World Health Organization reports insufficient evidence to support syndromic screening for COVID-19

By Nidhi Saha, BDSDec 28 2022Reviewed by Aimee Molineux

According to a scientific brief by the World Health Organization (WHO), there is insufficient information to implement syndromic coronavirus disease 2019 (COVID-19) testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission prevention across land borders.

Background

Since the outbreak of the COVID-19 pandemic, over 651 million cases and 6.6 million deaths have been reported worldwide. The cumulative infection and death rates associated with the COVID-19 pandemic are probably underestimated due to a lack of adequate testing and infection data from around the world. 

Researchers, health officials, and diagnostic companies have joined forces worldwide to understand the SARS-CoV-2 virus better, protect communities from outbreaks, and develop robust diagnostic tests to address these problems. SARS-CoV-2 diagnostic tests are being devised, but syndromic testing is particularly important in combating the pandemic.

The term "syndromic testing" refers to using one test to target multiple pathogens with overlapping signs and symptoms. This may comprise testing for temperature and pulmonary or other complaints, observation, and completion of health statement documents. Before the COVID-19 outbreak, syndromic testing was applied for other communicable diseases such as Ebola virus disease, respiratory infections such as pandemic H1N1, and plague.

Questions have been raised over the preventive potential of syndromic testing on COVID-19 transmissibility among travelers. Also, illegal land trespassing and open borders hamper any intervention used to curb the spread of COVID-19 and other infectious diseases, particularly in the setting of a global crisis.

In this scientific brief, the authors assessed the effectiveness of syndromic testing in containing the spread of COVID-19 at border crossings and transboundary river crossings. This study aimed to examine the effect of COVID-19 syndromic departure and entry screening of travelers crossing land borders utilizing the PICO question (Population, Intervention, Comparison, Outcome).

The study 

A systematic review was conducted to resolve the PICO question. Based on the GRADE methodology (Grading of Recommendations, Assessment, Development, and Evaluation), evidence was classified as high, moderate, low, or extremely low in terms of quality.

 An external systematic review team assessed the validity of the research using the Newcastle-Ottawa Scale (NOS). Data were analyzed, and findings were established by the WHO International Travel and Health Guidelines Development Group (ITH GDG). The research found seven empirical studies published between 2020 and January 2022 that investigated the utility of COVID-19 screening at border crossings.

A retrospective cross-sectional study in Uganda examined the effectiveness of syndromic screening records collected from 7,181 truck drivers who traveled to Uganda through Mutukula, in the United Republic of Tanzania – from 15 May to 30 July 2020.

The findings

In a cross-sectional retrospective study conducted in Uganda, thermal screening failed to detect COVID-19 infections at border crossings. The number of cases detected by the tests varied significantly across the seven investigations, ranging from 2.2% to 43.6%. Insufficient data was found to support or refute the claim that syndromic screening is associated with health risks. Therefore, the WHO concluded that there is inadequate data to support syndromic testing for COVID-19 at border crossings.

In addition, traveling through unorganized and informal border crossings can circumvent checkpoints complicating the evaluation of the intervention's effectiveness. Of note, considering the currently circulating SARS-CoV-2 variants, syndromic testing can be ineffective in some countries. Furthermore, screening might give travelers and neighbors a false sense of security. 

It was also noted that communication across countries and states and extensive coordination among the participating nations are essential for appropriately interpreting and using screening strategies. For individuals with disabilities, syndromic screening may adversely affect access to healthcare providers and caregivers.

Moreover, there is an urgent need for investigations comparing the efficacy and success of syndromic screening versus testing, quarantine, and other public health and social interventions, as well as syndromic screening in conjunction with other health measures.

Limitations

In this brief, there are several limitations, including a small number of studies (only seven investigations), early pandemic investigations, data stratification, and a lack of scientific knowledge. As a result of these limitations, future active surveillance, and study approaches, which separate the effects of syndromic screening techniques, are necessary.