NARATHIWAT: A civilian defence volunteer alerts people to lockdown measures including the curfew introduced to halt the spread of the COVID-19 coronavirus in the southern province of Narathiwat, as Thailand faces a surge in cases of the virus. — AFP

BANGKOK: Thailand yesterday defended mixing two different COVID-19 vaccines to battle a surge in infections, after the WHO's top scientist warned it was a "dangerous trend" not backed by evidence. The kingdom is struggling to contain its latest outbreak fuelled by the highly contagious Delta variant, with cases and deaths skyrocketing and the healthcare system stretched thin.

Authorities said they will mix a first dose of the Chinese-made Sinovac jab with a second dose of AstraZeneca to try and achieve a "booster" effect in six weeks instead of 12. Thailand's chief virologist Yong Poovorawan said this would be possible by combining an inactivated virus vaccine-Sinovac-with a viral vector vaccine such as AstraZeneca.

"We can't wait 12 weeks (for a booster effect) in this outbreak where the disease is spreading fast," he said. "But in the future, if there are better, improved vaccines... we will find a better way to manage the situation." His comments come a day after the World Health Organisation's chief scientist Soumya Swaminathan called the strategy a "dangerous trend".

"We are in a bit of a data-free, evidence-free zone as far as 'mix-and-match'", she said. Thailand has reported more than 353,700 coronavirus cases and 2,847 deaths-the bulk of them detected since the latest wave kicked off in April from an upscale Bangkok nightlife district.

Healthcare workers were the first in line to receive Sinovac, but authorities said Sunday nearly 900 medical staff-most of them vaccinated with that shot-got COVID-19. They will now also get an AstraZeneca or Pfizer-BioNTech booster shot, authorities said. Virus hotspot Bangkok and nine other hard-hit provinces are now under tougher restrictions that include a night-time curfew and a ban of gatherings over five people.

Meanwhile, the developers of Russia's Sputnik V coronavirus vaccine said yesterday a deal had been struck with Indian vaccine maker the Serum Institute to produce 300 million doses annually. "The parties intend to produce over 300 million doses of the vaccine in India per year with the first batch expected in September 2021," the Russian Direct Investment Fund (RDIF) said in a statement.

Sputnik V was registered by Russia in August last year-the first of four vaccines developed in the country-and the RDIF says it is approved for use in 67 countries. Its hasty development and distribution for use ahead of late-stage trials meant the jab was initially greeted with scepticism.

Sputnik V has since won over experts, in a scientific and geopolitical victory for President Vladimir Putin, who announced late last month he had been inoculated with the vaccine. Kirill Dmitriev, the CEO of RDIF, described the deal with Serum as "a major step" that would increase Sputnik V production capabilities and ultimately "save lives both in India and around the world".

He said that technology transfer had begun and joint production was expected to start in the coming months. Serum Institute CEO Adar Poonawalla said in the statement that since it had shown "high efficacy and a good safety profile, it is critical that the Sputnik vaccine is accessible in full measure for people across India and the world." In January, the RDIF, which helped finance Sputnik V, announced that it had applied for registration of the vaccine in the European Union. - AFP