Three years have passed since the outbreak of coronavirus disease 2019 (COVID-19) in Wuhan, China. The pandemic rapidly spread worldwide, especially through Europe and the Americas.

The Journal of Disaster Research (JDR) edited its “Special Issue on COVID-19 and Historical Pandemics, Part 1 and Part 2” at the end of 2020 and 2021, and their electronic versions were published in January 2021 (JDR Vol.16, No.1, pp. 1-117) and January 2022 (JDR Vol.17, No.1, pp. 1-158), respectively.

However, the pandemic is still continued and not yet eradicated. The cumulative number of cases of COVID-19 worldwide, as released in the World Health Organization (WHO) Weekly Epidemiological Update was 260 million as of December 2021. We therefore planned for the publication of this Special Issue Part 3 and called for papers.

This Special Issue Part 3 includes nine manuscripts, which deal from various fields related to COVID-19, such as including vaccine rollout program, the role of social media, problems in school education, therapeutic agents, virology, and general epidemiology. This suggests that the COVID-19 pandemic is a complicated disaster.

In December 2022, the global number of cumulative cases have increased to 940 million, almost one-tenth of the world’s population, although this number includes many asymptomatic infections. On the contrary, the number of new COVID-19 cases has slowed of mildness in the American and European countries in the year 2022, yet there has been a conspicuous increase in newly reported cases in Asia, especially in the Republic of Korea and Japan. Although the cases from African countries have still continued to report fewer numbers of cases than the number from other areas, However, there is still some possibility of that this is because of a lower number of medicinal tests, such as polymerase chain reaction (PCR) tests, are given in African countries. If this is the reason, future increases of the medicinal tests in Africa may cause result in undesirable increases of in the number of cases therein African counties.

We are hopeful that the COVID-19 pandemic will be eradicated in the next year, consequently no necessary for the rendering a Special Issue Part 4.

Background: Earlier studies have indicated the BA.5 sublineage of Omicron variant strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as more infective than BA.2. Object: This study estimated BA.5 infectivity while controlling other factors possibly affecting BA.5 infectivity including vaccine effectiveness, waning effectiveness, other mutated strains, Olympic Games, and countermeasures. Method: The effective reproduction number R(t) was regressed on shares of BA.5 and vaccine coverage, vaccine coverage with some delay, temperature, humidity, mobility, shares of other mutated strains, countermeasures including the Go to Travel Campaign, and the Olympic Games and associated countermeasures. The study period was February 2020–July 22, 2022, using data available on August 12, 2022. Results: A 120 day lag was assumed to assess waning. Mobility, some states of emergency, vaccine coverage and those with lag, and the Delta and Omicron BA.2 proportions were found to be significant. The omicron BA.1 proportion was significant, but with an unexpected sign. The estimated coefficient of BA.5 was negative but not significant. The Go to Travel Campaign was significantly negative, indicating reduced infectivity. The Olympic Games were negative but not significant, indicating that they did not raise infectivity. Discussion: The obtained estimated results show that BA.5 did not have higher infectivity than the original strain. It was lower than either Delta or Omicron BA.2 variant strains. That finding might be inconsistent with results obtained from earlier studies. This study controlled several factors potentially affecting R(t), though the earlier studies did not. Therefore, results from this study might be more reliable than those of earlier studies.

Strategic planning in response to disasters is distinctly different from strategic planning in normal situations. The experience of the coronavirus disease 2019 (COVID-19) pandemic has shown that a vaccine rollout program as a disaster response requires a different approach from current routine vaccination and disaster response frameworks. A holistic conceptual framework for planning vaccine rollout disaster response programs is proposed, building on the experience of COVID-19. The customizable framework was developed to have high dynamicity, flexibility, and applicability, incorporating key decision-making factors and suitable time frames (phases and transitions), based on roadmapping principles and techniques. In this research, we focus on the COVID-19 pandemic vaccine rollout program in the United Kingdom (UK) as a representative case of disaster response planning due to the availability of public data and access to the relevant stakeholders. We applied Platts’ process approach as a methodology and used various sources of information including an extensive literature review, expert interviews, and retrospective roadmapping (mapping past experience). As a result, we propose a strategic roadmapping framework for the COVID-19 vaccine rollout program to support visual planning of time-based strategies with the integration of various resources and demand environments. Apart from this practical contribution, we demonstrate that the concept of roadmapping can be applied beyond technology and innovation management domains to a novel research domain such as disaster response.

In 2022, the coronavirus disease 2019 (COVID-19) continues to spread worldwide with the emergence of many variants. Healthcare workers (HCWs) are encouraged to be vaccinated against COVID-19 because vaccines provide powerful protection from serious illnesses, hospitalization, and death. However, breakthrough infections on vaccinees have been frequently reported, and more studies are required to understand the mechanism of breakthrough infection and establish a standard neutralizing antibody (NTAb) level with efficacy. In particular, it is important to develop useful research tools for HCWs at high risk of breakthrough infection. Here, we administered a brief questionnaire on awareness of COVID-19 vaccines and antibody tests to uncover the needs of HCWs. Our questionnaire showed that HCWs felt a lower priority for vaccines among infection control measures than non-HCWs. On the other hand, HCWs expected more strongly the vaccine to be effective in preventing infection at work than non-HCWs. About half of the respondents, whether HCWs or not, thought that there was a correlation between the severity of adverse reactions and the degree of antibody induction. About 20% of the respondents had a change in awareness of the correlation after an antibody survey. Many respondents believed that the antibody test would be useful. Therefore, we should contribute to the development of a method of evaluating vaccines that can protect against infection and to improving other infection control measures in the future.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of novel coronavirus disease 2019 (COVID-19), a major cause of atypical pneumonia worldwide. Elderly individuals and those with underlying illnesses, such as cardiovascular and pulmonary diseases, are at a high risk of experiencing severe symptoms and have high mortality rates. There is therefore a major need to develop additional vaccines, effective treatments, and complementary drugs to control this infection. Lactoferrin (LF), a naturally-occurring glycoprotein, is bioactive against viruses and other pathogens. LF has a unique immunomodulatory function and is indispensable for immunity in infants. It is thought to contribute to biological defense in individuals across all generations, not only infants. LF inhibits viral adhesion to host cell surfaces through ionic binding to glycosaminoglycans and/or specific binding to viral structures. Purified LF is cost-effective and orally available as a dietary supplement. Here, we review studies on the protective role of LF against common viral infections. Based on this review, we propose that LF can be a possible prophylactic or therapeutic agent for COVID-19 disease.

The widespread application of social media in the field of crisis management has been adopted globally. In recent years, the role of social media in emergencies has grown, especially during the coronavirus disease 2019 (COVID-19) pandemic. This study explores the different roles played by social media in the government, the media, and the public during the pandemic through the key nodes of information dissemination at each developmental stage of crisis risk communication. The results indicate that in a government-led environment, in which social media is the link and the public is the core, attention must be directed towards the key role of social media as a “whistleblower” during the incubation period of a crisis event. Moreover, a new gatekeeping mechanism that integrates the public, the media, and the government should be formed to improve emergency management during crises.

Since 2020, the outbreak of the coronavirus disease 2019 (COVID-19) pandemic has affected the entire world, and networks of human connections were identified as a factor that had potentially impacted the geographical spread of COVID-19. With the help of social media platforms, these networks have connected populations across the word and allowed people to view each other in close virtual proximity. Consequently, the Social Connectedness Index (SCI) is used to measure the strength of social connectivity across geographical regions through friendship ties on Facebook. The importance of social networks—and their relation to human connections—may correlate with the spread of COVID-19. Since these networks can have a potential effect on the spread of COVID-19, it is crucial to identify the factors that were associated with its spread during the pandemic. In order to analyze SCI data, a social network analysis was conducted to define the network parameters and perform calculations using graph theory. A correlation analysis was also performed to identify factors that correlated with the spread of COVID-19 cases using the data in the United States (US). Finally, the machine learning model was used to create a case prediction paradigm from the network parameters. The results showed that SCI can be used as a parameter to create a pandemic prediction model. Multiple linear regression also yielded satisfactory results that predicted the total number of positive cases measured by adjusted R². In terms of the time frame, this study suggested that the parameters from the previous week can be used to predict the number of weekly infections. The findings showed that social networks had a greater impact on the prediction of current active cases than total positive cases. The social networks between counties within a state also held more importance than those across states.

This study surveyed adult web monitor enrollees about the lives of and stress experienced by Japanese children and adolescents during the prolonged coronavirus disease 2019 (COVID-19) pandemic. The survey was conducted on February 10, 2022 (after the sixth wave) and August 19, 2022 (during the seventh wave of the COVID-19 pandemic in Japan), with 231 and 217 survey participants, respectively. The questionnaire was designed so that adults could assess the frequency of exercise, and difficulties experienced by children and adolescents around them. Regarding exercise opportunities, 22% of parents of middle and high school children reported that children’s exercise opportunities “stayed the same” or “increased considerably” in the first survey. Whereas, in the second survey, all parents of middle and high school children reported that children’s exercise opportunities “decreased.” Regarding stress, 17% of parents of adolescents 18 years and older responded that the stress experienced was the “same as before” or “a little less than before” in the first survey, but all of these parents responded “quite a bit” to the same question in the second survey. The findings suggest that the life changes caused by the COVID-19 pandemic may have a significant impact on children and adolescents and may increase stress. The long-term effects of the COVID-19 pandemic on children and adolescents should be further investigated.

Little is known about information seeking and its influence on preventive behaviors among immigrants in Japan, despite their vulnerabilities during the coronavirus disease 2019 (COVID-19) pandemic. This study investigated information seeking about COVID-19, and examined differences with compliance with preventive measures between immigrants and the host population in Japan based on an Internet survey conducted in October 2021. We used chi-squared tests to determine the difference in information seeking and preventive behaviors between the two groups, and Poisson regression with robust standard errors to examine the association between information seeking and compliance with preventive measures. Our results show that, although the overall tendencies of information seeking and the preventive behaviors of immigrants were similar to those of the Japanese, significant differences were identified in some behavior: immigrants were more likely to acquire COVID-19 information from social networking services (SNS) and official websites in Japan, and maintain physical distance and ventilation than Japanese locals. Furthermore, immigrants’ sources of information diversified according to their sociodemographic characteristics (e.g., educational level, Japanese language skills, length of residence in Japan, and country or region of origin). Additionally, the effects of information seeking on preventive actions against COVID-19 differed according to the information sources; some information sources (e.g., SNS) had different impacts on preventive behaviors between immigrants and Japanese locals. Obtaining information from traditional media and Japanese official websites increases engagement with all five preventive measures among immigrants and four measures among the Japanese. The study highlights the importance of customized health policies for immigrants according to their behavioral tendencies.

Three years have passed since the first case of coronavirus disease 2019 (COVID-19) caused by the novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although the pandemic has slowed down gradually, the situation is not yet stable. Since COVID-19 has spread mainly in developed European and American countries, it is considered to be said a peculiar infectious disease. It has a significant impact on medical systems in developed countries in across the globe. In the past three years, the COVID-19 epidemic has changed gradually, both globally and regionally.