"Department of Disease Control" confirms that currently no evidence indicates "COVID-19" variant NB.1.8.1, the main strain spreading in the country, shows increased severity compared to previous variants.
On 3 June 2026, Dr. Montien Kanasawat, Director-General of the Department of Disease Control, stated that the department under the Ministry of Public Health continuously monitors the COVID-19 situation and changes in the SARS-CoV-2 virus variants through the Digital Disease Surveillance system (DDS), event surveillance, and laboratory monitoring. Current data show no signs indicating that the NB.1.8.1 variant causes disease severity different from previously circulating variants.
According to the DDS data as of 2 June 2026, there were 4,156 COVID-19 cases and one death. The age group with the highest case count was 30–39 years old, followed by those aged 60 and over, and then 20–29 years old.
Over the past month, although seasonal case reports have risen, the number of patients remains below the five-year median. Variant surveillance data from the Department of Medical Sciences between 1 January 2025 and 23 April 2026 show that NB.1.8.1 is the predominant variant in Thailand, accounting for 50.95%, followed by JN.1 at 24.97%, and XEC at 9.14%. The NB.1.8.1 variant has been continuously detected and spreading since mid-2025.
The Director-General added that although NB.1.8.1 has mutations that enhance transmissibility and immune evasion, epidemiological and clinical data currently provide no evidence that it causes more severe symptoms or a higher risk of death than earlier variants. Most patients exhibit symptoms similar to common respiratory infections, such as fever, cough, sore throat, and runny nose.
Thailand maintains a continuous respiratory infection and pathogen variant surveillance system through a network of 26 sentinel hospitals nationwide. This covers key respiratory diseases, including COVID-19, influenza, and other respiratory viral infections. Samples from patients meeting surveillance criteria are systematically tested, and if abnormal signals or significant pathogen changes relevant to public health are detected, further analysis is conducted by the Department of Medical Sciences to identify variants and assess risks in depth. This system allows Thailand to promptly monitor and detect unusual pathogen changes.
The surveillance system in Thailand continues to operate by monitoring patient numbers, outbreak events, and viral variant tracking to enable rapid and appropriate public health risk assessment and response.
Dr. Direk Khamphaen, Deputy Director-General of the Department of Disease Control, noted that current surveillance shows no signs of widespread outbreaks or increased disease severity beyond past seasonal trends. However, COVID-19 remains a respiratory infection that can appear year-round, especially during the rainy season when people gather more in enclosed spaces.
The Department of Disease Control advises the public to maintain good personal hygiene, wash hands frequently, wear masks in crowded places or when experiencing respiratory symptoms, avoid close contact with the sick, and if experiencing fever, cough, sore throat, or runny nose, to conduct initial screening and avoid close contact with vulnerable groups such as the elderly, people with chronic diseases, and pregnant women to reduce the risk of severe illness. For further information, the public can contact the Department of Disease Control hotline at 1422.