Table 1 shows that among 6029 respondents, the majority of them were medical students (89.9%), female (71.9%), and single (92.3%). The mean age was 22.9 years old. Most were working or studying at colleges or universities (68.7%), living in the urban (86.1%), and located in the South of Vietnam (64.7%). A larger proportion of respondents (53.9%), most of them were medical students, reported that they had not ever participated in epidemic prevention activities at the community level.

Table 2 reveals the operational readiness capacities of the health system regarding four mentioned criteria. The mean scores of assessed criteria were at a medium level, ranging from 6.3 (the sufficiency of equipment and facilities) to 6.8 (general capacity of health professionals). Significant differences in all criteria were found in two categories, including health system levels and living areas. Within the health system levels category, respondents studying or working at colleges or universities and central-level hospitals reported higher scores than those working at provincial and district levels. Regarding living areas, the capacities of the health system were rated higher by those living in the urban compared to their rural counterparts.

Factors associated with the capacity of the grassroots health system are indicated in Table 3 . Living in rural areas (Coefficient (Coef.) = -0.52, 95% confidence interval (CI) = -0.73; -0.31), working at district level hospitals (Coef. = -0.52, 95%CI = -0.89; -0.14), and living in the South (Coef. = -0.22, 95% CI = -0.37; -0.06) were negatively associated with capacity of health system for all assessed criteria.

This study provides empirical data to elucidate the operational readiness capacities of the grassroots health system in Vietnam. Generally, capacities regarding four assessed criteria were at moderate levels, revealing vulnerability to the risk of epidemic events of the grassroots health system. Moreover, our findings indicate that these capacities in the rural areas, in the South, and at the district level were more likely to be vulnerable compared to their counterparts. Our findings provide useful insights for effective strategies to strengthen the capacity of the grassroots health system in the long term. In the short term, practicing precautionary measures to avoid adding the burden on the health system and mobilizing human resources, as well as medical equipment are all needed to fight against COVID-19 in Vietnam.

The scores rated in our survey were relatively parallel with average scores of the capacity for human resources and health service provision of the Vietnamese health system reported in the IHR SPAR 2018 (60%)[18]. Moreover, in the IHR SPAR 2018, data were recorded at the national level while ours were at the grassroots level. This study, therefore, enriches the understanding of the validity of the IHR SPAR 2018 and makes it contextually appropriate not only at the national level but also at the grassroots level in Vietnam.

Previous studies showed that the lower the IHR SPAR scores, the higher the risk of potential health emergencies, including COVID-19 [21,22]. Given the moderate scores of operational readiness capacities, this study also indicates the necessity to strengthen emergency response capacity in the long term. As a lesson learned from prior natural disasters and epidemics, providing additional personnel with adequate competencies, proper knowledge and skills [23], developing training programs in epidemic preparedness and management of mass casualty incidents [24 ,25], and ensuring an adequate supply of medical equipment for frontlines [26,27] are critical to minimize the risk of health emergencies. In the short term, these findings imply that additional precautionary measures are indispensable for relieving the burden on the grassroots health system. Of note, several simple but effective precautionary measures such as wearing masks, regardless of the presence or absence of symptoms of COVID-19, and washing hands with soap and water frequently have been applied in Vietnam since the early stage of COVID-19.

This study also provides the rationality of prompt and vigorous actions of the Vietnamese Government against COVID-19. Due to the insufficiency of equipment and facilities in addition to limited financial resources, it might not be feasible to implement mass community testing for the SARS-COV-2. In reality, recognizing the vulnerability of the health system, the Vietnamese Government has been responding rapidly to the COVID-19 pandemic since the very first infected case was confirmed on January 22, 2020 [ 28]. A combination of extensive approaches encompasses immediate quarantining infected people and their direct contacts, lockdown areas nearby their residential places, contact tracing, and keeping indirect connections under surveillance. Besides, temperature screening at arrival gates in the airports, at large buildings, and at shopping malls had been performed. School closures and cancellations of festivals, events, and other gathering activities have also been implemented. To minimize imported cases, Vietnam has also deployed rigorous border control measures, including visa entry halting, mandatory health declaration, and enforcement of 14-day quarantine for all incoming travelers to Vietnam [19,29]. When there were more than 200 confirmed cases, a 14-day social distancing requirement had been applied in the entire nation since April 1, 2020. Within the context of Vietnam, these strategies were considered necessary to support the endurance of the fragile health system.

Upon analysis, the operational readiness capacities of the health system in rural regions, in the South, and at the district level were more likely to be limited compared to their counterparts. The disparities among regions in Vietnam have been relatively similar to findings in China [27] and in Ethiopia [30]. This finding suggests that decision-makers should consider a mechanism for managing limited-resources allocation and mobilization among regions as well as a strategy to engage communities in improving locally responsive health care [31]. At the time of writing this paper, the entire Vietnamese population regardless of their socio-economic status, including soldiers, businessmen, scholars, and students are currently support health care workers in the battle against COVID-19. There are many military buildings, university facilities, and dormitories that have been requisitioned as quarantine camps and many temporary hospitals have been rapidly built to support the insufficiency of health care facilities.

There are several implications drawn from this study. First, given moderate scores of operational readiness capacities, strategies to strengthen the capacity of the grassroots health system such as improve the quality and quantity of health care professionals, administrative and logistics staffs, developing training programs, and ensuring an adequate supply of medical equipment are needed in the long term. Second, in the short term, practicing precautionary measures, planning of rapid coordinated responses with community engagement, and mobilizing human resources and medical equipment to relieve the burden on the grassroots health system are necessary to control COVID-19 in Vietnam successfully.

The strength of this study is conducting on large sample size and coverage from the North to the South of Vietnam. This is considered as a condition to enhance the generalizability of study findings. However, this study also contains several limitations. First, we recruited respondents who were referred online rather than randomly selected from a nationally representative sample frame. In addition, the cross-sectional study design is unable to identify the cause-effect relationship between dependent variables and independent ones. Also, the use of self-administration questionnaires did not allowed researchers to explain unclear terms to respondents. Finally, self-reporting data may cause recall bias.

According to empirical data, this study reveals the vulnerability of the grassroots health system in Vietnam and provides the rationality of prompt and vigorous actions of the Vietnamese Government against COVID-19. Findings also offer useful insights for effective strategies to strengthen the grassroots health system in the long term. In the short term, practicing precautionary measures and mobilizing human resources, as well as medical equipment, are necessary for successful COVID-19 containment in Vietnam.