Testing and tracing: variations across countries

Hello, my name is Barbara McPake. I’m a health economist, and the health systems expert and I’m the director of the Nossal Institute for Global Health. And today I’m going to be talking to you about testing and tracing, the variations across countries, and what we can learn from that.

Policy and operational strategies on testing differ from country to country, region to region, and even city to city. These can depend on the progression of the disease, the level of preparedness in the specific context, and are also affected by resources and supplies availability, variants in governance, and political leadership, and different overall containment strategies.

This step builds on the discussion of testing in week one, which considered specific examples of testing, policies and approaches in different countries. As you work through the step think back to week one, and consider how these different testing approaches would be reflected in the test statistics that we discussed.

This slide highlights the range of aspects related to the health system, which may need to be explored when deciding on the testing approach to take. Decisions need to be around how a case and a suspect case is defined, what the capacity within the health system is to conduct quality testing, and to provide quality care to positive cases, and how usually scarce resources should be prioritized. There can be tests for the virus itself, but also blood tests showing immunity or antibodies, Invisible infections is the term used for the many people who are suspected of having COVID-19, but haven’t been able to receive a proper test. We’ve seen countries pursue very different strategies when it comes to testing for COVID-19.

WHO supports the policy of widespread testing, but policies across the world vary and there are extensive debates around the effectiveness of different approaches as relating to different phases of the pandemic as well as more broadly In many cases, it’s too early to tell how effective these different approaches are. Testing is vital though because asking people with mild symptoms just to stay at home, will lead to more infections in the household and community. If tested and positive, people can either be isolated in a facility, or put on strict home isolation, which they’re more likely to adhere to if they know that for sure they have the virus.

However, when resources are limited and the health system is overloaded, the preference may be to avoid a lot of non-sick people coming to health facilities for testing. And therefore, risking contagion. So, as this slide shows, often some difficult questions need to be asked to inform specific context-appropriate testing approaches.

The first graph shows the number of total tests conducted by countries as of July the 5th 2020. At this point, the United States had tested more than 34 million people, the largest number of tests conducted by a single country so far. Other countries with limited health resources and testing capacity, such as Nigeria and Indonesia, had only tested around 100 000 to 500 000 people despite having large populations.

However, the absolute number of tests conducted may not itself provide an insightful picture on how countries are implementing testing strategies. The figure on the right shows the total number of tests conducted per 1000 people. As you can see, the U.S. has conducted fewer tests per 1000 people compared to Russia. While counting cases of disease appears to be straightforward, there are also issues to consider when enumerating disease counts during an epidemic. For instance, as highlighted by the previous slide, case definitions can vary significantly across countries. Hubei province in China for example, changed the case definition from laboratory confirmed cases, to clinically confirmed cases in February 2020 and then subsequently back again, which affected how many official confirmed cases were reported.

According to the WHO, a confirmed case is a person with laboratory confirmation of COVID-19 infection, irrespective of clinical signs and symptoms. The degree of testing across countries also depends on other several factors. Many countries are targeting specific population groups for testing. The U.S for example, applied an initially narrow classification in deciding the target population of those who had recently traveled to China, or had contact with suspected cases. In March 2020, the CDC expanded this criterion to anyone with signs or symptoms of COVID-19, regardless of their travel history. The CDC also then recommended testing asymptomatic individuals with recent exposure, What then followed, was a surge in case findings. Other countries have been quicker and more aggressive in testing the broader population.

South Korea tested a large part of its population within days of the outbreak, while Iceland managed to test an even higher percentage of its population. Both of these countries have now managed to control the spread of the disease. Testing techniques also matter. Starting from the types of biological samples collected, and the timing of the sample collection, down to the reliability of the testing kits, and capacity of the laboratory. For instance, upper respiratory tract samples such as nose or throat swabs may offer lower diagnostic value compared to samples taken from the lower respiratory tract Blood specimens, which are collected mostly for rapid diagnostic tests, could also be used to test the genetic sequence of the virus.

As the reliability of these testing approaches and their prioritization for use varies, this would also affect the number of positive cases reported. Different kits are also known to have varying levels of test sensitivity and specificity, which may lead to variations of false positive and false negative between labs and countries

To turn now to look at some more specific country comparisons in testing approaches. As of July 2020, Vietnam has seen a total of 355 cases and has had zero deaths from COVID-19. Timely response has been a major contributor to Vietnam’s successful response so far In January, when the country recorded two cases, the government swiftly planned for worst case scenario. It then imposed restrictions, mass testing, and contact tracing at four levels.

Confirmed COVID-19 patients and their direct contacts as level 1, close contact with level 1 where all contacts were isolated in quarantine facilities as level two, those in close contact with level two population, were then self-isolated at home as level three, and a lockdown of the neighborhood where the patient lives was enacted as level four. This also meant that each new patient led to high targeted testing numbers. The ability of the government in Vietnam to perform ambitious and aggressive contact tracing, was connected to strong government control over population mobility. A mobile app was also released to alert the authorities about suspected cases in specific areas.

Important background context is that Vietnam has been preparing for an epidemic following the 2003 SARS pandemic, by establishing a clear command line, ensuring personal protective equipment was available, and supply chains were effective, and giving the military a central role in mobilizing resources and assisting with quarantine measures. This provides a good example of effectively learning from a past health major health emergency, to improve pandemic preparedness and response. Other countries such as Sweden were slow in testing their populations. There were no clear guidelines on how to define and prioritize testing. Initially, Sweden limited testing to healthcare staff and hospital inpatients, and many people even with symptoms of COVID-19 had difficulties accessing the test.

In May 2020, Sweden finally decided to expand testing to people with mild symptoms. However, the containment measures were too late. Now Sweden has more COVID-19 deaths per capita than most European countries and its COVID-19 death rate, that is the number of coronavirus deaths divided by the total number of cases, is one of the highest in the world. 11 percent of people confirmed to have COVID-19 infection in Sweden have died, compared to six percent in the U.S and five percent in Germany. Another differing example is Australia, where initially everyone with recent travel history and symptoms was tested. Later on, Australia expanded its testing strategy to included anyone with mild symptoms and conducted rigorous contact tracing.

The COVIDSafe mobile app was also launched to provide information on possible transmission based on geolocation of the population. While a large and significant portion of the population has downloaded the app, the extent to which is this has been useful in actual contact tracing isn’t clear. We’ve learned that community participation is important in epidemic control, which has already been discussed a number of times this week. One of the ways to do this is through participatory disease surveillance, which is an innovative tool for surveillance of communicable diseases, in which citizens are actively engaged in the self-reporting of symptoms or events to help public health experts aggregate and analyze data for appropriate public health intervention.

India is an example where PDS has been implemented through this pandemic. The Aarogya Setu mobile app serves as a tool for contact tracing, syndromic mapping, and digital self-assessment The initial focus was in urban area hotspots, and it relied on volunteers that would feed information through the app. However, a clear limitation with the approach exists in large rural or poor areas, where people may not have access to the internet, or the technology required to utilize the app. Now that we’ve looked at some reasons for the variation of testing and tracing across different country contexts, we will build on this by exploring through a quiz why case numbers may have been comparatively lower in Africa.