The COVID-19 virus has vulnerabilities. The incubation period (the time from exposure to symptom onset) for most people with infection is four to six days but can be up to 14 days. This is long enough to take action to prevent further spread. And while many people with the infection show no symptoms, a significant proportion are symptomatic with fever and new onset of cough, so many cases can be identified. While no public health actions can prevent spread from all cases, these vulnerabilities suggest that containment actions can be partially successful in reducing community spread. Containment involves a combination of rapid case identification, case isolation, contact tracing, and contact quarantine.
Case identification through widespread laboratory testing
COVID-19 cases can be identified through laboratory testing of individuals with COVID-19 symptoms, and/or those with reasonable suspicion of exposure. The Philadelphia Department of Public Health, working with a large group of partner organizations, is expanding testing availability and access, as well as increasing testing volume.
The number of fixed test sites has increased to 56. The Department solicited proposals for additional testing services to reach vulnerable or hard-to-reach populations, received eleven proposals as of June 15, 2020, and funded the first proposal (from the Black Doctors COVID-19 Consortium) to conduct mobile testing. The number of tests conducted per day increased to 1,880 the week of May 24.
Protests and social unrest caused the temporary closure of some testing sites on May 30, with a reduction to 1,500 tests per day; most sites reopened in early June and the number of tests increased to an average 1,790 per day during the week of June 7.
Case isolation and quarantine
People with the infection are asked and provided with instructions to self-isolate for at least 10 days after the onset of symptoms to prevent the spread of the virus to others. (Note that this time period differs from the 14 days of quarantine for those exposed.)
The City of Philadelphia has provided hotel rooms for isolation for people with known or suspected COVID-19 infection, and for medically vulnerable individuals from homeless shelters, residential treatment facilities, or unsuitable environments, including the street.
As contact tracing expands, more people in need of isolation and quarantine at specialized facilities will likely be identified. In addition, people are likely to be identified who can isolate or quarantine at home, but only with external support. The Department of Public Health is drafting a solicitation for service providers to provide this in-home support.
The Department of Public Health is hiring staff to conduct contact tracing at the same time it is pilot-testing its procedures with existing staff. By July 1, the Department expects to have 70 staff hired, trained, and working to interview people with the infection, identify contacts, and counsel those contacts on quarantine.
Contact tracing staff will counsel contacts about their risk and need for quarantine and will connect them to testing and other supports as appropriate.
Contact tracing involves disclosure of information that is ordinarily kept private. Because of the importance of privacy, as well as the need to work with health departments from neighboring jurisdictions, contact tracing will be coordinated centrally by the Department of Public Health. For contact tracing to succeed, staff carrying out the work must be sensitive to the needs of those they are interviewing, and people with the infection must be comfortable with the staff; for this reason, the Department of Public Health will hire staff that are representative of the subgroups and communities from which the cases they are interviewing arise.