SARS-CoV-2 variants: global risk and experience for Vietnam

Tuesday, 2021-07-20 17:33:06
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Taking samples for COVID-19 testing in Ho Chi Minh City. (Photo: Diem Hang)
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NDO – Over a year and a half since it was discovered, the SARS-CoV-2 virus that causes COVID-19 has caused four global outbreaks around the world and there has been a dominant variant in each outbreak.

With thousands of recorded variants, scientists are under great pressure analysing these and preparing response scenarios as the virus becomes increasingly complex.

A virus that can cause a global pandemic must spread easily from person to person. During the early stages, the SARS-CoV-2 virus spread slowly and only through droplets, close contact and indirect contact via surfaces. In order to cause a pandemic, the virus had to mutate so that it could be easily transmitted from person to person as well as can spreading in the so-called pre-symptomatic stage, shown to be the more dangerous stage of SARS-CoV-2 for the community.

Existing variants of this virus include the B.1.1.7 (Alpha) , first discovered in the UK and then spread through the world but which has been gradually replaced by the Delta variant. The B.1.351 variant (Beta), found in South Africa in December 2020, was thought to reduce the protective effectiveness of vaccines. The P.1 (Gamma) strain was discovered in early January this year and circulated strongly in Brazil. The B.1.617.2 (Delta) variant, found in India in late 2020, quickly became dominant and spread globally, threatening to erase epidemic prevention and control efforts in many countries. This variant currently accounts for most of the infections in Vietnam. In addition, the C.37 mutation (Lambda) appeared first in Peru in December 2020 and accounted for 82% of new cases in the country , thereafter spreading to around 24 nations, mainly in South America. In the last two months, it has spread at a high rate and has been cited by the World Health Organisation (WHO) as a kind of concern.

The increase in the infection rate does not mean the epidemic is more dangerous. Currently, vaccines seem to reduce the ability to prevent infections caused by the virus but their capacity to protect against severe illness and hospitalisation is still very good. However, these variants have quickly become the majority since they appeared. The jump in the number of COVID-19 cases has overloaded the medical system and is indirectly leading to increased mortality.

Like other RNA viruses, SARS-CoV-2 has no error-control mechanism when it replicates. As a result, there will be a wrong/broken model in its genetic code during each 1,000 copies. If this error makes sense, it will create a new version of the virus and if that mutation makes it easier to spread, it will spread and quickly replace the previous one. Accordingly, a new variant is formed.

The proliferation of strains requires scientists to carefully study them while soon detecting new versions. A new variant needs to be evaluated as to whether it is more contagious or not; whether it causes milder or more severe illness; if it can be detected with current tests or not; if it responds to current treatment modalities; and can it alter the protective efficacy of the vaccines or not. In Japan, viral sequencing tests have been done regularly and reports of virus mutations have been posted weekly for early warning purposes.

Thailand offers free Covid-19 testing for people. (Photo: Reuters)

Countries with poor epidemic control are a prime environment for virus variants. This is the reason why many countries, including the UK, South Africa, Brazil and India, were banned from flying following the reports of variants. However, the prohibition has often come too late as new strains have already penetrated the target countries. Accordingly, the whole world must join hands to control the epidemic. Vietnam has been highly lauded by the world thanks to its drastic actions to prevent and control the pandemic.

Some other countries and territories were also praised, including Taiwan (China) with its effective isolation and tracing strategies; Singapore with a smart management, tracing and vaccination system; the Republic of Korea with its capacity for total testing, tracing and tracking cases; New Zealand with its management of quarantine areas and freezing of high-risk zones; and Australia with its limited short-term closures and blockades.

Recently, many people have mentioned the severe acute pneumonia syndrome (SARS) that swept the world in 2003 and the MERS epidemic in 2012. Despite being controlled and disappearing, the corona virus that caused SARS mutated and is able to spread easily from person to person. SARS-CoV-2 has become the virus causing the pandemic as it is difficult to predict. A routine practice during the outbreaks has been the monitoring of the genetic mutation of the virus by genetic sequencing. With current results, it is difficult to predict when this virus will become a seasonal flu that humans can live with. This has not happened yet and people have made great efforts to control it.

Some opinions from foreign experts say the appearance of the Delta variant will put an end to Vietnam's luck. Actually, the statement that Vietnam was lucky during the previous outbreaks is not entirely accurate. To gain success, the Party, State and Government took prompt and drastic action as well as making strong commitments related to epidemic preparedness. The Ministry of Health, other ministries and agencies and localities are again implementing many measures to respond to the epidemic. Drastic measures have been conducted such as the establishment of a central tracking teams in coordination with thousands of tracing officers at all levels throughout the country.

In addition, the most unique feature is the active participation of community-based COVID groups. This is a centipede-foot-shaped network and extension arm of epidemic prevention and control designed to detect cases of intrusion as early as possible as well as symptomatic cases in the community.

Besides strengthening community surveillance, test-based surveillance is indispensable. The continuous monitoring and detection of new strains has been also assigned to research institutes so that any significant intrusion or mutation will be controlled and monitored, thereby making an important contribution to the overall success of the virus control strategy in Vietnam.

Dr. Pham Quang Thai