Nearly 65% of the positive cases during Viet Nam's COVID-19 waves are asymptomatic and 29% have mild clinical symptoms, thus posing an added challenge to the nation's contact tracing and screening efforts, the Treatment Subcommittee under the National Steering Committee for COVID-19 Prevention and Control reported that.

On July 14, the Ministry of Health issued Decision No. 3416/QD-BYT guiding the diagnosis and treatment of COVID-19 caused by the SARS-CoV-2, identifying common symptoms as fever, dry cough, fatigue, muscle pain, sore throat, vomiting and diarrhea; whilst some patients display olfactory disturbance or tongue numbness and others show no clinical symptoms. Therefore, it is hard to detect asymptomatic people infected with the virus via only the screening and temperature measurement measures.

Because of no clinical symptoms, the infected person still participates in daily activities in the community as usual, resulting in a high risk of contagion.

The Ministry of Health has issued documents directing medical facilities to conduct screening and periodic tests for SARS-CoV-2. However, in the community, the implementation of such screening tests is really a matter of concern, because of high costs and depending on the conditions and capacity of the healthcare sector.

Given the new strain of SARS-CoV-2, the asymptomatic cases make detection difficult, especially because even Covid-19 tests fail to identify positive cases during the first few tries, making contact tracing “exceedingly difficult”. Therefore, body temperature measurement in service for the COVID-19 detection which has been applied in agencies, units and businesses is no longer effective for the time being.

According to researchers, the virus's incubation period could last up to 21 days, with symptoms typically showing up on days 5-12. From day 15-21, very few symptoms are seen, if any.

In most patients, the symptoms are mild and would typically clear up after about a week. But severe cases mean trips to the ICUs, ventilators and increased risk of death.

Some of the recent COVID-19 cases in Da Nang were detected via the patients' self-examination and emergency at medical facilities. Since then, epidemiological investigations and screening tests are conducted to track down the primary and secondary contacts. This means that COVID-19 is quietly spreading in the community.

Therefore, it is necessary to accelerate the implementation of plans and solutions, with a focus on conducting COVID-19 testing for many times on groups of high-risk and random subjects in the community.

Along with that, timely contact tracing, quarantine and isolation must be implemented in a prompt fashion, thus minimising the risk of coronavirus infections.

Reporting by ANH QUAN – Translating by A.T