Omicron thwarts some of the world’s most-used COVID vaccines

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A man in Javanese traditional dress receives a dose of the Sinovac COVID-19 vaccine at a temple in Yogyakarta, Indonesia. Credit: Ulet Ifansasti/Getty

The world’s most widely used COVID-19 vaccines provide little to no protection against infection with the rapidly spreading Omicron variant, laboratory evidence suggests.

Inactivated-virus vaccines contain SARS-CoV-2 particles that have been chemically treated to make it impossible for them to cause an infection. Stable and relatively easy to manufacture, such vaccines have been distributed widely as part of China’s global vaccine diplomacy, helping them to become the jab of choice in many countries. But a multitude of experiments show that they are consistently hobbled by Omicron.

Many people who receive two jabs of an inactivated vaccine fail to produce immune molecules that can counter Omicron transmission. And even after a third dose of an inactivated vaccine, an individual’s levels of ‘neutralizing’ antibodies, which provide a potent safeguard against viral infection of cells, tend to remain low. A third shot of another type of vaccine, such as those based on messenger RNA or purified proteins, seems to offer better protection against Omicron.

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