Investigation of SARS-CoV-2 Transmission Associated With a Large Indoor Convention - New York City, November-December 2021.

During November 19-21, 2021, an indoor convention (event) in New York City (NYC), was attended by approximately 53,000 persons from 52 U.S. jurisdictions and 30 foreign countries. In-person registration for the event began on November 18, 2021. The venue was equipped with high efficiency particulate air (HEPA) filtration, and attendees were required to wear a mask indoors and have documented receipt of at least 1 dose of a COVID-19 vaccine.* On December 2, 2021, the Minnesota Department of Health reported the first case of community-acquired COVID-19 in the United States caused by the SARS-CoV-2 B.1.1.529 (Omicron) variant in a person who had attended the event (1). CDC collaborated with state and local health departments to assess event-associated COVID-19 cases and potential exposures among U.S.-based attendees using data from COVID-19 surveillance systems and an anonymous online attendee survey. Among 34,541 attendees with available contact information, surveillance data identified test results for 4,560, including 119 (2.6%) persons from 16 jurisdictions with positive SARS-CoV-2 test results. Most (4,041 [95.2%]), survey respondents reported always wearing a mask while indoors at the event. Compared with test-negative respondents, test-positive respondents were more likely to report attending bars, karaoke, or nightclubs, and eating or drinking indoors near others for at least 15 minutes. Among 4,560 attendees who received testing, evidence of widespread transmission during the event was not identified. Genomic sequencing of 20 specimens identified the SARS-CoV-2 B.1.617.2 (Delta) variant (AY.25 and AY.103 sublineages) in 15 (75%) cases, and the Omicron variant (BA.1 sublineage) in five (25%) cases. These findings reinforce the importance of implementing multiple, simultaneous prevention measures, such as ensuring up-to-date vaccination, mask use, physical distancing, and improved ventilation in limiting SARS-CoV-2 transmission, during large, indoor events.†.

Follow-up assessment of health consequences after a chlorine release from a train derailment--Graniteville, SC, 2005.

INTRODUCTION: After a train derailment released chlorine gas in Graniteville, South Carolina, in 2005, a multiagency team performed an epidemiologic assessment of chlorine exposure and resulting health effects. Five months later, participants were resurveyed to determine their health status and needs and to assist in planning additional interventions in the community. METHODS: Questionnaires were mailed to 279 patients interviewed in the initial assessment; follow-up telephone calls were made to nonresponders. The questionnaire included questions regarding duration of symptoms experienced after exposure and a posttraumatic stress disorder (PTSD) assessment tool. RESULTS: Ninety-four questionnaires were returned. Seventy-six persons reported chronic symptoms related to the chlorine exposure, 47 were still under a doctor's care, and 49 were still taking medication for chlorine-related problems. Agreement was poor between the first and second questionnaires regarding symptoms experienced after exposure to the chlorine (κ=0.30). Forty-four respondents screened positive for PTSD. PTSD was associated with post-exposure hospitalization for three or more nights [relative risk (RR) = 1.7; 95% confidence interval (CI)=1.1-2.6] and chronic symptoms (RR=9.1; 95% CI=1.3-61.2), but not with a moderate-to-extreme level of chlorine exposure (RR=1.2; 95% CI=0.8-1.8). CONCLUSIONS: Some victims of this chlorine exposure event continued to experience physical symptoms and continued to require medical care 5 months later. Chronic mental health symptoms were prevalent, especially among persons experiencing the most severe or persistent physical health effects. Patients should be interviewed as soon as possible after an incident because recall of acute symptoms experienced can diminish within months.

Rapid assessment of exposure to chlorine released from a train derailment and resulting health impact.

OBJECTIVES: After a train derailment released approximately 60 tons of chlorine from a ruptured tanker car, a multiagency team performed a rapid assessment of the health impact to determine morbidity caused by the chlorine and evaluate the effect of this mass-casualty event on health-care facilities. METHODS: A case was defined as death or illness related to chlorine exposure. Investigators gathered information on exposure, treatment received, and outcome through patient questionnaires and medical record review. An exposure severity rating was assigned to each patient based on description of exposure, distance from derailment, and duration of exposure. A case involving death or hospitalization > or = 3 nights was classified as a severe medical outcome. Logistic regression was used to examine factors associated with severe medical outcomes. RESULTS: Nine people died, 72 were hospitalized in nine hospitals, and 525 were examined as outpatients. Fifty-one people (8%) had a severe medical outcome. Of 263 emergency department visits within 24 hours of the incident, 146 (56%) were in Augusta, Georgia; at least 95 patients arrived at facilities in privately owned vehicles. Patients with moderate-to-extreme exposure were more likely to experience a severe medical outcome (relative risk: 15.2; 95% confidence interval 4.8, 47.8) than those with a lower rating. CONCLUSIONS: The rapid investigation revealed significant morbidity and mortality associated with an accidental release of chlorine gas. Key findings that should be addressed during facility, community, state, and regional mass-casualty planning include self-transport of symptomatic people for medical care and impact on health-care facilities over a wide geographic area.

Health information privacy and syndromic surveillance systems.

The development of syndromic surveillance systems to detect potential terrorist-related outbreaks has the potential to be a useful public health surveillance activity. However, the perception of how the Health Insurance Portability and Accountability Act of 1996 (HIPAA) Privacy Rule applies to the disclosure of certain public health information might affect the ability of state and local health departments to implement syndromic surveillance systems within their jurisdictions. To assess this effect, a multiple-question survey asked respondents to share their experiences regarding patient confidentiality and HIPAA Privacy Rule requirements when implementing syndromic surveillance systems. This assessment summarizes the results of a national survey of state terrorism-preparedness coordinators and state epidemiologists and reflects the authors' and others' experiences with implementation.