The army admitted on Monday that it was impossible to completely seal Thailand's borders from illegal migrants, even as the Public Health Ministry confirmed the latest infection cluster at a shrimp market in Samut Sakhon was linked to migrant labourers.
"Illegal migrant labourers are still crossing the border using natural channels, even though we have deployed a legion of soldiers to guard the demarcation. Our border is 5,526 kilometres long," said deputy army chief-of-staff and army spokesman Lt Gen Santipong Thammapiya.
He admitted illegal migrants were still sneaking into Thailand from Myanmar, especially at highly porous locations in Tak, Chiang Rai and Kanchanaburi. The army, he said, would add even more resources, including drones, mobile patrol units and razor-wire fences to secure high-risk areas.
The army had recently arrested 279 Myanmar nationals at vulnerable border crossings in those three provinces and had already sent them back, said Lt Gen Santipong.
In addition, 200 soldiers were recently sent to Samut Sakhon, the flash-point of the latest Covid-19 infection cluster, to boost the authorities' screening and checkpoint capacity, he added.
Meanwhile, Dr Vichan Pawun, director of the Institute for Urban Disease Control, said that migrant workers in Samut Sakhon could be the cause of the latest infections at the central shrimp market in Muang district.
Dr Vichan said the institute's epidemiological analysis had found that Myanmar migrant workers might indeed be the source of the outbreak that has alarmed the government.
That assumption, Dr Vichan said, was based on the latest Covid-19 tests, which had found 90% of infected people were Myanmar migrant workers living in that area. The institute has started a genetic analysis of Covid-19 viruses in these patients to establish the source and time each patient was infected.
He attributed the cluster infection to the fact that migrant workers lived in crowded rooms with sub-par sanitary standards and rarely wore face masks.
The number of confirmed Covid-19 patients from the Samut Sakhon cluster had reached 821 by last night. The vast majority -- 788 -- were migrant workers and the other 33 were Thais.
The Public Health Ministry tested 4,688 people in the province over the weekend and will complete testing the 5,612 others it deemed to be at risk today.
Dr Vichan said that that the possible infection rate was 42% among those living in the "egg yolk" zone -- the shrimp market and adjacent communities -- but only 6% for those living beyond that zone.
If the infection rate among those living further afield remained at 6% and was seen to be dropping, he forecasts that the Samut Sakhon outbreak would be brought under control within a month.
Dr Vichan also said the Public Health Ministry was administering Covid-19 tests to Myanmar migrant worker across the country.
Meanwhile, Labour Minister Suchart Chomklin said his staff would today ask the Social Security Board to release funds so both Thai and foreign migrant workers in registered factories and workplaces in Samut Sakhon could be tested too.
The money will go towards paying 50% compensation to people who need to take time off work to be tested.
Mr Suchart says the budget will cover 160,000 tests and will be targeted at both Thai workers in the province and legal migrant workers who hold Social Security Fund cards. He did not say exactly how much money would be requested, but estimated the cost at 3,000 baht per head.
He said his ministry would stop bringing in migrant labour from neighbouring countries but this won't affect companies as there are 2.3 million legal migrant workers.