In our ongoing fight against the COVID-19 pandemic, how can we avoid following a “reconnaissance-by-fire” strategy? This statement discusses the need to find a new testing strategy.
Testing for SARS-CoV-2 is one of the fundamental tools in fighting the current pandemic. However, it should be borne in mind that the aims of testing shift depending on the stage of the pandemic. At the early stages, back in spring of this year, the spread of the COVID-19 pandemic in Poland was greatly slowed. This was undoubtedly the result of lockdown measures, imposing severe restrictions on social behavior and the economy. At the time, the rational goal of testing was to detect and control chains of infection and any sources of outbreaks. However, as the spread of the pandemic slowed in May and June, we became collectively less vigilant about the virus. There were even rumors that the threat posed by the pandemic had been exaggerated. As a result, the testing system – used at the early stages of the pandemic to identify infected individuals and trace those they had been in contact with – became essentially ineffective. In late August and early September, as people returned from holiday to their homes, offices, schools and universities, the daily number of recorded infections began to rise dramatically. This could have been prevented back in the summer through the introduction of strict rules aiming to prevent the spread of the virus, such as maintaining social distancing, washing or disinfecting hands and surfaces regularly and wearing masks. Additionally, while the numbers of infections of the upper respiratory tract remained low, the capacity of the testing system should have been expanded and updated to cope with the increased numbers of infections forecast for the autumn.
However, appeals by experts remained largely ignored. As a result, by early November over 20,000 new cases were being recorded every day, with the number of deaths also rising rapidly (at the highest rate in Europe). The capacity of the testing system quickly became overwhelmed, and imposing quarantine on patients became virtually impossible. As the number of reported daily infections was increasing by 50-fold, the number of people placed in isolation rose only fivefold, to stabilize at around 450,000. The situation is reaching critical levels, and a change to our healthcare policy, including testing strategy, is essential.
In the meantime, the testing system currently in use in Poland is mainly limited to testing individuals with clear upper respiratory system symptoms. This means that asymptomatic individuals or those whose symptoms are mild or atypical are not being identified. According to estimates, their numbers may be up to ten times higher than the official daily reports, and there are also indications that they are most likely to spread the virus. This means that on the population scale, this testing system does not provide accurate information on the stage of the pandemic in the country. Such information would be extremely valuable and it would help us develop a rational plan for dealing with the pandemic. Therefore, we recommend changing the testing strategy so that this key information becomes available at the next stages of the pandemic. Let us start by addressing three questions.
Testing has three main goals: 1) to provide information on the spread of the pandemic by monitoring a defined population, 2) to quickly identify individuals who may be responsible for spreading the infection, thus accelerating the spread of the pandemic, and 3) to quickly detect infection in individuals at high risk of developing severe symptoms, so as to provide them with optimal care and thus limit the number of excess deaths.
We need to change our strategy to focus on testing those individuals whose jobs involve interacting with many people and who therefore may contribute to a significant spread of infection. These include healthcare workers, teachers, uniformed services, municipal service workers and all individuals providing essential services. All such individuals should have easy access to rapid testing; this will make it easier for them to continue working and self-isolate quickly in the event of a positive result, so as to prevent them from spreading the infection. There are also individuals for whom infection with SARS-CoV-2 poses a particularly great health risk. If there is even the slightest chance that they might have been exposed, they should also have rapid access to individual testing.
Given the current epidemiological situation, all individuals who feel unwell or are experiencing any respiratory symptoms should strictly adopt the assumption that they are infected with COVID-19. We should introduce a universal policy that if anyone is feeling unwell, they should stay at home and avoid contact with others. Only once they have been free of any symptoms for three continuous days should they resume their previous activities. Implementing such standards would not pose negative consequences to the economy or public health, since many professions have already adopted remote working on a wide scale. If a patient’s symptoms worsen during isolation, or they are in a high risk group, they should consult a doctor who will advise whether they should seek further help. However, hospitals should only admit individuals who require urgent specialist attention. Additionally, adopting such a strategy would also significantly limit the spread of seasonal cold, flu and other airborne infectious diseases.
Testing with the aim of determining the true scale of the pandemic in Poland is a separate issue. It is impossible to test the entire Polish population, therefore we must focus on monitoring a selected subgroup. Many countries monitor the spread of respiratory viruses by testing all individuals showing symptoms in a given population. This system has been used successfully to track flu for many years (SENTINEL), although it is not as effective when it comes to COVID-19. This is due to the fact that the course of infection with COVID-19 depends on age; we could use the existing system to monitor the spread of disease among adults while completely missing how it is disseminated among children and young people. As such, it seems that the only viable option is systematic testing for SARS-CoV-2 in a representative sample (individuals selected at random from the national ID database and tested periodically). Given how widespread the pandemic currently is, the sample group should be as large as possible. Only such widespread testing will help us in our fight against the pandemic. It will help us answer questions such as whether reopening schools will result in a rapid growth in the number of infections, or whether reopening theatres, cinemas, museums, gyms and swimming pools will have a significant effect on the spread of the pandemic. Such a testing strategy will allow for a more nuanced course of action than “slamming on the breaks.” In short, we postulate that at this stage of the pandemic the main aims of testing should be monitoring the level of penetration of SARS-CoV-2 in high-risk groups and population testing on a randomly selected sample.
In order to detect the virus, we apply a test able to detect the presence of RNA specific to the SARS-CoV-2 virus (genetic testing) or a protein specific to the virus (antigen testing). Genetic testing has been the gold standard in diagnostics of viral infections for many years. When conducted correctly, it is a reliable diagnostic tool. However, it is relatively expensive and in most cases results take up to a few days to arrive.
The first-generation antigen tests currently seem to be worthless, but the second-generation tests are proving to be relatively reliable. While they offer lover sensitivity and specificity than genetic testing, they are sufficiently effective to detect infection with the SARS-CoV-2 virus in the early days of COVID-19 symptoms. After five to seven days from the onset of symptoms, the reliability of antigen tests rapidly diminishes. Antigen tests are significantly cheaper than genetic tests and results are available in around an hour. However, it should be noted that many such tests currently on the market do not meet even the most basic standards, and only tests recommended by the National Institute of Public Health – National Institute of Hygiene or a specialist virologist should be used.
In summary, there are two tools available for detecting the SARS-CoV-2 virus. One is antigen tests, which should be used systematically in individuals experiencing symptoms indicating COVID-19 who want to make sure they don’t pose an infection risk. In turn, genetic tests should be used exclusively in patients who may not be experiencing typical COVID-19 symptoms but who may have been exposed to the virus (up to a week previously), and whose jobs (healthcare, education or uniformed services) require highly accurate information on infection rates and rapid isolation in case of infection.
In each given country, the testing strategy should be adapted to the changing pandemic situation. The strategy outlined here will also need to be modified as the situation in Poland changes. If and when we return to low numbers of new daily cases, it may be advisable to return to a test-and-trace system. This should be decided by epidemiologists alongside economists.
This statement has been prepared by the Interdisciplinary COVID-19 Advisory Team to the President of the Polish Academy of Sciences. The team is led by Prof. Jerzy Duszyński, President of PAS, with Prof. Krzysztof Pyrć (Jagiellonian University) acting as deputy. Dr. Aneta Afelt (University of Warsaw) is the secretary of the board. Other members are Prof. Radosław Owczuk (Medical University of Gdańsk), Dr. Anna Ochab-Marcinek (PAS Institute of Physical Chemistry), Dr. Magdalena Rosińska (National Institute of Public Health – National Institute of Hygiene), Prof. Andrzej Rychard (PAS Institute of Philosophy and Sociology) and Dr. Tomasz Smiatacz (Medical University of Gdańsk).
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