Active monitoring of travelers who are at low (but not zero) risk for Ebola Virus Disease (EVD) for 21 days was a labor-intensive activity for health departments, especially those with large volumes of returning travelers. Taking on this new and daunting task was especially demanding while also sustaining ongoing public health responsibilities. New York City Department of Health and Mental Hygiene (NYC DOHMH) began receiving files from CDC with contact information for travelers who had arrived from West Africa in the fall 2014. An active monitoring call center (AMCC) was set up and staff from several different programs were reassigned from their regular jobs to serve as AMCC operators. After several months, these staff were replaced with grant hires and temp agency staff. They called travelers daily to collect temperatures and document any symptoms; these efforts are described in more detail at http://www.cdc.gov/mmwr/volumes/65/wr/mm6503a3.htm.
When a traveler was unable to be reached by AMCC for two consecutive days, the traveler was referred to the DOHMH Surveillance and Epidemiology Emergency Response Group’s Field Surveillance Unit (FSU). Activated under DOHMH’s Incident Command System, FSU consists of approximately 200 staff from six different bureaus. FSU staff are trained and experienced in patient/provider outreach, interviewing, and medical chart abstraction. Upon being assigned a traveler who was lost to follow-up, FSU staff initially attempted to contact the traveler or his or her listed emergency contact by phone. FSU staff used subscription-based people search databases to search for travelers or their emergency contacts to identify additional contact information. After calling all phone numbers and leaving messages for the traveler to call the AMCC, FSU staff would send an email to the traveler if an email address was available. If there was no response by phone or email after 2–3 hours, a FSU staff or team of two staff would conduct a site visit to the traveler’s home, hotel, or local address. If the traveler was not found, a letter from DOHMH explaining the need to speak with the traveler was left at the hotel’s front desk or under the apartment door, if possible.
From October 11, 2014 to May 31, 2015, DOHMH conducted active monitoring for 2,941 travelers, which resulted in 235 (8%) hard-to-locate referrals to FSU. Of the 235 referrals, 80 (34%) were successfully contacted by phone within a day of referral and 67 (29%) required a field visit. Of these 67 field visits, 17 (25%) were located and interviewed, letters asking the traveler to call were left with someone at the home/hotel or placed it under the door for 41 (61%), and 9 (13%) did not have a valid address. Seventy-eight (33%) of all referrals had other outcomes (e.g. traveler left NYC or contact made after 24 hours) and for 10 (4%) FSU was unable to proceed with any outreach due to lack of valid contact information.
Challenges in NYC to locating these travelers differed depending on if the traveler was a NYC resident returning from a trip abroad versus a foreign resident visiting the city. Challenges included the traveler not being reachable in the daytime because they were at work or not at the hotel because they were out sightseeing or visiting relatives. Incorrect or incomplete addresses lacking apartment numbers, no access to apartment buildings, common last names, language barriers, and safety in the field also hindered our ability to locate travelers.
Distributing pre-paid cell phones to travelers when they arrived facilitated efforts to contact them for daily active monitoring. In the first four weeks of active monitoring before CDC phones were given to travelers upon arrival in NYC, FSU had to identify additional contact information on travelers for 41 of 136 (30%) of referrals; after phones were distributed, only 14 of 99 (14%) required identifying additional contact information (2 P=0.004). Before phones were distributed, 49 of 136 (36%) referrals required a field visit; after phones were distributed, only 18 of 99 (18%) referrals required a field visit (2 P=0.003).
The number of referrals for locating hard-to-reach travelers decreased from 136 in November 2014 to 30 in December 2014 and remained less than 17 a month for the remaining months. This decrease was due to several reasons including AMCC’s success in contacting travelers by phone within 48 hours and the addition of free cellphones to travelers. However, valuable time and resources were still expended on calling travelers daily for 21 days and sending field staff to locate and make contact with travelers who did not respond to the cellphone attempts. Having a unit of staff trained and experienced in tracking down additional contact information, finding hard-to-reach people in the field, and interviewing reluctant clients was critical to the success of Ebola virus active monitoring in New York City.