To beat Covid-19, test everyone regularly

A mass, systematic population-wide testing for asymptomatic infections is the only way to eradicate the disease and avoid the ill effect of indiscriminate lockdown measures

By Professor Jose Vazquez-Boland, Chair of Infectious Diseases.

Published 9 July 2020

While inevitable at the beginning of the pandemic, due to the general lack of preparedness of governments and health systems, indiscriminate social restriction measures are unsustainable in a scenario of recurrent outbreaks —already taking place in different countries— and potentially new pandemic waves.

In addition to the impact on the socio-emotional interactions, wellbeing and civil freedoms, prolonging the application of lockdown measures (or reinstating them in response to local Covid-19 flair ups) can deliver a knockout punch to an already stumbling economy, with unpredictable consequences.

Clearly, a less socially disruptive and economically damaging approach is required. This needs to involve a testing strategy enabling the rapid targeting of interventions specifically on potential SARS-CoV-2 transmitters without affecting the general population.

The good news is that we actually have at our disposal all the necessary technical means and infection control know-how to achieve it. All that is needed is clarity, vision and determination in mobilising actions and resources in the right direction and at the necessary scale. Unfortunately, we are still far from getting there. ¹  

Testing only suspected cases will not defeat the virus

Restrictive testing policies directed at the confirmation of cases among those showing Covid-19 symptoms are short-sighted and a strategic error (even if involving contact tracing). With this approach the testing focuses on the tip of the iceberg whereas the bulk of Covid-19 transmission rests on the much larger hidden base of subclinical infections. ²

The measures that need to be implemented should address the problem at its core, that is the crucial role that asymptomatically-infected carriers have in the ‘silent’ spread of Covid-19, fuelled by the high transmissibility of the virus.

 Controlling Covid-19 without the generalised disruption caused by large-scale social restriction measures revolves around a two-pronged strategy:

(i) Mass, systematic, regular PCR-based screening of subclinical carriers

This should be implemented taking a public health (rather than health care) approach and cover the entire population of the country. The goal is to accurately pinpoint the foci of infection and monitor the spread of the virus in real time in order to quickly isolate Covid-19 carriers until they clear the virus.

The sampling should be organised locally around ‘interaction hubs or units’ and carried out by community health teams with specific knowledge of the local population, in direct liaison with field epidemiologists / public health officers under the coordination of regional and national health authorities. These interaction hubs / test units could be workplace-based (for example a company, business or education establishment), neighbourhoods, health-care centres, nursing homes, places of worship, shopkeepers/tenders of a section of a commercial street, etc.

Pooled sampling

Since the laboratory capacity is a critical limiting factor (testing should be based on sensitive, direct detection of actual virus carriage by PCR(polymerase chain reaction), not rapid antibody detection, indicative of past virus exposure), the tests can be easily implemented on pooled samples. This involves assembling in a single test the nasopharyngeal swabs of a number of individuals belonging to the same ‘interaction unit’, thereby substantially reducing the volume of laboratory tests to be initially performed. The exquisite sensitivity of the PCR test enables implementing this approach. Only if an ‘interaction unit’ gives a positive result, then individual tests are performed and investigation of contacts of positive individuals performed.

(ii) Full exploitation of the laboratory infrastructure of the country to scale up the testing capacity

The other cornerstone of the mass testing strategy is the effective utilisation of all the abundant complement of academic, research and technical laboratories across the UK, both public and private, to perform Covid-19 testing. Many of the personnel in these laboratories may have been, or still are, at home, due to the anti-Covid-19 measures and could be easily trained and deployed to perform these tests.

Universities, colleges and research establishments may play a crucial role by mobilising their expertise and laboratory facilities —many of which have remained or still remain dormant— to implement and even self-manage local testing programmes for both their students and staff and their surrounding communities.

Such an approach would be particularly vital for the higher education sector to safely resume on-campus activity with undergraduate and research students.

The goal is to create an extended ‘proximity’ laboratory network capable of absorbing a systematic, nation-wide Covid-19 testing plan in coordination with local NHS laboratories and supported by centralised reference laboratories and information processing centres. The reasons for this not having already been implemented are difficult to understand. Perhaps bureaucratic barriers and concerns regarding quality control and standardisation, coordination and information flow are playing a significant role here. 

However, we are facing an emergency comparable to war and we must understand that only an ambitious ‘brute-force’ screening strategy can effectively curb the Covid-19 pandemic. There is simply no other way around it in the absence of a vaccine.

A systematic, population-wide, carrier screening strategy will certainly require the mobilisation of substantial funding resources and a mighty logistics effort. But getting the economy back on track and people resuming normal life will always be better than spending colossal sums in just mitigating the disastrous consequences of the social paralysis caused by indiscriminate lockdown measures.

About the author

Professor Vazquez-Boland is the Chair of Infectious Diseases at the University of Edinburgh. He specialises in microbial virulence and bacterial infections. 

References 

_{1. Godlee A. Covid-19: Where's the strategy for testing. BMJ 2020;369:m2518. doi: https://doi.org/10.1136/bmj.m25182.}

_{2. Li R, et al. Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV-2). Science 2020;368:489–493. doi: 10.1126/science.abb3221#}

_{* This is a modified version of a note entitled "The strategy for testing: mass carrier screening for COVID-19 eradication" posted in the British Medical Journal in response to the article in reference [1].}

_{All images via Getty Images}