Fourth dose of COVID-19 vaccine triples protection for people over 60s: Israel

Israel’s Sheba Medical Center finds second booster is not enough to prevent transmission of Omicron variant

A person using a syringe to draw vaccine dose from a vile — Reuters
A person using a syringe to draw vaccine dose from a vile — Reuters

Administering a fourth dose of the coronavirus vaccine to people over 60 years of age in Israel made them three times more resistant to serious illness in comparison to people who received three jabs, Israel’s Health Ministry said.

The ministry’s analysis was based on a trial where 400,000 people in Israel over 60 were administered a fourth shot and 600,000 a third booster shot.

Also, a study by Israel’s Sheba Medical Center has found that a second booster, or the fourth dose of the vaccine, increased antibodies, but it was still not enough to prevent the transmission of the Omicron variant.

Similar studies in Germany, South Africa and the United Kingdom have echoed the findings of the research that the approved vaccines are less effective against Omicron but boosters increased protection, reported Haaretz.

Omicron was first designated as a variant of concern by the World Health Organization on November 26.

Omicron 'sub-variant' throws up new virus questions

Scientists are keeping a close watch on a recently-discovered sub-variant of the Omicron version of the COVID-19 virus to determine how its emergence could affect future pandemic spread.

The initial Omicron variant has become the dominant virus strain in recent months but British health authorities have notably identified hundreds of cases of the latest version, dubbed BA.2, while international data suggest it could spread relatively quickly.

The UK Health Security Agency (UKHSA) identified more than 400 cases in Britain in the first ten days of this month and has indicated the latest variant has been detected in some 40 other countries, accounting for a majority of most recent cases in some nations including India, Denmark and Sweden.

The UKHSA indicated Friday it had designated the BA.2 sub-lineage as a variant under investigation (VUI) as cases of it were on the increase even if, in Britain, the BA.1 lineage currently remains dominant.

The authority underlined that "there is still uncertainty around the significance of the changes to the viral genome," which required surveillance as, in parallel, cases in recent days showed a sharp rise in BA.2 incidence notably in India and Demark.

"What surprised us is the rapidity with which this sub-variant, which has been circulating to a great extent in Asia, has taken hold in Denmark," French epidemiologist Antoine Flahault told AFP.

Scientists must evaluate how the virus, which has engendered the worst global health crisis in a century, continues to evolve and mutate. Its latest incarnation does not possess the specific mutation used to track and compare BA.1 against Delta, the previously dominant strain.

BA.2 has yet to be designated a variant of concern — but Flahault says countries have to be alert to the latest development as scientists ramp up surveillance.

"(France) expected a spike in contaminations in mid-January: It didn't happen and perhaps that is due to this sub-variant, which seems very transmissible but not more virulent" than BA.1, he observed.

"What interests us is if this (sub-variant) possesses different characteristics" from BA.1 in terms of contagiousness and severity, France´s public health agency said Friday.

To date, only a handful of BA.2 cases have emerged in France — but the country is monitoring developments as they spread across the Channel.