Association between Cooperative Attitude and High-Risk Behaviors on the Spread of COVID-19 Infection among Medical Students in Japan

The impact of high-risk behaviors on the spread of COVID-19 infection among young people is an important problem to address. This study analyzed the association between cooperativeness and high-risk behaviors. We conducted a cross-sectional study among fourth-year medical students at Tokyo Medical and Dental University. The students were asked about cooperative attitude in a hypothetical situation of performing a task together with an unfamiliar classmate, who did not cooperate to complete the task previously. The response items were as follows: “cooperate”, “don’t want to cooperate and do it alone (non-cooperative)”, and “don’t want to cooperate and let the partner do it alone (punishment)”. Eating out and vaccine hesitancy were also treated as high-risk behaviors. Poisson regression was used to investigate the association between cooperative attitude and each high-risk behavior, adjusted for demographics. Of the 98 students, 23 (23.5%), 44 (44.9%), and 31 (31.6%) students chose “noncooperative”, “cooperative”, and “punishment”, respectively. Cooperative-type students exhibited 2.77-fold (PR: 2.77, 95% CI: 1.03–7.46), and punishment-type students exhibited 3.16-fold greater risk of eating or drinking out (PR: 3.16, 95% CI: 1.14–8.75) compared with those of the noncooperative type. Among medical students, the “cooperative” type and “punishment” type comprised the high-risk group for eating out during the pandemic

An Attenuated LC16m8 Smallpox Vaccine: Analysis of Full-Genome Sequence and Induction of Immune Protection

The potential threat of smallpox bioterrorism has made urgent the development of lower-virulence vaccinia virus vaccines. An attenuated LC16m8 (m8) vaccine was developed in 1975 from the Lister strain used in the World Health Organization smallpox eradication program but was not used against endemic smallpox. Today, no vaccines can be tested with variola virus for efficacy in humans, and the mechanisms of immune protection against the major intracellular mature virion (IMV) and minor extracellular enveloped virion (EEV) populations of poxviruses are poorly understood. Here, we determined the full-genome sequences of the m8, parental LC16mO (mO), and grandparental Lister (LO) strains and analyzed their evolutionary relationships. Sequence data and PCR analysis indicated that m8 was a progeny of LO and that m8 preserved almost all of the open reading frames of vaccinia virus except for the disrupted EEV envelope gene B5R. In accordance with this genomic background, m8 induced 100% protection against a highly pathogenic vaccinia WR virus in mice by a single vaccination, despite the lack of anti-B5R and anti-EEV antibodies. The immunogenicity and priming efficacy with the m8 vaccine consisting mainly of IMV were as high as those with the intact-EEV parental mO and grandparental LO vaccines. Thus, mice vaccinated with 10(7) PFU of m8 produced low levels of anti-B5R antibodies after WR challenge, probably because of quick clearance of B5R-expressing WR EEV by strong immunity induced by the vaccination. These results suggest that priming with m8 IMV provides efficient protection despite undetectable levels of immunity against EEV