Why we need to take manual contact tracing (more) seriously

In April, the Dutch government announced its intention to develop a corona-app that could be used in contact tracing. Other countries like China (Vervaeke, 2020), Australia, Singapore, the United Kingdom and Norway are already implementing or piloting such an app (Servick, 2020). However, concerns over the privacy of the app may be as widespread as the idea to set up such a system (see for example Daalder, 2020), and there are doubts about reliability as well (Kelion, 2020; Servick, 2020). One computer scientist ‘worries Bluetooth-based apps will fail to alert people of risky encounters and flood them with false alarms’ (Leith, D., in: Sevick, 2020). 

Meanwhile, places like Ireland, San Francisco, Massachusetts (Barry, 2020) and Germany (The Economist, 2020) are focusing on more traditional methods of contact-tracing instead, hiring thousands of people to conduct manual, human-to-human contact-tracing. In the Netherlands, the Gemeentelijke Gezondheidsdiensten (GGD) recently announced that they will be cooperating with the Red Cross and SOS International in an effort to improve their contact-tracing capacity (GGDGHOR, 2020).

The Case of Ebola

Manual, human-to-human contact-tracing is a time-tested method that has contributed to the worldwide elimination of smallpox and SARS (Fowler, 2020). It also contributed to the fight against tuberculosis, which is now largely eradicated in the Netherlands, but not in the world. Whenever a patient with tuberculosis is found, contact tracing is started to prevent local spread of the disease (Velduizen, 2020; RIVM, 2020). Contact tracing is also used against many other diseases such as HIV (Fowler, 2020), Polio (Courage, 2014), and even the Plague (WHO, 2017) and has been pivotal in Rabies control as well as in the 2014-2016 Ebola outbreak in west-Africa and the ongoing outbreaks of Ebola and measles in the Democratic Republic of Congo.

A case study from Lagos, Nigeria in 2014 demonstrates the enormous potential benefits of human-to-human contact tracing (Courage, 2014). Just after landing at the airport of Nigeria’s capital Lagos, a passenger collapsed and was taken to hospital. Three days later, he was diagnosed with Ebola. Immediately after, contact tracing was started. During the following months, 989 contacts were traced. The contact tracing team did not use a fancy app. Rather, they visited each of these contacts, armed with thermometers. During the 21-day incubation period of Ebola, each contact was visited three times a day to measure their temperature and check for symptoms, adding up to a staggering 18500 visits in total. When one of these contacts started developing any kind of symptoms, they were immediately isolated and tested for Ebola. During the following months, 19 people were diagnosed with Ebola, and one additional person died of what was probably Ebola before being tested. In the end, eight people died (Fasina et al., 2014). Nevertheless, a large outbreak of the disease was prevented.

Although laborious, the contact tracing was well worth the effort. The Ebola cases in Nigeria in 2014 were part of a much larger outbreak in West Africa between 2014-2016. During this outbreak, 11315 people died from Ebola in West Africa (O’ Carrol & Jones, 2016). With 50% of those infected dying from the disease on average (WHO, 2020a), the stakes were extremely high in Nigeria. Medication and vaccines for Ebola were not yet available at the time (Molteni, 2019; Branswell, 2020). Moreover, Lagos, with 21 million inhabitants, is Africa’s largest city (Courage, 2014). An outbreak in such a large city could have serious consequences for many people. Moreover, with its airport, Lagos is well connected to the rest of the world, just like Wuhan. Already, one patient inadvertently carried Ebola from Lagos to the Nigerian city of Port Harcourt by plane (Fasina et al., 2014). It is probably safe to say that, through their prompt action, the public health heroes of the Nigerian contact tracing team may have saved thousands of lives in as well as outside Nigeria.

One of the advantages of manual contact tracing is that by frequently phoning or visiting, health workers may gain the trust of their ‘contacts’ (Barry, 2020). In the case of Ebola, the efforts to fight the disease have often been hindered by distrust of health workers, and of authorities in general (Campbell, 2019). Teams of health workers in a war-area in Congo have even been under attack (Burke, 2019). For this reason, gaining the trust of patients and their communities really can be crucial in the case of Ebola (Courage, 2014), but is likely to be important  for other diseases as well. When contacts trust the health workers contacting them, they may be more honest about contacts they had, and may more willingly comply with any isolation or treatment which may prove necessary (Murphy, 2014).

Implementing contact tracing for Covid-19

Although the example from Nigeria demonstrates the enormous potential of manual contact tracing in fighting diseases, the situation for Covid-19 in the Netherlands may be a little different. The fact that the first patient in Nigeria in 2014 collapsed while still at the airport meant that Ebola could be identified and contact tracing could be started within days of his arrival in Lagos. The first patient was on his way to give a lecture in the Nigerian city of Calabar. Had he arrived there, things could have been very different. He might have met and infected many more people before he was isolated and the contact tracing started (Courage, 2014). The already large number of contacts to be traced would have been enormous.

In the case of Covid-19, timely awareness of the disease’s presence in a region may be rare. For example, a first patient in France was already seriously ill from the virus in December, a month before the first ‘official’ case in the country was confirmed (Keulemans, 2020a), and the virus had probably been circulating in Northern Italy for weeks before people became aware of its presence in the region (Van der Ploeg, 2020). In the Netherlands, some patients already had symptoms even before carnival as well (Keulemans, 2020b). This may affect the extensiveness and aims of contact tracing. In a document with guidance on contact tracing for Covid-19, the World Health Organization (WHO) (2020b) recommends that contact tracing is done exhaustively when cases are still sporadic, with the goal of suppressing transmission. This is the kind of approach Nigerian public health workers  implemented successfully in 2014. When a virus like Covid-19 has become more widespread, such extensive contact tracing may no longer be feasible, but contact tracing may still be of use to slow down transmission (WHO, 2020b). Even when local transmission is high, the WHO recommends that contact tracing should continue as much as possible, ‘focusing on household contacts, health care workers, high-risk closed settings (dormitories, institutions, long term-care homes), and vulnerable contacts, as well as maintaining strong contact tracing capacity in areas with smaller clusters of cases.’ In this light, the policy of the Northern provinces to continue testing and tracing, although criticized by the Dutch minister of Health (Bessems, 2020), was, in fact, in line with WHO guidelines. On the other hand, the refusal to test health workers working in residential care, even though testing capacity was sufficient (Heilbron & Kuijpers, 2020), was not in line with these WHO guidelines at all. 

The Dutch Contact tracing protocol differs from the WHO guidelines in other ways as well. For example, the WHO (2020b) recommends that contacts are phoned (or visited) each day for fourteen days after they had contact with a patient. During this time, body temperature and possible symptoms are closely monitored. In the Netherlands, patients are phoned just three times in total. According to a Dutch GGD director, contacts dislike daily phone calls. Contacts are asked instead to call the GGD themselves if they start developing symptoms (Van Heerde, 2020). But people may be reluctant to phone when reporting symptoms could have consequences (Nieuwsuur, 2020a). Some experts worry that the Dutch plans for contact tracing from June onwards are not thorough enough (Nieuwsuur, 2020c). Initially, GGDs were even planning to send contacts a letter asking to quarantine1 themselves and to contact the GGD if they developed symptoms, instead of phoning them. This plan was, fortunately, changed, because experts were critical (Nieuwsuur, 2020b). 

The WHO (2020b) writes that ‘when stringent public health and social measures are being adjusted, rapid identification of cases and contact tracing are critical to maintain low levels of transmission and rapidly identify and break new transmission chains.’ Now that the Netherlands are gradually reopening, contact tracing will become increasingly important to contain the virus. The examples of its use in the fight against Ebola and other infectious diseases demonstrate that, if conducted properly, contact tracing can help stop the spread of a disease and in this way potentially save many lives. It would be a bad thing if the Netherlands failed to use this potential by not being thorough enough in tracing contracts. Worryingly, after decades of austerity measures, the Dutch GGDs have to make do with minimal resources (Kuijpers, Van de Ven & Woutersen, 2020).

Although human-to-human contact tracing does not use GPS or Bluetooth, other technology may support the work of contact tracers. Contact tracing can be very complex, with contact tracers having to keep track of various databases with information about cases, their contacts, and follow-up and lab results for all of them (WHO, n.d.). Software can help create an overview of all the data. The WHO developed an app to do just this, called Go.Data. This is not an app used by the general public to keep track of their contacts through GPS or bluetooth, but software health workers may use to enter data during testing and tracing. Software like this can help health workers visualise the transmission chains of a disease and keep track of cases and their contacts (WHO, n.d.). Although applications like the Go.Data app can aid in contact tracing, such software does not replace the immensely valuable work contact tracers are doing worldwide. When fighting Covid-19, human-to-human contact tracing should not be neglected; it deserves all the support and attention it needs to be made into a success.

 1Quarantine means largely avoiding contacts, but is not as stringent as isolation, which is started when a contact becomes a ‘case’ – a person confirmed or (strongly) suspected to be infected by covid-19. During isolation, all contact with other people (who are not wearing personal protective equipment) is avoided (WHO, 2020b).

Many thanks to Amrish Baidjoe for his help and his explanation about contact tracing.


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