BACKGROUND: On May 19, 2017, the cluster of 6 acute respiratory infections due to adenovirus in the swimming department of a physical education school (School J) was reported to Korea Centers for Disease Control and Prevention. An epidemiological investigation was conducted to identify the transmission route of the infection and to control the outbreak. MATERIALS AND METHODS: A retrospective cohort study (Study 1) was conducted on students and teachers of the athletic departments using the swimming pool, and a prospective surveillance (Study 2) was conducted on all students and teachers of the School J. A case was defined as any student and school personnel who developed more than two of the following symptoms from April 10 to July 2, 2017: fever, sore throat, cough, rhinorrhea, or headache. Relative risks (RRs) were calculated to compare the attack rates according to potential risk factors. Multivariable logistic regression was performed to identify the risk factors for infection in the outbreak. RESULTS: 47 cases were identified: 33 (55.9%) cases occurred among 59 students and teachers in Study 1 and 14 (3.9%) among 362 students and school personnel in Study 2. There were 18 laboratory confirmed adenovirus infection cases. The common symptoms were headache (71.7%), fever (69.6%), rhinorrhea (63.0%), sputum (56.5%), and sore throat (54.3%). 23.9% of the cases were accompanied with diarrhea and 19.6% with eye congestion. None of the cases developed pneumonia. 32.6% of the cases were hospitalized. In Study 1, attack rate in the swimming department was higher than that in others (RR: 1.90; 95% confidence interval [CI]: 1.01-3.60). In Study 2, being a member of the shooting department (RR: 20.70; 95% CI: 4.90-87.47) and being a first year high school student (RR: 10.95; 95% CI: 2.90-41.33) were identified as risk factors for the infections. Genetic analyses of the adenoviruses showed 100% identical sequence in homology and confirmed the human adenovirus B55 (HAdV-B55). No adenovirus was detected at examining the water and environment of the swimming pool and dormitory. CONCLUSION The outbreak is inferred to be occurred via propagated transmission among the students in the same athletic department, while the students with symptoms of respiratory infection continued performing school activities without any restrictions. Infection control measures such as early detection of symptoms of respiratory infection and restriction of group activity are necessary to prevent respiratory infection outbreak in the communal living setting.

The hepatitis A virus (HAV) has been the leading cause of viral hepatitis in Korea since the 2000s. We aimed to describe the current status and regional differences in hepatitis A incidence. We studied the total number of hepatitis A cases reported to the Korea Centers for Disease Control and Prevention through the National Infectious Diseases Surveillance System between 2011 and 2013. Additionally, National Health Insurance Review and Assessment Service data and national population data from Statistics Korea were used. In total, 7,585 hepatitis A cases were reported; 5,521 (10.9 cases per 100,000 populations), 1,197 (2.3 cases per 100,000 populations), and 867 (1.7 cases per 100,000 populations) in 2011, 2012, and 2013, respectively. Fifty-eight patients were infected outside of the country and 7,527 patients represented autochthonous HAV infection cases. Autochthonous HAV infection occurred more frequently among men than women (4,619 cases, 6.1 cases per 100,000 population vs. 2,908 cases, 3.9 cases per 100,000 population). The incidence rate was higher in the 20-29 yr-old group (2,309 cases, 11.6 cases per 100,000 populations) and 30-39 yr-old group (3,306 cases, 13.6 cases per 100,000 populations). The majority of cases were reported from March to June (53.6%, 4,038/7,527). Geographic analyses revealed a consistently high relative risk (RR) of HAV infection in mid-western regions (2011, RR, 1.25, P=0.019; 2012, RR, 2.53, P<0.001; 2013, RR, 1.86, P<0.001). In summary, we report that hepatitis A incidence has been decreasing gradually from 2011 to 2013 and that some regions show the highest prevalence rates of HAV infection in Korea.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Databases, Factual ; Female ; Hepatitis A/*epidemiology/pathology ; Humans ; Incidence ; Male ; Middle Aged ; Republic of Korea/epidemiology ; Risk ; Seasons ; Sex Factors ; Young Adult

OBJECTIVES: In Korea, a national coronavirus disease 2019 (COVID-19) vaccination program was implemented, including 4 vaccines against COVID-19. A text messaging-based survey, in addition to a passive adverse event reporting system, was launched to quickly report unusual symptoms post-vaccination. This study compared the frequency of adverse events after COVID-19 vaccination based on the vaccine type and the type of 2-dose regimen (homologous or heterologous). METHODS: Self-reported adverse events were collected through a text-message survey for 7 days after each vaccination. This study included 50,950 vaccine recipients who responded to the survey at least once. Informed consent to receive surveys via text was obtained from the vaccine recipients on the date of first vaccination. RESULTS: The recipients of mRNA vaccines reported local and systemic reactions 1.6 times to 2.8 times more frequently after dose 2 than after dose 1 (p<0.001), whereas ChAdOx1-S recipients reported significantly fewer local and systemic reactions after dose 2 than after dose 1 (p<0.001). Local and systemic reactions were approximately 2 times and 4 times more frequent for heterologous vaccination than for BNT162b2/BNT162b2 and ChAdOx1-S/ChAdOx1-S regimens, respectively. Young individuals, female, and those receiving heterologous vaccine regimens including ChAdOx1-S/BNT162b2 vaccines reported more adverse events than older participants, male, and those with homologous vaccine regimens. CONCLUSIONS Although a heterologous regimen, youth, and female sex were associated with a higher risk of adverse reactions after COVID-19 vaccination, no critical issues were noted. Active consideration of heterologous schedules based on the evidence of efficacy and safety appears desirable.