The Federation of Thai Industries (FTI) expects the third wave of Covid-19 to cause losses of around 100 billion baht to the manufacturing sector, prompting automakers to adjust their car production targets for this year.
The outbreak, which began earlier this month, will affect factories, especially those supplying the tourism and service markets, said the federation.
People are fixated on virus spread, staying at home and restricting travel to avoid the disease, said the FTI.
As a result, spending looks set to decline as infections exceed 2,000 a day, with the death toll rising to 15 on Tuesday, setting a new daily record for the third time in four days.
"The third wave is bad for the domestic economy, especially tourism and service businesses," FTI chairman Supant Mongkolsuthree said on Tuesday.
Thailand has only a few economic boosters, including exports, which showed signs of growth based on a global economic recovery driven by the US and China, he said.
The urgent issue for Thailand is administering Covid-19 vaccines at a rapid speed, said Mr Supant.
The government and the Joint Standing Committee on Commerce, Industry and Banking are scheduled to meet today to discuss plans for vaccinations, after the state was criticised for progress at a snail's pace.
If the government can administer 20-30 million doses to people by June, it could prevent further economic loss and help affected businesses get back on track, said Mr Supant.
Factories and petrol stations are willing to help provide more vaccination venues.
"Workers can receive vaccines at their factories or workplaces, which usually hire nurses," he said.
The Thailand Industry Sentiment Index in March rose from 85.1 to 87.3 points, but the finding was based on a survey of 1,351 companies in 45 industries between March 5 and April 9 before the pandemic hit the whole country, said the FTI.
Surapong Paisitpatanapong, vice-chairman and spokesman for the FTI's automotive club, said the club is considering adjusting its 2021 car manufacturing target as the industry is facing the impact of the third outbreak and a global semiconductor shortage.
It previously expected to see a 5.1% increase in car production to 1.5 million units, half of which would be exports.
Car exports from Thailand in March increased by 31.5% year-on-year to 104,506 units, the highest level since the pandemic hit, according to the club.