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 testing for the COVID-19 virus, contact tracing, isolation of persons with COVID-19, and quarantine of those exposed to others with the infection.
PCR testing for COVID-19 is available at more than 60 sites in every area of Philadelphia. Testing sites include pharmacies, federally qualified health centers, urgent care centers, and newly-established community sites operated by health systems. The number of persons tested per day has increased from several hundred in April to more than 5,000 in November. Rapid tests that detect COVID-19 virus antigens are increasingly available at testing sites.
Contact tracing began in June 2020 and teams were reaching more than 600 persons with COVID-19 per week in September. However, with the resurgence of COVID-19 in October and November leading to 1,000 or more cases diagnosed every day, contact tracing staff can no longer attempt to interview every case and assist with notification of contacts. As of November, 2020, the contact tracing unit is shifting responsibility for notifying contacts to those with the infection as much as possible. As part of this shift, the unit has written guidance on how a person with COVID-19 can identify and notify his/her own contacts of the need for quarantine.
Case isolation and quarantine
Persons with COVID-19 should remain in isolation – away from others – for 10 days after the onset of symptoms or the first positive test. Persons with close exposure to those with COVID-19 (within 6 feet for at least 15 minutes over a 24-hour period) should remain in quarantine – away from others – for 14 days after the last exposure. The Department of Public Health is providing assistance to a limited number of people who cannot safely quarantine on their own.