Fueled by 90-mile-per-hour winds, the Eaton wildfire in Los Angeles County began on January 7, 2025, and firefighters did not contain it until January 31. The blaze killed 19 people and forced the evacuation of about 100,000 people, according to a study in yesterday’s Morbidity and Mortality Weekly Report. 

Many of the evacuees needed to stay in a shelter, including some of the about 1,800 people transported from assisted or skilled nursing facilities. By January 13, reports emerged of gastrointestinal illness, COVID-19, and flu in people staying at the Eaton wildfire evacuation shelter, and these concerns were filtered to the Pasadena Public Health Department (PPHD). To contain possible outbreaks, public health staff recommended bolstered monitoring and infection prevention and control (IPC) efforts and the addition of several isolation areas. 

“Infectious disease outbreaks in evacuation shelters are an important public health concern and exacerbate the challenges faced by persons seeking safety during and after an emergency,” wrote the authors of the paper, led by the PPHD. 

“Rapid implementation and sustained adherence to standardized IPC protocols should be part of standard shelter establishment procedures,” they added. “Early adaption of these measures can reduce transmission, morbidity, and mortality, and decrease the likelihood of outbreaks.” 

Immediately after the public health department received reports of illness, staff visited to identify ways the shelter could improve its ICP measures. 

Public health experts observed improper hand washing and incorrect usage of personal protective equipment. Many of the cleaning products did not disinfect against norovirus, and the shelter had no isolation space. 

Infectious disease outbreaks in evacuation shelters are an important public health concern and exacerbate the challenges faced by persons seeking safety during and after an emergency.

The shelter staff made the recommended changes, and both Pasadena and California public health staffers regularly visited the shelter to ensure proper implementation of the ICP measures. 

In addition to the recommended changes, the PPHD and the California Department of Public Health tracked ill shelter residents when they sought care from the medical staff, as well as staff members when they participated in testing or reported illness to their supervisors. 

Public health officials detected 104 cases of norovirus, 56 cases of COVID-19, 29 cases of flu, and 30 cases “nonspecific respiratory illness” among evacuees and staff members. Of all the ill shelter residents, 11 had co-infections—four people with norovirus and COVID-19, five with norovirus and flu, and two with COVID-19 and flu. 

It’s possible that the experts failed to capture some illnesses, because people with milder symptoms might not have sought medical treatment or employees did not report an illness to their supervisors, the authors noted. What’s more, declining cases of illness could be related to fewer people staying in the shelter. 

Still, the authors underscore the importance of infection control and prevention in communal shelters following climate emergencies. 

“Outbreak control measures can be challenging to implement after disasters when many persons with limited alternative housing options and varying medical needs are seeking immediate shelter,” the authors wrote. “This challenge can be exacerbated when multiple communicable diseases are circulating within a community, each requiring a tailored prevent approach.”