The BMA rushed to test the workers at the construction camp in Lak Si last Friday before detecting high infection rates among them. Credit: BMA

First local cases of contagious Indian variant discovered among construction workers in Lak Si

The Public Health Ministry is rushing to investigate the virus transmission among construction workers in a construction camp in Lak Si area, where some 36 Thai and migrant workers have been infected with the variant so far

The lab results from the Medical Sciences Department have been released this late afternoon and they have shown that out of 80 samples taken from construction workers at the construction camp, 36 have been infected with the sub-lineage of the Indian variant, or B.1.617.2. 21 of them are Thais, 10 are Burmese, and five are Cambodians.

Dr. Suppakij Sirilak, the department’s chief, said over 87% of Covid-19 transmissions in the country now is the UK variant of B.1.1.7. As the new variant has been found, the department would immediately extend its testing to other clusters to see the distribution of this variant, he said.

Based on the Public Health England, which has been monitoring the variants in the UK, the Indian variant spreads relatively as fast as the UK’s, but no evidence shows it causes severe Covid-19 infections or deaths, Dr. Suppakij said. In addition, the variant is still responsive to the Covid-19 vaccines, he added but did not elaborate which vaccines he meant to while allaying public concerns by saying people should not be worried about it too much.

The Department of Disease Control’s chief Dr.Opas Karnkawinphong has also stepped out to allay public concerns during the press briefing in the afternoon, citing the experiences from the UK, where both variants are found to have been contracting the citizens there.

The DDC chief said the Indian variant causes impacts similar to the UK one; not spreading faster, nor causing more severe Covid-19 infections. Moreover, the AstraZeneca vaccine, which Thailand will adopt as the priority choice, can help control its outbreaks there, he added.

The workers got Covid-19 tests last week before a large number of them were found having been infected with the virus. Credit: BMA

Dr. Opas said the department has still had no clues how it has arrived in local settings. Previously, the variant was detected only in imported cases and placed under quarantine.

Dr. Opas said the Indian variant has spread in several countries including neighbouring countries like Malaysia and Singapore. Myanmar and Cambodia, he added, would have had testing limited, but it is believed that the variant would also have spread there. So, it could slip into the country, but to tell exactly how needs the DNA testing to help compare genetic codes of the variants here with those of the neighbouring countries along with the epidemiological probes, he said.

So far, those infected with the variants are being treated similarly to other Covid-19 patients, and they are having just mild symptoms, he said.

Infections of Covid-19 among construction workers in construction sites in Bangkok were first reported shortly after the clusters in communities, which had emerged during late April and the first week of the month. The cluster in Lak Si since has been among the top clusters under close watch by the authorities as the new infections keep rising over the week and the infection rate is relatively high, over 80%.

In addition, the workers were found in contact with residents in communities nearby. At least six communities nearby were identified as having been close or in contact with the workers, and there are over 6,000 residents there, who are now placed under surveillance too.

The construction camp in Lak Si is among those under close watch as there is an inclining trend of the outbreak there. Credit: BMA

As of Wednesday, the Bangkok Metropolitan Administration reported that out of 1,667 construction workers plus some contacts, or 3,671 of them altogether, were tested, and 1,107 of them were found to have been infected with the virus.

The Center for COVID-19 Situation Administration’s spokesperson Dr. Taweesin Visanuyothin said of the situation that a large number of infections among construction workers there was partly due to their cramped and crowded environment.

The company owner was asked to implement disease control measures in the site, while the disease control officials have planned to conduct active case finding in other construction camps nearby, around eight of them, as well as in the said communities.

Credit: WHO

The Indian variant

The Indian variant has become a public concern since infections in India extensively surged over the past few months, eventually sending it to the world’s 2nd in terms of confirmed cases, which is only after the United State. The country’s surge of cases has also sent the world’s record of new weekly cases to the new peak, with nearly 5.7 million recorded in the fourth week of April, the World Health Organisation (WHO) said, adding that 38% of this peak was from India.

From early January last year to today, 26.03 million cases have been reported in India, with 291,331 deaths, according to WHO.

The overall counts of new weekly cases have just slightly declined in the past two weeks, but still, India has contributed the largest numbers. As of May 16, over 2.38 out of 4.80 million cases recorded worldwide were from India, during which the world’s cumulative cases were over 162 million with 3.36 million deaths already.

WHO has recently moved up the status of the Indian variant, from the variant of interest to the variant of concern.

“In consultation with the WHO SARS-CoV-2 Virus Evolution Working Group, WHO has determined that viruses within the lineage B.1.617 have been characterized as a VOC,” WHO’s weekly publication on Covid-19 update, on May 11, noted.

According to WHO, B.1.617 has three sublineages. They “differ by few but potentially relevant mutations in the spike protein as well as the prevalence of detection globally”, the world’s public health organisation noted.

While the available evidence is too limited to characterize a sublineage, the organisation further noted that it has designated B.1.617 as a VOC based on “early evidence of its phenotypic impacts” or observable traits, compared to other circulating virus variants.

WHO then noted that B.1.617 sublineages “appear to have higher rates of transmission”, including observed rapid increases in prevalence in multiple countries (with moderate evidence available for B.1.617.1 and B.1.617.2.).

The preliminary evidence suggests potentially reduced effectiveness of a monoclonal antibody, or a cloned antibody, used for COVID-19 treatment, and potentially slightly reduced susceptibility to neutralisation antibodies (with the limited evidence available for B.1.617.1), it said.

B.1.617 lineage was first reported in India in October 2020. Case and deaths then have resurged during the second wave, raising questions on its potential role along with the others such as the UK’s, WHO noted.

Based on its recent risk assessment of the situation in India, WHO found that resurgence and acceleration of COVID-19 transmission there had several potential contributing factors, including an increase in the proportion of cases of Covid variants “with potentially increased transmissibility”, several religious and political mass gathering events which increased social mixing, and underuse of and reduced adherence to public health and social measures.

However, WHO said the exact contributions of each of these factors on increased transmission in India are not yet well understood. Approximately 0.1% of positive samples in India have been sequenced and uploaded to GISAID to identify variants, it said.

As of May 18, B.1.617.2 have been detected in 48 countries and territories, B.1.617.1 (41), and B.1.617.3 (5), according to WHO.

Countries and territories reporting three sublineages of the Indian variant and an unspecified sublineage, as of 18 May 2021. Credit: WHO