Population Health Advisory Committee I. Summary of T3: Testing, Tracing and Tracking It is tempting to say we are too far behind to stop the epidemic. While we are behind in our response, we can slow it down. We know from previous outbreaks, including SARS and H1N1, as well as the 1918, 1957, and 1968 influenza pandemics that we can expect to see multiple waves. Our aim now is to minimize the second peak. The proven public health approach to COVID-19 includes three interventions to reduce exposure and new cases. The multiphase plan depends on widespread testing, extensive contact tracing and centralized isolation. Dr. Ashish Jha, director of the Harvard Global Health Institute explains that without testing, we are blindfolded and if we’re going to get testing ramped up, local and state officials and the private sector will have to do it. The "Wakayama model" in Japan adopted strict coronavirus testing policies and managed to curb the pandemic in their community. “It's a lesson in how nimble thinking and concerted action — grounded in fast, well-targeted testing and tracing — can beat back the novel virus and break its chain of transmission.” In South Korea, health officials tested a broader sample of the population, which allowed epidemiologists to better understand the extent of the disease in the community and target the response efforts. While there is community transmission, risk of exposure is not the same for every person in the area. The risk is greatest for persons who have/had prolonged close contact with a COVID-positive person. Considering the growing number of cases as COVID-19 circulated widely for weeks, and that we still do not have sufficient testing, it will be critical to invest in extensive contact tracing for every contact of every case to reduce transmission. Contact tracing is labor-intensive and the Center for Health Security estimates a need for 250-300 workers over the next four months for our current infection rates to be controlled in Bexar County. Zihong Lin (pages 7-8) did an analysis of the 25,000 cases in Wuhan and concluded that stay at home orders and social distancing practices reduced the spread but not enough to stop it until they offered centralized isolation. Family transmission is common so positive people are more likely to infect others in their household and close contacts in the community when there is a mandate for everyone to stay together at home. Furthermore, the CDC estimates that as many as 25% of cases may be asymptomatic and pre-symptomatic transmission occurred between one and three days before symptom onset. The SEIR diagram, a common epidemiological model, shows how individuals move through each compartment (Susceptible-Exposed-Infectious-Recovered/Removed). Even with tighter social distancing orders, the SEIR diagram shows that there will continue to be population movement between infected people and susceptible people without smart quarantine and centralized isolation (See Diagram 1 and 2). If we shelter in place without testing people with mild or no symptoms or without identifying likely positives through tracing, the emergency declaration will have limited impacts on suppressing this virus. Instead, we merely shift the peak. Germany’s model of testing, tracing and tracking/isolating in the early days allowed them to have a truer picture of their outbreak than places that only test symptomatic and most seriously ill or highest-risk patients. Population Health Advisory Committee Diagram 1. SEIR Model for COVID-19 without a comprehensive plan Diagram 2. SEIR Model for COVID-19 with a T3 plan Population Health Advisory Committee II. Testing There are two types of tests cleared for emergency use by the FDA: • Molecular tests are diagnostic for acute infection. These identify the presence of specific nucleic acids produced by the virus within swabs and respiratory samples. • Serology tests look for antibodies against the coronavirus. These identify if the person has immunity. Molecular tests SARS-Cov2 only contains RNA, which means it relies on infiltrating healthy cells to multiply and survive. A sample is collected from the nose or throat and is treated with several chemical solutions (reagents) to remove proteins and fats. In order to detect the virus, technicians need to convert the RNA to DNA so they can copy the sample (reverse transcription) hundreds of thousands of times (amplification). This produces a large enough quantity of the viral DNA to confirm the presence of SARS-Cov2. The sample mixture is then placed in an RT-PCR machine that cycles through temperatures that heat and cool the mixture to trigger specific chemical reactions. A standard real time RT-PCR setup usually goes through 35 cycles, which means it creates around 35 billion copies of the viral DNA in the sample. With good sampling technique, RT-PCR, in general, is highly sensitive and specific and can deliver a reliable diagnosis. It continues to be the most accurate method available for detection of the coronavirus. The difference between the automated RT-PCR and a manual RT-PCR is comparable to a boxed cake mix and a cake made from scratch. The automated kits (premixed reagents mixed with the sample) have significant benefits by reducing the risk of cross-contamination and minimizing errors caused by manual interventions. The manual RT-PCR can lead to more sample-to-sample variation, less reproducibility, and less precision when mixing reagents (like a cake from scratch where you measure all the ingredients). Many of the approved tests require nasopharyngeal (NP) swabs, which is a sample of secretions from the back of the nose and throat. The NP swab is difficult to do correctly and can be uncomfortable for the patient thus resulting in false negatives due to poor sampling technique. Given the supply issues with swabs and reagents, tests that use nasal rinses or even basic nose/throat swabs (better sampling ability) are ideal. Serology tests The FDA granted approval for four antibody tests. A test is performed on a blood sample from the patient to detect IgM (detectable several days after infection) and IgG (detectable later after infection) that are generated as part of the human immune response to the virus. In some cases, it can take up to 11 days for an individual’s immune system to produce the antibodies. That’s why the tests are not used to diagnose patients with COVID-19 that are showing symptoms within the first two or three days. Part of the reason these antibody tests would be valuable is it can provide guidance on people potentially returning to work or continuing quarantine. IgG antibody positivity suggests the person is recovered and most likely cannot be re-infected, which would be valuable to know for healthcare workers. If the tests are ordered, healthcare and other essential workers could be prioritized. The recovered workers could be assigned COVID-19 patients. They would still use protection, but it could help stabilize the workforce by reducing exposure to the workers who haven’t been infected. *Additional testing terms provided on page 9 and testing process and choices explained on page 10. Population Health Advisory Committee III. Tracing A case-based intervention like contact tracing is routinely used for tuberculosis, STDs, and foodborne disease but the typical timeline to prevent spread is on the order of weeks and capacity is limited to isolated outbreaks. Because COVID can be transmitted before people have symptoms, these contacts need to be identified and quarantined immediately after the case is confirmed. Even one missed case can undermine control efforts. Contact tracing requires: • Identifying an individual who has been clinically confirmed as having COVID-19; • Identifying and listing epidemiologically meaningful contacts of that individual; • Communicating with that list of contacts to warn them of potential exposure, and linking them to public health officials, diagnostic services, or self-isolation information and services; • Monitoring symptoms of people on the contact list until diagnostic results show that a person is not infected or are beyond a reasonable time frame, such as the incubation period of the virus; and • Visualization and analytics to optimize, monitor, and determine efficacy of contact tracers. Technological solutions will be helpful across many of these use cases With the growing number of cases and that we still do not have sufficient testing, it will be labor-intensive to control our current infection rates through identification and quarantine of exposed individuals. Based off of international experiences and current capacity, the Center for Health Security estimates Bexar County would need approximately 250-300 workers over the next four months. With secure, web-based IT support, most contact tracers should be able to work remotely via phone or other technologies to follow up on contacts and conduct interviews. The skills needed can be taught, no public health experience is necessary, and a high school education suffices. Case investigators and contact tracers receive training on the basics of disease transmission, how case isolation works and quarantine of contacts. The Association of State and Territorial Health Officials (ASTHO) created basic training modules for widespread use but the data collection protocol would need to be developed locally. San Antonio Metropolitan Health District Tracing Timeline Population Health Advisory Committee IV. Tracking (isolation) Smart quarantine and isolation is most successful when it is offered at the time of the positive result and when it is presented to community members as voluntary, convenient, and free. Adopting a smart quarantine plan requires public planning and funding for designated temporary accommodations and staff to monitor symptoms. Most people will recover and return home in about two weeks using a time-since-recovery strategy (>6 days since onset of symptoms and 72 hours of symptom resolution) or after testing negative at least twice.