).

Factors associated with COVID-19 vaccination status

In univariate logistic regression analysis, it was found that age, education, marital status, religion, occupation, means of transport, perceptions, attitudes, and practices were statistically significantly associated with vaccination status. In the final multivariable logistic regression analysis (Table 6), respondents in the age groups of 18 to 29 years (AOR: 1.85, 95% CI: 1.16-3.00), 30 to 44 years (AOR: 1.90, 95% CI: 1.23–2.99), and 45 to 59 years (AOR: 1.78, 95% CI: 1.14–2.83) were less likely to get the COVID-19 vaccine, compared to those aged 60 years or older. Single individuals were more likely to be unvaccinated than married individuals (AOR: 1.78, 95% CI: 1.45–2.18). Civil servants (AOR: 2.61, 95% CI: 1.47–4.81), traders (AOR: 2.20, 95% CI: 1.27-4.00), and other professional categories (AOR: 2.60, 95% CI: 1.50–4.70), as well as the unemployed (AOR: 2.55, 95% CI: 1.45–4.65) were found to be less likely vaccinated than healthcare workers. Respondents who travelled by foot or bicycle (AOR: 26.62, 95% CI: 10.59–77.21), vehicle (AOR: 11.55, 95% CI: 8.19–16.60), and boat (AOR: 8.06, 95% CI: 5.67–11.65) were more likely to be in unvaccinated group than those who flew. People with poor perceptions towards COVID-19 vaccine were more hesitant to get vaccinated than those with good perceptions (AOR: 3.42, 95% CI: 2.87–4.09).

Table 6 Logistic regression analysis of factors affecting COVID-19 vaccination status among travelers