Methicillin-resistant Staphylococcus aureus (MRSA) has spread worldwide since the 1960s and is still one of the most important causative pathogens of health care-associated and community-acquired infections about 60 years later. Since 2000, the disease burden of MRSA due to the practice of multifaceted intervention has been decreasing year by year compared to multidrug-resistant Gram-negative bacteria, although it varies slightly depending on the infection control and regional characteristics of epidemic clones. However, the ratio of MRSA to S. aureus in Japan has stopped declining at around 50%, and the reasons for this are an increase in the spread of community-acquired MRSA in the hospital and an increase in the number of hospital-acquired MRSA carriers in the community, making it difficult for each medical institution to complete infection control against MRSA alone. MRSA infections range from asymptomatic carriers to soft skin tissue infections to fatal invasive infections. The basics of MRSA infection control are identification of infection sources and blocking of infection routes (standard precaution and contact precaution), appropriate use of antimicrobials (including antibody MRSA drugs), and appropriate support/intervention for high-risk patients. It is important to grasp the trends in the entire region and cooperate with each other to implement infection control measures.

For a pregnant woman with a confirmed case of COVID-19, there is concern about a perinatal outcome. Two and a half years since the onset of the pandemic, many reports including pregnancy complications and neonatal outcomes have been accumulated. In 2021, several national surveillances (from the UK, Sweden, and Spain) have been published. These reports indicated that the positive rates of polymerase chain reaction (PCR) tests in infants born to mothers tested positive for COVID-19 are supposed to be 1.6%-5%. There is no evidence for intrauterine placental transmissions of COVID-19 to fetuses. Recently, multiple systematic reviews evaluating the impact of COVID-19 on maternal and newborn health have been reported. These reports suggested that pregnant women with COVID-19 have a higher risk of preeclampsia (OR 1.3-1.6) and preterm birth (OR 1.6-1.9) compared with those with no SARS-CoV-2 infection during pregnancy.

Multisystem inflammatory syndrome in children (MIS-C) is an immune-mediated condition occurring weeks after a COVID-19 infection. Multisystem inflammatory syndrome in neonates (MIS-N) presents symptoms consistent with MIS-C related to maternal SARS-CoV-2. It is speculated that transplacental antibodies cause MIS-N. In neonatal patients born to mothers with a history of COVID-19, MIS-N is considered in the differential diagnosis to explain unusual signs of multisystem inflammation.

The current evidence suggests that the risk of newborns acquiring infection during birth hospitalization is low when precautions are consistently taken. Moreover, a viable infectious virus has not been detected yet in breast milk. Recently, it has been recommended globally to avoid separating the mother from the baby. However, in most Japanese hospitals, newborns are still separated from their infected mothers. There is some concern about the negative impact induced by these strict precautions.

The global outbreak of COVID-19 has transformed the environment surrounding the practice of respiratory infectious diseases: emerging evidence on COVID-19 is being built up around the world daily, and public interest has increased to an unprecedented level. As a result of the widespread adoption of hand hygiene and social distance by the public, the number of cases of influenza and other non-COVID-19 infectious diseases has decreased dramatically.

Regarding COVID-19, severe cases have occurred mainly among patients with underlying medical conditions and the elderly, straining medical care, but the vaccine has been effective in suppressing infection in vaccinated cases. On the other hand, the mutant strains have also increased the risk of infectivity, and in the fifth wave in Japan, infection spread mainly among young people who had not been vaccinated. Since the virus will continue to mutate and there will be a certain number of non-vaccinated individuals, SARS-CoV-2 infection will not be completely eradicated in the future. Therefore, we must always consider COVID-19 as one of the differential diseases for the numerous respiratory infections in the post-COVID-19 era. Particular attention should be paid to the possibility of COVID-19 pneumonia in the initial diagnosis of a patient with interstitial pneumonia. On the other hand, even in the disaster caused by COVID-19, the number of patients with aspiration pneumonia has not shown a downward trend because of a super-aging society, and this is one of the major issues in respiratory care in Japan.

The purpose of this study is to clarify the factors that influence the behavior of dentists and dental hygienists working in dental clinics related to occupational infection control. Questionnaires were distributed to 3, 443 dental clinics in Hyogo and Yamagata prefectures from September to November 2020, and 855 copies (24.8% response rate) were completed. The result showed that the person's knowledge of infection control had the greatest impact on actions related to occupational infection control. The number of workshop participations in the past two years affected the possession of knowledge and the opportunities to acquire knowledge. Furthermore, it was suggested that the older the age, the lower the knowledge. The experience of occupational exposure was not associated with behaviors related to occupational infection control. As for the effect of environmental factors on their workplace, the installation of washer-disinfector (W/D) as facility equipment had an effect on behavior through knowledge acquisition. However, the influence of other environmental factors such as the size of the facility and several external factors was not found. This study showed that the possession of knowledge was the most effective factor in influencing behavior related to occupational infection control. Moreover, the opportunities to acquire knowledge can be reflected in the current behavior related to occupational infection control not only through basic education but also by participating in the recent workshops and actively obtaining necessary information from various sources.

BNT162b2 mRNA COVID-19 vaccine has been shown to be effective in preventing onset of disease, but these effects have been reported to decline over time. On the other hand, postvaccination antibody titers have been suggested to correlate with infection prevention efficacy, but there are few reports on factors affecting antibody titers long after vaccination. We tested staff for antibodies against SARS-CoV-2 spike-protein receptor-binding domain after receipt of the second dose of vaccine. Also, we conducted a retrospective cohort study on factors affecting antibody titer after more than 6 months. Staff who were known to have had COVID-19 in the past and those who were not able to collect information by questionnaire were excluded. In this study, we found that the antibody titer decreased significantly when more than 6 months had passed since receipt of the second dose of vaccine. In the univariate analysis, age, gender, and use of hypertensive agents were found to be factors affecting antibody titer in health-care workers who had been vaccinated for more than 6 months. In addition, age was found to be a factor affecting antibody titer in the multivariate logistic regression analysis. Age is a factor affecting antibody titer not only in Japan but also in overseas reports. The results of this study showed that the decrease in vaccine antibody titer over time was more pronounced in the elderly than in the young, when more than 6 months had elapsed since the second dose of vaccine, suggesting that the vaccine's effectiveness in preventing infection is more susceptible to temporal effects in the elderly.

We conducted a questionnaire survey on the status of infection control organizations, measures taken, and personal protective equipment (PPE) worn during various types of care and medical procedures at psychiatric hospitals and nursing homes, geriatric health-care facilities, and special nursing homes in the metropolitan area of Tokyo (Tokyo, Kanagawa, Chiba, and Saitama) during the COVID-19 (latest coronavirus infection) pandemic. The common denominator among all facilities was that infection control committees were established (establishment rate: 86.7%), but there were no infection control specialists (assignment rate: 9.1%). The rate of information sharing with neighboring medical institutions was 50.0% (24/48) in psychiatric hospitals, 59.5% (22/37) in geriatric hospitals, and 42.4% (14/33) in special care facilities.

While the rate of mask usage was 100% at all facilities, the status of wearing other PPE appeared to deviate from standard precautions. Many hospitals and facilities chose PPE that appeared to be an inadequate measure for COVID-19, especially during medical procedures involving aerosols and bathing assistance at nursing homes. In light of these circumstances, it is necessary to incorporate the opinions of infection control experts when preparing an infection control manual tailored to the actual conditions of one's facility and establish a system that allows regional cooperation with neighboring medical institutions. Moreover, cooperation with outside infection control experts is considered an urgent task.