Meanwhile, the US Centers for Disease Control and Prevention (CDC) on Thursday recommended COVID-19 booster shots from Pfizer and Moderna targeting the Omicron variant, clearing the way for the administration of the shots.

This new generation of anti-Covid vaccines targets both the original strain of coronavirus and the BA.4 and BA.5 lineages, the subvariants of Omicron that are causing the most cases in the United States.

The Pfizer-BioNTech shot is recommended for people 12 and older and Moderna's for those 18 years and up.

"The updated Covid-19 boosters are formulated to better protect against the most recently circulating Covid-19 variant. They can help restore protection that has waned since previous vaccination and were designed to provide broader protection against newer variants," CDC Director Rochelle Walensky said in a statement.

"This recommendation followed a comprehensive scientific evaluation and robust scientific discussion," she added.

The new versions of the vaccines -- which were approved by the US Food and Drug Administration on Wednesday -- could potentially be available in the United States as early as next week.

The vaccines currently in circulation target the initial strain of the virus that first appeared in Wuhan, China. But they have gradually proven to be less effective against the variants that have appeared over time, due to rapid evolution of the virus. 

In contrast to the Alpha and Delta variants, which eventually waned, Omicron and its subvariants have come to dominate infections worldwide in 2022.

Popular

The fragile promise of pluralism, religious freedom in Southeast Asia

Coffee, gold push up inflation to 1.95 percent in April

Furniture exporters decry new quarantine rule