Sample Size Calculation

According to research on residents' anxiety during the COVID-19 period in Zhejiang province, the positive rate of anxiety among residents was 41.41% [25]. The confidence level of the sample size was 95%, while the set α was .05, z_α/2 was 1.96, and the tolerance error δ was 0.04, based on the sample size calculation formula: n=z²_α/2 P (1- p) / δ². The required sample size was calculated to be 583 individuals. Assuming that 20% of the responses would be problematic, the sample size was adjusted to 729 for this study.

Scale Development

Based on interviews with blood donors and a review of relevant literature, we developed the Blood Donation Worry Scale by using the Likert scale method, drawing from the Blood Donation Anxiety Scale designed based on the extended theory of planned behavior [26,27] and the Negative Outcome Expectation Scale [28] in the context of the COVID-19 pandemic. Using the Delphi method, experts in the fields of blood donation, epidemiology, social medicine, and other relevant fields were invited to perform 3 validation modifications, and 10 pilot tests were performed. The scale was finalized after fine-tuning the statements. The scale was divided into 2 parts: the first part was the survey description and informed consent form and the second part was the content of the scale. The content of the scale consisted of basic information and subscales. Basic demographic factors such as sex, age, education level, previous blood donation times, and current COVID-19 infection status were included. The current COVID-19 infection status was divided into 4 categories: uninfected, positive infection, recovered within 7 days since infection, and recovered after more than 7 days since infection. According to the Guidelines for the Prevention and Control of COVID-19 infection in BTSs (edition II) issued by China [29], individuals infected with COVID-19, except for severe and critical cases, can donate blood at 7 days after the last positive result. The subscale had 3 parts: intention to donate blood, blood donation worries regarding COVID-19, and the specific content of blood donation worries regarding COVID-19 summed up in 14 items. The item of “intention to donate blood” was divided into 7 categories: (1) I have never heard of voluntary blood donation; (2) I have heard of voluntary blood donation, but I have not considering blood donation; (3) I am still struggling to donate blood; (4) I have decided not to donate blood; (5) I have decided to donate blood but have not taken any action yet; (6) I have decided to donate blood, but I am currently unable to donate blood due to the requirements of blood donation (such as the interval time after infection); and (7) I have donated blood recently. For convenience in the analysis, the former 4 categories were grouped as “no intention to donate blood or not yet,” and the latter 3 categories were grouped as “intention to donate blood.”

The item of “have you had any worries (hereinafter referred to as blood donation worries regarding COVID-19) about your ability to donate blood after being infected with COVID-19 (or assumed infected)?” Specifically, this refers to the psychological state of refusing to donate blood even if the policy and physical conditions permit to do so (Textbox 1). It also includes the behavior of participating in blood donation but with doubts. In particular, this item assessed the respondents' thoughts or behaviors about their ability to donate blood in the context of the COVID-19 pandemic. Based on the response to this item, respondents were classified as part of the worried group if they answered yes and the non–worried group if they answered no. Further, to understand the specific concerns of these 2 groups about blood donation worries regarding COVID-19, we listed 14 common worries and used a 5-point Likert subscale to assess their specific worries. According to the literature and previous research experience [1,15,16], this 14-item scale was guided by the extended theory of planned behavior and based on the attitude, perceived behavior control, and subjective norms of the theory of planned behavior while also extending the factors of blood donation anxiety and negative outcome expectation. Specifically, item a corresponds to the attitude factor; item l and item i correspond to the perceived behavior control factor; item f, item g, and item h correspond to the subjective norm factor; item n represents the blood donation anxiety factor; and items b, c, d, e, j, k, and m correspond to the negative outcome expectation factor. Reliability and validity analyses were performed on the worry scale with 14 items. The results showed that Cronbach α was .911 and Guttman split-half was 0.879, both of which were above .70, indicating good internal consistency reliability of the scale. The Kaiser-Meyer-Olkin Measure of Sampling Adequacy was 0.927, which was greater than 0.800, indicating a strong correlation between variables and meeting the requirements.

Items a, d, f, and g in both the studies reflected the same essence, but the expression was in the opposite direction in the study during the non–COVID-19 stage. These 4 items were subjected to comparative analysis after corresponding processing by the scoring method. Items b and c were similar in content in both the studies, with the same direction in the expression, and items m and n were exactly the same, facilitating comparative analysis.

Ethics Approval

This study was approved by the regional ethics committee of the Blood Center of Zhejiang Province (approval 2023-021). Each respondent carefully read and filled the informed consent form, which evaluated both the respondent's understanding ability and the screening of research participants. Respondents indicated their understanding of the study and gave their authorization by ticking the agreement box. The informed consent form included the following content: I understand that I can withdraw from this investigation at any time. I understand that the information I provided while participating in this survey will be kept confidential. I understand the purpose and nature of this investigation. I agree that the researcher can use the data collected from this survey for analysis and research. I agree to participate in this investigation.

Data Collection

Using the platform of the Zhejiang Mobile Communication Company, we conducted a stratified random sampling survey among the public according to age. From December 31, 2022, to January 3, 2023, a total of 100,151 invitation text messages were sent to people aged 18-60 years in the Zhejiang province. The text messages contained links to the scales. Each person who successfully completed the scale was rewarded with ¥5 (¥1=US $0.7). On January 4, a total of 1254 scales were collected, with a recovery rate of 1.25%, and all these scales were validated, with an effective rate of 100%, which met the sample size requirements.

Analysis of the Worry-Related Items

Our study identified 14 specific worry items and found that the 4 most worrisome aspects for people were that blood donation will cause temporary weakness (mean 3.21, SEM 1.177), physical condition does not meet the blood donation requirements (mean 2.90, SEM 1.180), the location and working hours of blood donation are not convenient (mean 2.83, SEM 1.046), and my family (friends) will be worried about my participation in blood donation (mean 2.68, SEM 1.118) (Table 3).

Comparison Between the Specific Worry Items During the COVID-19 Pandemic and During the Noninfectious Period in 2022

In this study, the 14 worry items of the respondents were compared with the worry items collected in a previous cross-sectional study conducted by Q Hu (unpublished data, March 2022), which collected data from 1198 participants in Zhejiang to determine people’s basic psychology toward blood donation. A comparison of 8 items (Multimedia Appendix 1) showed that all items were significantly different except for “family (friends) will be unhappy (angry) if I participated in blood donation.” Among them, the extent of worries about the items on blood donation is harmful to health, blood donation will cause temporary weakness, donated blood may be infected with diseases, and family or friends would be worried if I participated in blood donation was significantly higher (all P<.001) than that in March 2022. However, the worries about adverse reactions to blood donation; dissatisfaction with the blood donation experience (whether when I donated blood or what I heard from others, causes me to worry about donating blood); and if I am asked to donate blood or donate blood again, I will feel distressed and anxious were lower than those in March 2022 during the non–COVID-19 pandemic.

Logistic Regression Analysis of Blood Donation Worries Regarding COVID-19

A logistic regression analysis was conducted on the blood donation worries regarding COVID-19 as the dependent variable. As shown in Table 4, the items COVID-19 infection status, worry about adverse reactions to blood donation, family or friends worrying with regard to blood donation, and dissatisfaction with the blood donation experience were the factors influencing blood donation worries regarding COVID-19.

Four Main Worries of the Public Regarding Blood Donation

The 4 main worries of the public regarding blood donation during the COVID-19 pandemic reflected a decline in the perceived behavioral control and subjective norms toward blood donation as well as the negative impact of attitudes toward blood donation.

The first worry of the public regarding blood donation during the COVID-19 pandemic was the effect of the COVID-19 infection status. In particular, if people were infected with COVID-19, they were worried about their physical conditions not meeting the requirements for blood donation (Table 4), indicating that COVID-19 infection had a psychological impact on people, which is consistent with the results of previous studies [31]. It also fits with the perception that people who have experienced infection, in general, perceive a higher risk than those who have not [32]. Compared to those in the nonpandemic stage of COVID-19 in Zhejiang province (Q Hu, unpublished data, March 2022), the 4 items with the highest degree of public worry during the COVID-19 pandemic period were blood donation may lead to infection with diseases, blood donation will cause temporary weakness, blood donation is harmful to health, and worries of family or friends regarding blood donation (Multimedia Appendix 1). The first 3 items were health-related concerns. This reflects that in the context of the COVID-19 outbreak, most of the public's attention was focused on COVID-19 and the perceived threat, which included the perceived susceptibility and the severity of infection. At that time, the public was highly sensitive to how the disease would affect their bodies and whether they would contract the infection, which is consistent with that reported in India, wherein the main reason that people did not donate blood (rate of 55%) was the fear of COVID-19 infection [33]. Other studies in the literature have shown that the higher the perceived threat, the more worry is triggered, which motivates people to adopt self-protective behaviors to control the danger [34-36]. In other words, the motivation to protect oneself from the disease takes over. In this study, during the peak of the COVID-19 pandemic, the number of blood donors decreased sharply. Except for those who were unable to donate blood, such as those infected, we speculate that this decrease was related to self-protective behaviors, that is, people may have wanted to take care and were more willing to avoid behaviors that might be associated with an increased risk of infection.

The second worry of the public, in terms of the overall situation of the specific worries of the public, was that blood donation will cause temporary weakness and that their physical health condition does not meet the blood donation requirements (Table 3). From the perspective of planned behavior theory, these 2 points fall under the category of perceived behavioral control as an influencing factor. Perceived behavioral control refers to obstacles that reflect the past experiences and expectations of the individual. The more resources and opportunities the individual thinks they have and the fewer obstacles they expect, the stronger is the perceived control of the behavior, that is, the degree of control (or mastery) the individual expects to feel when adopting a specific behavior [37]. The results of this study indicated that the public had less confidence in their ability to donate blood during the COVID-19 pandemic and expected that their ability to donate blood would decrease in the future. The COVID-19 pandemic is different from previous emergencies such as 9/11, in which people had high short-term enthusiasm for blood donation. However, the COVID-19 pandemic was different; it was a threat to the health of the whole population and their ability to donate blood, which was reflected in the blood donation behavior and the decline of the public's ability to donate blood and perceived behavior control.

The third worry of the public was that the blood donation site’s location and working hours were inconvenient. We speculated that this was related to the public health initiative to avoid gathering as much as possible owing to the rapid transmission of COVID-19. The distance from blood donation sites or inconvenient opening hours increased the risk of public travel by public transport, which could lead to higher infection rates.

The fourth worry of the public was that family or friends would be worried if they participated in blood donation, thereby reflecting the subjective norm level. Subjective norm refers to the social pressure to adopt a particular behavior, that is, the pressure from significant others or team members to believe that one should or should not perform a particular behavior. In the COVID-19 pandemic environment, as most people were at home at the time, the approval of blood donation by family and friends also became an important factor for respondents to consider. Not only did the public pay more attention to their own health but also their family and friends would influence their views on participation in blood donation and suggest postponing blood donation. These worries and suggestions could be pressurizing and contribute to reduction in blood donation.

This study also shows that worries regarding the harmful effects of blood donation on health during the COVID-19 pandemic were significantly higher than those during the non–COVID-19 pandemic period (Multimedia Appendix 1). These worries reflect the public's basic attitude toward blood donation, thereby creating a negative blood donation behavior. BTSs and the society should guide and correct this negative attitude. Therefore, the COVID-19 pandemic has reduced the public's perceived behavior control ability and subjective norms of blood donation to a certain extent and has had a negative impact on attitudes toward blood donation. However, family or friends would always be worried about blood donation, regardless of whether it was during the prepandemic period or the pandemic period. Worries regarding adverse reactions to blood donation, dissatisfaction with the previous blood donation experience, and anxiety about blood donation were more prevalent in the pre-epidemic period. This suggests that some worries about blood donation will persist, and BTSs should focus on addressing these long-standing worries from the public’s point of view.

Factors Influencing Blood Donation Worries Regarding COVID-19

In addition to COVID-19 status, the factors influencing blood donation worries regarding COVID-19 included worries about the adverse reactions to blood donation, dissatisfaction with the blood donation experience, and worries of family or friends regarding blood donation (Table 4). However, the level of worries for the former 2 items was significantly lower than that during the non–COVID-19 pandemic period (Multimedia Appendix 1). We speculate that this may be because people's concerns were focused on physical health and how to avoid infection in the COVID-19 pandemic stage. At that time, there were still worries about adverse reactions and unsatisfactory experiences with blood donation, but these were not the main worries. However, if the respondent had been infected or if their current health condition made it impossible to participate in blood donation, worries about blood donation itself would appear. Thus, BTSs should focus on improving the blood collection technology and blood donation service, thereby reducing the occurrence of adverse reactions to the blood donated, improving the satisfaction with the blood donation experience, and improving their own service level. Concurrently, it is necessary to continue to follow up on publicizing voluntary blood donation in the society and targeting the families and friends of blood donors. Once worries about the infections have been resolved, the safety of the donation process, the experience, and the support of family and friends are the main concerns.

Impact of the COVID-19 Pandemic on Blood Donation Intention

This study shows that male sex, older age, and more previous blood donations were associated with higher intention to donate blood, which were consistent with previous literature results [38,39]. In particular, previous blood donation experience was significantly correlated with blood donation intention (β=1.599), which verified that past behavior was the best predictor of future behavior [40-42]. This study also investigates the effect of blood donation worries regarding COVID-19 as a mediating factor for blood donation intention. The results indicated that respondents with blood donation worries regarding COVID-19 had a lower intention to donate blood compared to those who clearly stated that they did not have blood donation worries regarding COVID-19. This also confirms that the change in self-protection behavior is closely related to worry and the correlation strength is high [43]. In addition, one of the direct influencing factors of blood donation intention was the attitude that blood donation is harmful to health. The deeper this worry, the lower was the intention to donate blood. Negative attitudes toward blood donation can lead to a decrease in blood donation intention, which should be considered. Similar to that reported in previous studies [44,45], this study also verifies that anxiety about blood donation is a direct influencing factor of blood donation intention, and reducing blood donation anxiety can promote blood donation intention.

Coping Strategy

Given the negative impact of the COVID-19 pandemic on the public's blood donation psychology and behavior, we suggest that BTSs should strengthen their publicity efforts, taking the recovery phase of COVID-19 as an important time point. This involves increasing the introduction of blood collection and supply processes as well as operating norms. BTSs should take efforts to reduce the public's concerns that blood donation may cause temporary physical weakness and infection, address the negative perceptions of blood donation, boost the public's confidence in their ability to donate blood, enhance their perceived behavioral control, alleviate concerns of family and friends to some extent, and improve subjective norms. In the medium and long term, whether the public's blood donation worries regarding COVID-19 will gradually decrease and whether the intention to donate blood will recover to previous levels still needs further observation.

Limitations of This Study

The scale designed in this study has added factors such as COVID-19 and mainly discussed blood donation worries regarding COVID-19 and the influencing factors of blood donation intention. This scale is not exactly the same as the scale used in March 2022 (Q Hu, unpublished data) during the non–COVID-19 pandemic stage. The positive and negative expressions of sentences used in our scale may have caused a certain bias in the respondents' conscious choices. In addition, this study only included the Zhejiang province of China; therefore, the sample has geographical limitations and is not representative of other places.