Why asymptomatic testing is crucial to curb the silent spread

Amit Chopra, MD India and South Asia, Thermo Fisher Scientific explains that the only way to stop rapid transmission is to enable large scale testing that can control outbreaks before they happen

India is witnessing a more intense second wave of COVID-19.  While the speed to market the vaccines has been unprecedented, it will still be months before the vaccines are available to most people.  Contrary to popular perception, vaccines do not completely prevent people from becoming infected with a disease. Based on existing data, the current COVID-19 vaccines confer excellent effective immunity, but do not provide complete immunity against the SARS-CoV-2 virus. This means that a vaccinated person who contracts COVID-19 may not know they are infected – but they may still be able to transmit the disease.  Further, concerns remain about the emergence of new variants that could evade the protection conferred by the vaccines. Hence, identifying them and modifying the vaccines also requires testing.

Why is asymptomatic testing crucial?

Asymptomatic transmission is a significant source of spread, and if left undetected, an asymptomatic patient can continue to be a host for spreading the virus. If there are multiple asymptomatic people in a chain of transmission, it becomes extremely difficult for government organisations to trace back the source of the virus through contact tracing methods. This can result in a ‘silent’ spread where the virus continues to proliferate undetected. While this can remain hidden for days, it can lead to a large outbreak. The only way to stop rapid transmission is to enable large scale testing that can control outbreaks before they happen.

Typically, people with higher viral loads of the virus would exhibit more severe symptoms. Conversely, asymptomatic cases would have lower viral loads. Hence, testing methods have to be sensitive enough to detect even lower concentrations of the virus. PCR based testing is believed to be the most reliable and sensitive method that is available today. It is important that institutions and communities’ partner with laboratories or third-party service providers that can deliver results within a day or less, so that decisive actions can be taken quickly to further prevent infections from spreading.

Large scale community-based testing of asymptomatic people can be beneficial in making people aware of the infection, isolation and curb further transmission. This also helps in improving the effectiveness of contact tracing, as it allows public health officials to quickly determine the chain of transmission. Testing asymptomatic patients can give us a more accurate picture of the spread of the virus, allowing government and healthcare systems to be better prepared.

Overall, the scientific and medical communities have rallied together to develop therapies and vaccines at an accelerated pace. As vaccines are being deployed on a priority basis, the need for routine surveillance testing strategies for SARS CoV-2 infection has emerged as a vital tool in monitoring population-level occurrences. Testing combined with complementary safety protocols, continue to be the most effective measure to navigate through these challenging times.

asymptomatic testingCOVID-19 testingPCR based testing
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