Govts push for 3rd jab to battle Omicron, but questions remain

HONG KONG • The Omicron variant of the coronavirus has triggered a global rush for booster shots, as scientists and governments see a third dose as the most expedient strategy against the new strain that appears to cause a marked loss of vaccine protection.

In the days after earliest findings showed that Omicron caused a 25-to 40-fold loss of neutralising antibodies from the Pfizer-BioNTech vaccine, the United States has expanded booster access to teenagers while countries such as Britain and South Korea are slashing wait times for a third dose by half, to three months.

More are certain to follow.

BioNTech founder Ugur Sahin said this week that the mRNA shot "should be a three-dose vaccine" to fight the new strain, and that the third dose could come as early as three months after the second.

But questions remain over whether the rush to booster is the right strategy against Omicron.

The World Health Organisation has stressed that the world must work to ensure vaccine access for those yet to receive their first doses before richer governments roll out boosters to the general population.

That is the only way to prevent more new strains, it said.

News that two Omicron cases in Singapore had already received third shots affected the financial markets this week.

Researchers also caution that the science has yet to definitively show that shorter intervals for boosters than the current six-month norm create higher immune protection.

"There is no data yet on whether they are needed three or six months after; there could be a difference," said University of Hong Kong virologist Jin Dong-Yan.

Complicating matters is emerging evidence that boosters given later rather than sooner could be more potent when it comes to inactivated vaccines like the one made by China's Sinovac Biotech.

A study in the Lancet medical journal this week found that the increase in protective antibodies from Sinovac's vaccine was significantly muted for those getting a third dose as soon as two months after the second, compared with those getting it after eight months.

Despite the lingering uncertainty, the gap between the unvaccinated and the boostered is already widening.

In the US, fully vaccinated people are lining up for third shots while the US Centres for Disease Control and Prevention extended access to 16-and 17-year-olds this week.

Yesterday, South Korea revised downwards the interval for booster shots to three months as one of Asia's most-vaccinated countries grapples with a double whammy of record infections and the detection of Omicron among patients.

British Prime Minister Boris Johnson also promised to slash the six-month wait time between second and third doses by half next week amid signs that Omicron is spreading among Britons.

Vietnam's government has announced a target to give boosters to the entire population in the first six months of next year, though fewer than 60 per cent of its population are currently fully vaccinated.

In India, which has not yet started a third-dose campaign, with only 36 per cent of its population having received two doses, medical associations are calling for boosters for front-line health workers.

Given the fear that Omicron may reverse the world's efforts to emerge from the pandemic, the booster race is likely only to accelerate in the coming weeks.

"Fully vaccinated will mean three doses," said Dr Jin. "That will likely become the universal requirement across governments around the world."

BLOOMBERG