Several surveys in the general population have shown that the frequency of adverse events of COVID-19 vaccine, such as fever and fatigue, increased after the second dose compared with the first dose [4, 12]. However, we found that the incidence of fever after the first dose in patients with cancer was higher than that in a previous report and was almost the same as that of the second vaccination. Although the individual clinical course of the respondents is unknown because of the anonymous questionnaire used in this study, factors other than vaccine-related adverse events, such as fever with febrile neutropenia after chemotherapy, might be involved. It is difficult to distinguish between these factors that lead to fever after vaccination; since febrile neutropenia necessitates urgent intervention, patients with cancer need to know what to do if they have a fever after receiving the COVID-19 vaccination.

COVID-19 vaccination is recommended for patients with cancer because of the high risk of mortality and the severity associated with a compromised immune response during chemotherapy [7, 8]. A systematic review and meta-analysis reported that female sex and chemotherapy were significant factors associated with COVID-19 vaccination hesitancy in patients with cancer [9]. However, most of the respondents in this study had received two or more doses of the COVID-19 vaccine at the time of their responses, demonstrating a vaccination rate higher than the overall vaccination rate in Japan [13]. Over half of the respondents acknowledged the infection prevention and severity mitigation effects of COVID-19 vaccination, leading them to believe in the vaccine’s efficacy and receive it. Additionally, 41.7% of the respondents cited their “primary care physician” as the consultation source, suggesting that communication with physicians might have influenced their decision to be vaccinated.

Regarding the effectiveness of the COVID-19 vaccination, some respondents indicated a lack of correct understanding of the low response rates for herd immunity (15%) and a misunderstanding of the potential cause of COVID-19 post-vaccination (25%). These findings suggest that the respondents did not understand the efficacy of COVID-19 vaccination in patients with cancer. Continuous dissemination of information regarding the utility of COVID-19 vaccination in patients with cancer is crucial.

Even after vaccination, it is well known that people continue to have some anxiety and concern about the vaccine [14]. This survey also confirmed that 80% of the respondents had anxiety or concerns about COVID-19 vaccination. Regarding the timing of COVID-19 vaccination that showed the highest response as a concern in this study and other reports [15], the Japanese Society of Clinical Oncology recommends the time period when it is better to avoid COVID-19 vaccination [8]. Considering the latest domestic and international evidence, information regarding vaccination timing is deemed beneficial for endorsing the COVID-19 vaccination. Furthermore, approximately 20–40% of the respondents in this study expressed concerns about the incidence of adverse events, unique adverse events, and the safety of the COVID-19 vaccine. Given that concerns about vaccine-related adverse events can be a deterrent to vaccination [16], providing healthcare professionals with information on adverse events is crucial. Compared with other survey reports [4, 12, 17], this survey found no higher incidence of adverse events or unique adverse events regardless of the number of COVID-19 vaccine doses administered, except for a tendency toward more frequent fevers after the first dose. Additionally, this study has identified concerns of patients with cancer regarding COVID-19 vaccine interactions with current medications, and post-vaccination fever in relation to COVID-19 vaccination. Generally, while antipyretics are the first choice for fever management after vaccination, fever following chemotherapy may require appropriate intervention, and the approach may vary. However, our institution lacks guidelines pertaining to fever management. Additionally, although there are risks such as bleeding at the administration site due to antithrombotic agents, there are no explicit recommendations regarding interactions with concomitant medications. Patients undergo vaccination based on the discretion of their attending physicians. To potentially enhance vaccination rates, it may be necessary to establish institutional regulations concerning fever management and interactions between the vaccine and current medicines.

Additionally, there was no difference in the occurrence of adverse events related to COVID-19 vaccination based on the presence or absence of chemotherapy [18]. While many uncertainties remain regarding the long-term safety of COVID-19 vaccination, these findings suggest that patients with cancer can safely receive the vaccine, similar to healthy individuals. Communicating this lack of significant differences in adverse reactions between patients with cancer and the general population can be valuable in allaying concerns. Furthermore, this survey obtained responses citing the severity of adverse events and health damage as reasons for interrupting COVID-19 vaccination. For patients with cancer, it is necessary to assess the feasibility of continuing COVID-19 vaccination from a medical and pharmaceutical perspective, along with implementing interventions, such as proposing medications for symptom relief, to enhance vaccination rates.

Prospective vaccine recipients gather and evaluate information from various sources to address their anxieties and concerns. Telephone interview surveys showed that physicians (77.6%) and federal agencies (50.5%) were highly trusted sources of information on the COVID-19 vaccine, whereas family members (25.9%) and social media (3.8%) were deemed less reliable [19]. People relying on family/friends, faith-based organizations, or social media for healthcare information tend to be hesitant about getting vaccinated [20]. However, even with these information sources considered to be unreliable, our study indicated a high percentage of respondents who utilize “family/acquaintance” and “social networking service” as the source of consultation and information. Conversely, workplaces/schools, LINE (a communication tool like WhatsApp and iMessage highly popular in Japan), and social media sources have encouraged citizens to receive the COVID-19 vaccine [21]. Although the impact of information sources on vaccination intention was not thoroughly examined in this study, it is plausible that consultations with family/friends and the use of social media could have contributed to the high COVID-19 vaccination rates. Continuous research is essential to understand the influence of various information sources on patients with cancer who intend to receive the COVID-19 vaccine.

Consultation with “primary care physicians” was the most common response in this study. This underscores the significance of primary care physicians for patients with cancer in making decisions regarding vaccination feasibility, considering the impact on cancer treatment, vaccination schedules, and existing health conditions. Notably, only one respondent mentioned pharmacists in the survey, indicating a perception of no involvement of pharmacy/hospital pharmacists compared to other healthcare professionals, making them less utilized as consultation channels, possibly because of limited communication opportunities compared to other professions. Particularly in our institution, pharmacist’s interventions for the patients with cancer are primarily focused on the initial and second treatments, with limited opportunities for sustained interventions. Consequently, there are few occasions for pharmacists to engage in communication with the patients with cancer, potentially resulting in lower contact with pharmacists compared to other healthcare professionals. In addition, the low response rate of 42.0% in this study can be attributed to the scarcity of communication opportunities with pharmacists, along with the possibility that some elderly individuals are less proficient in operating tablet devices such as smartphones. Consultations with primary care physicians may have resolved patient’s concerns about COVID-19 vaccination, making consultations with other healthcare professionals unnecessary. However, some respondents in this study still harbored concerns about the COVID-19 vaccination, indicating that unresolved anxieties and worries might persist despite consulting primary care physicians.

In this survey, “hospital pharmacist” was among the easiest to approach, following primary care physicians and nurses. This could be attributed to the trust established through medication counseling and adverse event monitoring during outpatient chemotherapy. With the promotion of designated pharmacies and advanced pharmaceutical management functions, pharmacists are expected to build better relationships with patients with cancer, enhancing the ease of consultation. Pharmacists with an established trust could potentially address the unresolved concerns of patients with cancer, proving invaluable for the continued promotion of COVID-19 vaccination. Since utilization of our hospital as a consultation point is limited, we believe that fostering a trustful relationship with patients with cancer is crucial. This can be achieved by pharmacists conducting sustained interventions and increasing opportunities for communication with cancer patients. A detailed exploration of patient anxieties regarding the COVID-19 vaccine and assessment of pharmacist interventions is crucial for future research.

The limitation of this study may impose difficulty in generalizing our findings and conclusions. The survey was conducted within a single hospital, and the sample size was small. Additionally, there is a significant bias towards cancer types (shown in an Additional file 2), and the participants in this survey may not fully represent the entirety of patients with cancer. Moreover, we did not confirm the treatment regimens and the timing of chemotherapy of patients with cancer. Therefore, the effects of these factors on the purpose of this study could not be evaluated. Although definitive conclusions are challenging, valuable insights were gained to consider the necessary interventions to foster the ongoing acceptance of COVID-19 vaccine administration among patients with cancer.