Health authorities are closely monitoring reports of new mutations that could significantly increase the ability of the JN.1 variant of Covid-19, now becoming dominant in Thailand, to evade people’s immune systems.
About 40 cases of JN.1 have been detected, but none with the so-called slip mutations first reported in France recently, according to the Department of Medical Sciences (DMS) at the Ministry of Public Health.
JN.1 is a variant of the Omicron strain of the SARS-CoV-2 virus. Since the beginning of 2022, the DMS and a network of laboratories have been monitoring a number of Omicron variants and sub-variants, said Dr Yongyot Thamwut, the department’s director-general.
The World Health Organization (WHO) has identified 10 Omicron strains based on data showing increased prevalence or faster rates of spread. Five including JN.1 are so-called Variants of Interest and five are Variants under Monitoring.
The first “slip mutations”, or mutations at two positions, were reported recently in France, with 41 confirmed cases identified worldwide as of Jan 15.
Dr Yongyot said that among the VOI group overall, global data as of Dec 3 showed the EG.5 variant the most prevalent with 36.3% of reported cases, followed by JN.1 with 27.1%. The detection rate for EG.5 was shown to be falling while that of JN.1 was rising over the last 28 days of the survey period.
The hybrid strain XBB.1.16 was the main strain spreading in Thailand early in 2023, overtaken by XBB.1.9.2 in September. Results of laboratory tests conducted from November to Jan 15 showed XBB.1.9.2 decreasing while JN.1 was increasing.
The JN.1 strain was first detected in Thailand on October and was seen to be increasing in prevalence in December, overtaking XBB.1.9.2. People infected with JN.1 have been found in many areas of the country, with generally mild symptoms such as fever, cough and phlegm, but no deaths have been reported, Dr Yongyot said.
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