Thailand to Follow Sinovac With Astra Vaccine in World First

Thailand will start administering the Sinovac Biotech Ltd. and AstraZeneca Plc shots as part of one Covid-19 vaccine regime, in a world first aimed at increasing protection against the more contagious delta variant.

The Southeast Asian nation will start giving the China-made Sinovac vaccine as a first shot to be followed by Astra three to four weeks later, health ministry officials said at a briefing near Bangkok Monday.

The decision is based on three separate local studies, which showed that following Sinovac with Astra elicited an immune response that’s as high as using two doses of Astra 12 weeks apart, according to Opas Karnkawinpong, director-general of Thailand’s Department of Disease Control. The new regime will allow the nation to quickly ramp up immunity against the delta variant, Opas said.

Thailand to Follow Sinovac With Astra Vaccine in World First

While countries from the U.K. to U.S. have been studying interchanging vaccines to address shortages and better combat new virus mutations, Thailand’s adoption of it as a state policy follows reports of hundreds of health workers getting infected even after being inoculated with Sinovac shots. The country is battling a flareup in infections that’s triggered lockdown-like measures in greater Bangkok area and other virus hotspots. It’s also seen snags in supplies, particularly of the Astra vaccine.

In one of the studies, preliminary results showed that a first dose of Sinovac followed by an Astra shot three to four weeks later can elicit an immune response that’s eight times stronger than two doses of the Sinovac vaccine, according to Yong Poovorawan, chief of the Center of Excellence in Clinical Virology at Chulalongkorn University.

To date, Thailand has administered 12.6 million doses of vaccine, 56% of which are Sinovac, 43% are Astra, and 1% are Sinopharm shots.

Thailand to Follow Sinovac With Astra Vaccine in World First

Thai health officials also backed a plan to administer booster doses of Pfizer Inc. and Astra shots to its health workers, who are already fully inoculated with Sinovac shots. The country has ordered 20 million doses of Pfizer and is set to receive 1.5 million doses as a donation from the U.S.

Sinovac, which was criticized for the varying efficacy rates thrown up in clinical trials of its shots, has said little publicly about how its shot performs against delta. Astra, which is a viral vector vaccine, is 60% effective at preventing symptomatic infections caused by the variant that first emerged in India, a study has shown, though it can still prevent more than 90% of hospitalizations.

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