Commentary by Dr. Lilian Gandour | The Executive
This pandemic has been described as the defining global health crisis of our time. The novel coronavirus or SARS-CoV-2 is the cause of a deadly respiratory disease called COVID-19, currently affecting all continents, except Antarctica. Worldwide, the virus has infected more than 5 million individuals and resulted in more than 300,000 deaths. From early in the pandemic, scientists raced to develop a vaccine, and many countries rushed to implement public health non-pharmaceutical interventions (such as local and national lockdowns, closure of academic institutions, and wide-scale social and physical distancing) to slow the spread of the virus. Since mid-March, the Director General of the World Health Organization (WHO) Dr Tedros Adhanom Ghebreyesus has been stressing the importance of testing, testing, and more testing. Since lockdowns cannot go on forever (for social, economic, and mental health reasons), scaling up testing, isolation, and contact tracing to sustain the flattened curve in Lebanon (slowed transmission of the virus to ensure hospitals are not overrun) must be an integral component of a larger holistic national exit strategy.
Still, testing is not one size fits all. There are different types of tests, as well as different ways of testing. Testing policies, which vary across countries and over time within countries, also define the function and outcome of the testing procedure. In the initial phases of the epidemic in Lebanon, for example, the focus was on testing symptomatic individuals and key groups (elderly, individuals with severe symptoms or returning from an infected country, or those who have possibly encountered a confirmed case). The goal of that “targeted testing” has been the identification and isolation of cases and their contacts to suppress transmission. Early in April, the Lebanese government expanded its testing capacity, and fifteen additional testing sites were added to Rafik Hariri University Hospital (RHUH), the primary and only governmental center offering free testing services since the beginning of the epidemic. On April 5, Lebanon began the first phase of repatriation of Lebanese nationals stranded abroad, and naturally, the number of tests began to increase (with daily fluctuations in test numbers). Official reports are published daily documenting separately the results for residents versus returning expatriates to monitor the number of “imported cases” vis-à-vis “local cases,” the latter being more of an indicator of local transmission (though the burden on the local health care capacity is bound to be affected by the number of all infected cases, regardless of source). On April 20, the Ministry of Public Health began population screening or what they called “random testing” (though it is not so random, see below) in different areas of Lebanon. The open public testing was a step toward identifying asymptomatic cases (those who are shedding the virus without showing symptoms). With the gradual easing of lockdown measures since April 27 and the continued repatriation of expatriates, it should not be surprising if the numbers of new confirmed cases begins to rise again (especially if suspected cases are not quarantined, and people are not practicing social distancing). With the lifting of restrictions, the role of mass testing becomes even more critical for the containment and suppression of the virus spread. With that in mind, what do we need to know about testing?
Current mass testing is not so massive
Today, Lebanon has carried out approximately 60,000 polymerase chain reaction (PCR) tests in an estimated population of 6 million, so about 10,000 tests per 1 million. While the country’s testing capacity has been significantly improving and the ratio of total number of tests conducted thus far per million inhabitants is close to the world average (10,500 per million), it is still far from the ratios calculated for other countries such as the neighboring United Arab Emirates, which has a 15-fold greater ratio (150,000 tests per a million, among the highest globally). The number of daily tests conducted in Lebanon is variable, generally lower on weekends, and averaging in the past 10 days around 1,400 tests per day (though there is no official target, local experts have suggested the need for 2,500 to 3,000 tests per day in Lebanon).
Current random testing is not so random
Population screening can be done on a “self-selected” or a “random” group of people. When a group of individuals chooses to be tested, regardless of their symptoms or contacts, they will constitute a self-selected sample or a biased sample of the population from which they come (they came forward for personal reasons). The majority of that same population will remain untested, and within that group, some self-suspecting cases may not come forward for various purposes including access (most centers are in urban areas), cost (test free in RHUH only, and costs LL150,000-200,000 in other centers), stigma (fear of being labeled), or simply a lack of perceived need (asymptomatic case). This is what random testing aims to resolve. The standard dictionary definition of selecting subjects at random would be “without definite aim, direction, rule, or method.” This is far from the epidemiological definition of random sampling, which is very much methodical. In random sampling, a pool of people are identified (could be residents of a particular area), and each resident has a known, non-zero probability of being selected. When a random sample is tested for COVID-19, the percentage positive can then be extrapolated to represent the percentage of people affected in that community (with a certain standard error). This is not the case with the percentage derived from self-selected samples that represent only the tip of the iceberg. When testing capacity is limited, targeted testing is more justified to identify cases, trace contacts, and suppress spread. Without random testing, however, epidemiologists and public health officials in Lebanon can only hypothesize or predict (via mathematical modeling) but never truly know the true virus infection rate (nor the true case fatality rate) in the country. Random testing may be conducted nationwide, but amidst limited resources, they can begin to take place in selected areas or clusters, or targeted groups that may be considered most vulnerable such as the elderly or people with chronic conditions, or those groups whose conditions are less known to authorities, such as people living in rural areas or refugee camps.
Different tests tell a different story
The American Center for Disease Control (CDC) currently lists two types of tests for COVID-19: a diagnostic viral test and an antibody test. The most common diagnostic test is the molecular (RT-PCR) test (typically based on a nose or throat swab) that identifies active infections (people who are infected at the time of the test). Identifying and isolating active COVID-19 cases and tracing their contacts is necessary for providing treatment for those infected, and reducing the transmission of the virus from those infected to others. Still, the RT-PCR can neither tell us if the person was infected in the past (and recovered) nor guarantees immunity in the future. The RT-PCR test is typically highly accurate but concerns of false negatives have been reported for various reasons (for example, swab was not taken or stored adequately). Serological tests (or an antibody test on drawn blood) identify persons who were infected in the past and recovered (and ideally developed an immune response). Serological tests can provide insight on the evolution of the epidemic and whether the threshold for herd immunity has been reached. Serological testing in Lebanon is not yet recognized. The U.S. Food and Drug Administration (FDA) describes other newer diagnostic tests with their sets of benefits and limitations (e.g., rapid, point-of-care diagnostic antigen tests; at-home collection tests). Besides differences in their utility, existing tests also vary in their availability, cost, how the sample is taken, and the time needed to get the results back, and these aspects continue to evolve as test developers work to streamline the testing process.
It only counts if you count it
Bottom line, if you do not count it, it will not count. Epidemiological surveillance of COVID-19 allows us to understand the local dynamics of the virus, evaluate the containment of the spread, and make predictions. Surveillance data also informs local policies and interventions and allows stakeholders to re-evaluate their decisions continuously. As of May 22, Lebanon has recorded 1086 confirmed COVID-19 cases and 26 deaths, and the epidemic curve had been flattened until the recent surge in cases starting early May. Of course, conclusions are as valid as the numbers—and ours have largely been based on findings of known cases via targeted testing. Assuming a much higher number of undetected mild or asymptomatic cases in the community (which is likely the case for Lebanon), massive testing and epidemiological surveillance are integral to monitoring the actual spread of the virus in the community and to preventing transmission from asymptomatic persons to vulnerable individuals.
Testing may be the backbone but is useless alone
Testing is part of a holistic strategy to identify cases, trace their contacts, and isolate for precaution. Testing alone is futile and contact tracing without an effective plan to quarantine positive cases/isolate suspected cases is similarly useless. At the time of writing, 53 percent of the cases in Lebanon are due to contact with a confirmed case; moreover, 3 percent have an unidentified exposure. Mass testing strategies for COVID-19 have been described as central to lifting confinement restrictions, necessitating that significant logistics and capacity constraints are contextually addressed.
As we learn how to co-exist with COVID-19 in this new normal, we must have in parallel a plan to avoid new peaks and keep infection rates suppressed to avoid overburdening our healthcare system. This is until a vaccine or effective treatment is found. Mass testing (at least targeted, at best both targeted and random) needs to continue, and significantly improve in number and distribution to build a better and transparent information system about the presence, distribution and transmission of COVID-19 in the country and its various communities. On May 22, Lebanon recorded 62 cases (59 locals and 3 expatriates), the highest number recorded in locals since the start of the epidemic (with a 3 percent infection rate considering 2,100 tests were conducted). With the current easing of lockdown measures, resuming of economic activities, repatriation of expatriates, and potential re-opening of land borders and Beirut International Airport, Lebanon is in need of national strategy and perhaps additional local measures that consider the country’s particularities (limited resources and the prevailing economic crisis). This strategy must be evidence-informed, contextualized, and reflect a concerted, coordinated effort between government officials from various ministries, local epidemiologists working on COVID-19, and other stakeholders. Otherwise, we risk going back to square one.
- This article is originally published in The Executive on May 22, 2020
- Click HERE to read the Arabic version of theis article