(Bloomberg) -- Thailand has detected its first local case of a delta plus sublineage less than a week before a planned nationwide reopening for vaccinated international visitors. 

One case of delta subtype AY.1 was reported in the northern province of Kamphaeng Phet, while 18 cases of alpha plus, which has been spreading in neighboring Cambodia, have been reported in three provinces, Supakit Sirilak, director-general of the Department of Medical Sciences, said on Tuesday. 

The local delta plus case was found in a patient at a field hospital by the Armed Forces Research Institute of Medical Sciences, he said. Thailand has so far detected 19 delta subtypes, and AY.30 is the most common with more than 1,300 cases, Health Ministry data showed. 

AY.4.2 sublineage, which was designated a Variant Under Investigation by the U.K. Health Security Agency, still hasn’t been detected in Thailand, and health officials will continue to collect more samples and investigate cases, Supakit said. 

“The emergence of new variants is common during an outbreak, and it’ll be a significant occurrence if the variant is more infectious, lead to more severe cases, or more resistant to vaccines,” said Deputy Health Minister Satit Pitutecha. “At this point, there’s still no cause for concern, and authorities will monitor the situation closely.”

Thailand is set to allow vaccinated visitors from 46 jurisdictions to enter the country without a mandatory quarantine from Nov. 1 as it loosens travel curbs to restart its struggling tourism industry. The country saw new Covid cases drop to 7,706 on Tuesday, the lowest one-day tally since early July. 

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