Symptoms associated with COVID-19 are changing, as the virus has evolved over the three years since the initial Wuhan outbreak, according to Dr. Yong Poovorawan, head of the Centre of Excellence in Clinical Virology at the Faculty of Medicine of Chulalongkorn University.

The symptoms which have changed are as follows:

The incubation period of the Omicron variant has shortened to approximately three days, compared to the longer period for the Delta variant.

There are fewer lung infections, which means less severe symptoms.

Fewer cases of anosmia.

Thermal screening devices, installed at most public venues, cannot detect Omicron variant infection because the fever in an infected person will last only 1-2 days. Many who are infected do not have fever, although many develop muscle pains.

The most obvious symptom is a severe sore throat.

Easy transmissibility. When a person is infected, the whole family is likely to become infected, compared to the initial stage of the pandemic when adults were the most likely to get infected. Now, children are more susceptible to infection, but most develop mild symptoms and can easily spread the disease to other people.

The disease has a tendency to spread seasonally, like flu or influenza. In the northern hemisphere, like in Europe and America, outbreaks usually occur in winter, from November to March. In the southern hemisphere, like in Australia and New Zealand, from June to September. In Thailand, which is in the tropical zone, outbreaks will occur during the rainy season.

COVID-19 is constantly mutating, like influenza, hence, the greater chance of reinfection, but symptoms are less severe, except in high-risk groups of people. Therefore, the vaccines must be more specific to the virus variants or sub-variants to be effective and they must be administered before there is an outbreak, especially for young children and vulnerable groups of people, known collectively as the “608 group”.

Source: Thai Public Broadcasting Service