Costa Rican scientists developing rapid Covid-19 saliva test

San Jose, Jan 26 (efe-epa).- Costa Rican scientists are developing a rapid molecular saliva-based test for Covid-19 that promises to give that Central American country a certain degree of autonomy and allow it to conduct mass contact tracing.

A score of experts from three public higher-learning institutions – University of Costa Rica (UCR), Technological of Costa Rica (TEC) and National University of Costa Rica (UNA) – have finalized the first prototype of saliva tests for the rapid diagnosis of the SARS-CoV-2 virus in symptomatic and asymptomatic patients.

“It’s rapid because it takes one hour, it’s low-cost (between $15 and $20), sophisticated equipment isn’t needed to amplify the genetic material. And that would put Costa Rica in an advantageous situation because it would allow it to epidemiologically trace (the spread of) the virus on a mass scale,” the project’s coordinator, UCR biology professor Andres Gatica, said in an interview with Efe.

The RT-LAMP test, known in Costa Rica as ticovid-19 (Costa Ricans are affectionately known as “ticos”), complements the most widely deployed RT-PCR test (a molecular test that detects the virus’ genetic material) and reduces the risk of infection among health workers because samples can be self-collected and no special means of transportation are required.

Alejandro Bolivar, a researcher at UCR’s Pharmacy School, said the saliva sample is collected in a vial and heated to 95 C (203 F) to amplify possible traces of the virus. This allows the test result to be obtained without the need for molecular biology laboratories or other specialized equipment.

Through the testing process, the sample undergoes a color change and will turn yellow if the virus is present and red if the result is negative.

The Costa Rican saliva test still must undergo a human trial phase to measure its effectiveness, a process that will require permits from that country’s Committee on Scientific Ethics.

“With the in vitro tests we’ve performed we have 94 percent specificity (the proportion of negatives that are correctly identified) and 100 percent sensitivity (the proportion of positives that are correctly identified), figures that are quite positive, very comparable to real-time PCR and far superior to the antigen test that detects proteins and antibodies if a person became ill and developed defenses,” Gatica said.

Saliva tests are already in use globally to detect the presence of the coronavirus, some of which have been approved by the United States Food and Drug Administration.

Costa Rica and several regional countries such as El Salvador, Guatemala and the Dominican Republic are now working together to develop the technical and scientific capacities needed to make this test a reality.

“They (the other countries) have an advantage that we don’t have. They can already work with saliva tests on patients. We still don’t have the permits,” Gatica said.

Costa Rica, a country home to 5 million inhabitants, has registered 191,345 confirmed coronavirus cases and 2,567 deaths attributed to Covid-19 since the start of the pandemic, numbers that yield a case fatality rate of approximately 1.3 percent. EFE-EPA


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