COVID-19 pandemic has disrupted healthcare systems worldwide, causing the postponement or cancellation of millions of elective surgeries. It is essential for hepatopancreatobiliary (HPB) surgeons to well understand the perioperative risk and management of HPB surgery during the COVID-19 pandemic, including the impact of preoperative COVID-19 infection and timing of surgery, the impact of COVID-19 infection on postoperative mortality, the postoperative pulmonary complications in patients with perioperative COVID-19 infection, and the postoperative complications without pulmonary involvement. Perioperative COVID-19 infection increases the risk of postoperative mortality and pulmonary complications in patients undergoing abdominal surgery. Furthermore, in some regions, the COVID-19 vaccine's availability is still limited, leading to an increase in the number of cases and potential medical collapse, which could hinder the improvement of HPB postoperative mortality rates. The timing of surgery for COVID-19 positive patients should be carefully considered, balancing the potential risks of delay with the risks of surgery during the infection.

Japan's responses to COVID-19 have been conducted based on the Act on the Prevention of Infectious Diseases and Medical Care for Patients with Infectious Diseases (the Infectious Diseases Control Law) and the Act on Special Measures against Novel Influenza, etc. (the Act on Special Measures), as COVID-19 is classified as the category of "the Novel Influenza etc." under the Infectious Diseases Control Law. The government's Novel Coronavirus Response Headquarters decided to reclassify COVID-19 as a Category V infectious disease under the Infectious Diseases Control Law in May 2023 since the disease has become less lethal. Accordingly, the countermeasures such as surveillance and medical care are going to be reviewed, and COVID-19 prevention actions will depend on personal choices (Prior to the review in May, mask usage will be changed from 13 March). However, this does not mean that infection control measures are no longer necessary; it is recommended that such measures be taken in certain settings in order to prevent the elderly and those who at a high risk of severe illness from being infected, even after the disease is classified as Category V.

In Japan, there has been a discussion of the potential reclassification of the novel coronavirus infectious disease 2019 (COVID-19) as an infectious disease under the Act on the Prevention of Infectious Diseases and Medical Care for Patients with Infectious Diseases (the Infectious Diseases Control Law), beginning in late 2022. To make an informed decision, the societal impact of COVID-19 needs to be carefully considered to ensure that any reclassification does not negatively impact healthcare or society as a whole. The disease burden of COVID-19 remains considerable and is likely to persist for an extended period of time. Consequently, numerous special measures have been taken in the healthcare system to cope with COVID-19. Several of these measures must be implemented. Thus, the healthcare system needs to be strengthened in the future. This will result in adequate prevention, preparation, and a response to future pandemics.

The outbreak of the novel coronavirus infection caused worldwide confusion. The problem with this infection is that it causes severe illness in some patients, resulting in a high rate of death if appropriate treatment is not given. If patients with severe illness that requires treatment are appropriately identified, treatment can be focused on these patients. However, in the early days of the COVID-19 outbreak, the inability to predict and diagnose the disease led to hospitals being overwhelmed. Therefore, various methods for the diagnosis of severe disease were developed early on, and various methods are still being investigated to predict high-risk patients. The currently available prediction methods are divided into those that predict the onset of severe disease and those used to determine the severity of the disease. Specifically, the main methods include genetic factors, serum humoral factors, laboratory tests, and diagnostic imaging. Since each of these factors has different features, using them in combination is likely to be advantageous.

The National Center for Global Health and Medicine plays a central role in the treatment and research of infectious diseases in Japan. It has conducted various research and development activities on drugs to treat coronavirus disease 2019 (COVID-19) with clinical questions as starting points. Clinical trials are essential in developing new treatment modalities, but we have noticed some characteristic difficulties in clinical trials on emerging and re-emerging infectious diseases. For example, since there is no standard of care when an emerging infectious disease starts to spread, establishing an appropriate control group is complicated, and many things are hurried at the start of trials. This means there is little time to arrange a placebo, and conducting blinded, randomized, controlled trials has been difficult. Another issue characteristic of infectious disease has been that progress in enrolling subjects is affected by the spread of the disease. It was also a struggle to select institutions that provide medical care on the front lines of infectious disease and conduct clinical trials regularly. To start multicenter clinical trials expeditiously, a regulated and structured network is thus considered necessary. From the perspective of implementation, it is preferable to conduct decentralized clinical trials (DCTs) that do not depend on people coming to the medical institution, while from the perspective of preventing infections during the spread of COVID-19, wide adoption of eConsent is desirable. Based on the experience of COVID-19, new measures must be taken to prepare for emerging and re-emerging infectious diseases in the future.

Since Cambodia has been recognized as one of the low- and middle-income countries with a successful COVID-19 vaccine program, its program approaches were reviewed based mainly on press articles and announcements from the Ministry of Health. From the beginning, the government's proactive approach to securing vaccines and its flexibility prior to WHO Emergency Use Listing (EUL) contributed greatly to the success of the program. Vaccines were provided by COVAX and other countries, but more than half of the vaccines secured were Chinese vaccines purchased with government funds. The rollout of the vaccine has also been flexible, moving from a strategy of prioritizing risk groups and essential workers to one of expanding the campaign from population centers to rural areas, as well as gradually expanding the target age group, eventually targeting the population age 3 and older. As a result of this high level of commitment by the government and its flexible response, Cambodia has achieved 95% primary series coverage of the entire population, including those not eligible for vaccination. Although the sixth booster is now being administered in Cambodia and vaccination every six months was recommended, several challenges might be anticipated in continuing this program, including the lack of clear global guidance on how to sustain and modify the COVID-19 immunization program and vaccine fatigue after COVID-19 outbreaks have been controlled. How these challenges are overcome and how the COVID-19 vaccine program remains need to be carefully observed into the future.

The coronavirus disease 2019 (COVID-19) pandemic has affected the world for over 3 years. Treatment options have improved substantially during this period, including antiviral drugs, antibody drugs, immune-based agents, and vaccination. While these improvements have reduced mortality rates in patients with COVID-19, some patients still develop severe illness. In this review, we aimed to provide an overview of treatments for patients with severe COVID-19 from study reports and clinical experience. We discussed the treatments from two perspectives: respiratory care and drug treatments. In the respiratory care section, we discussed the usefulness of high-flow nasal cannula therapy and non-invasive ventilation as an alternative to invasive ventilation. In the drug treatments section, we focused on three classes for severe COVID-19 treatment: antiviral drugs, immune-based agents, and anticoagulation therapy. We did not discuss antibody drugs and vaccination, as they are not used for severe COVID-19 treatment.

The symptoms that persist after an acute coronavirus disease 2019 (COVID-19) are referred to as post-COVID conditions. Although the cause of post-COVID conditions remains unclear, the host immune response to SARS-CoV-2 may be involved. Hence, we aimed to investigate the effect of serum antibody titers against SARS-CoV-2 on the development of post-COVID conditions. We conducted a retrospective observational study of COVID-19-recovered individuals who attended the clinic at the National Center for Global Health and Medicine between January 2020 and April 2021. Serum SARS-CoV-2 anti-spike antibody titers were measured and a questionnaire survey was used to collect information on the presence of post-COVID conditions and demographic characteristics of the participants. Participants were then divided into two groups: high peak antibody titer group [≥ 0.759 OD450 value], and low peak antibody titer group [< 0.759 OD450 value] and compared their frequency of post-COVID conditions. Of 526 individuals attending the clinic, 457 (86.9%) responded to the questionnaire. We analyzed the data of 227 (49.7%) participants with measurements of serum antibody titers during the peak period. The incidence of depressed mood was significantly higher in the group with higher antibody titers (odds ratio: 2.34, 95% CI: 1.17–4.67, p = 0.016). There was no significant difference in the frequency of the remaining symptoms between the two groups. Among post-COVID conditions, the depressed mood was more frequent in the group with high serum antibody titers which suggests a difference in pathogenesis between depressive mood and other post-COVID conditions that requires further investigation.

On December 7, 2022, China's National Health Commission issued the Ten New Covid Rules lifting the dynamic zero-COVID policy. In the interim, vaccination campaigns continue to be promoted. We assessed the potential impacts on the status, perceptions, and attitudes toward COVID-19 vaccines via an online self-administered questionnaire. Among 1,170 participants, 1,142 (97.6%) participants were vaccinated against COVID-19, and 51.8% (591/1,142) have already received the booster. More than half of the participants who were vaccinated were ages 31 to 50 (51.8%). Participants believed the following strategies could improve the vaccination rate: timely feedback of the vaccination data (such as safety, efficacy, and other issues of public concern) from authoritative media (95.6%), increasing the number of vaccination sites and availability of vaccines and using more convenient methods of making appointment (95.2%), recommendations from friends and relatives (94.8%), and presenting the qualifications of the staff performing vaccination (89.1%). More measures, including targeted measures for different age groups and timely feedback on the vaccination data including safety and efficacy from authoritative media, are likely to help improve vaccination rates.

The clinical trial industry has encountered challenging circumstances in which the increasing number of trials outpaces the number of trial specialists. For instance, there has been an unprecedented demand for clinical trials following the Covid-19 pandemic, which has worsened the global shortage of qualified personnel. It is therefore imperative to produce more qualified clinical trial professionals. An adaptive and collaborative training model was implemented by the National Center for Global Health and Medicine through the Department of International Trials. This aimed at building capacity among health workers in developing countries and providing them with the skills to be able to conduct all phases of the clinical trial from protocol design to publication of results. It also seeks to foster collaboration and partnership between local health workers and international experts. Since 2016, we have implemented a Japan-led training program, and since 2020, the COVID-19 pandemic has ushered in a shift from a single Train-the-trainer model (ToT) to a mixed model, the Evolving Partnership Training (ePT). In this model, we applied four different methods: train-the-trainer, needs-oriented training, open symposiums, and advanced learning. The total number of training participants increased exponentially from a total of 41 between 2016–2020 to 2,810 in 2021. Our experience has proven that despite the constraint of the pandemic, the ePT is a viable approach compared to a single method for providing quality training and increasing the number of participants.

During the COVID-19 pandemic, the incidence of eating disorders (ED) has increased not only in Japan but also worldwide. This online survey for pediatricians showed that caregivers tend to visit specific pediatric institutions or child psychiatry departments when children under junior high school age develop eating disorders. There are few pediatric institutions regarding treatment acceptance for children with ED. Of the 34 respondents, 16 (47.1%) answered that the number of visits for children with eating disorders had "stayed the same", one answered it had "decreased" and 17 (50.0%) answered it had "increased" or "increased very much". In addition, 28 of the 34 respondents (82.3%) experienced difficulties with psychotherapy for children with ED. For treating children with ED, pediatricians usually conducted physical examination and have some clinical burden. ED are increasing in the COVID-19 pandemic. Because children with severe ED need to be hospitalized, child and adolescent psychiatric wards are overcrowded and some children with other mental disorders can't be admitted.