Israel Finds Fourth COVID Booster is only ‘Partially Effective,’ Vast Majority of Hospitalised Omicron Patients Are Unvaccinated
An Israeli woman gets a COVID-19 vaccine.

A fourth COVID-19 booster mRNA vaccine has proven ineffective against Omicron infection, according to preliminary research from Israel released on Monday.

“Despite a significant increase in antibodies after the fourth vaccine, this protection is only partially effective against the Omicron strain, which is relatively resistant to the vaccine,” lead researcher Prof Gili Regev-Yochay, told a media briefing on Monday.

Some 154 health workers at Sheba Medical Center received their fourth Pfizer shot two weeks ago. A week ago, 120 healthworkers received a shot of Moderna following three doses of Pfizer one week ago.

They were matched with a control group of around 6,000 health workers who have been being followed by the hospital since the start of Israel’s vaccination campaign in December 2020. 

According to Regev-Yochay, the third dose resulted in “much higher antibodies, neutralization and the antibodies were not just higher in quantity but also in quality” than the second dose – but the fourth vaccine did not show  significant antibody increase.

”Maybe there are a few more antibodies but not much more compared to the third dose,” said Regev-Yochay.

Last week, she told Israeli Prime Minister Naftali Bennett that there had been a five-fold increase in antibodies in people who took the fourth dose, but she later told a radio station that “the amount of antibodies returns to the level it was after the third vaccine, not more. It’s nice, but it’s not what we expect from a booster.”

In addition, around the same percentage of hospital workers who received the fourth dose caught the virus as those who didn’t get the fourth booster. 

Booster demand may affect global supply

Meanwhile, the European Medicines Agency (EMA) cautioned last week that there was no evidence to back a fourth booster, warning that repeat boosters every four months might actually weaken people’s immune systems.

Boosters “can be done once, or maybe twice, but it’s not something that we can think should be repeated constantly,” said Marco Cavaleri, the EMA head of biological health threats and vaccines strategy, said at a press briefing last week, as reported by Bloomberg.

Instead, the agency recommended that boosters should be tied to the cold season with longer intervals.

The World Health Organization (WHO) has also warned repeatedly against boosters while a high percentage of people in low and middle-income countries – estimated to be over 40% of the world’s population – are unvaccinated, fearing boosters will lower the number of vaccine doses available to these countries.

“With near- and medium-term supply of the available vaccines, the need for equity in access to vaccines across countries to achieve global public health goals, programmatic considerations including vaccine demand, and evolution of the virus, a vaccination strategy based on repeated booster doses of the original vaccine composition is unlikely to be appropriate or sustainable,” the WHO said on 11 January.

Vast majority of Omicron patients in hospitals are unvaccinated

Meanwhile, the latest research from South Africa, New York City and California show that the vast majority of people hospitalised by the COVID-19 Omicron variant are unvaccinated – but that they still experienced less severe disease than those infected with Delta.

South Africa reported that around 82% of those hospitalised during its Omicron-fueled fourth wave were unvaccinated.

Hospital statistics of over 128,000 patients with Delta and almost 35,000 patients with Omicron, showed those with Omicron fared significantly better than those with Delta. 

In the Delta group, 26.4% of patients, 14.6% were admitted to ICU and 63% had severe disease.

South Africa Omicron vs Delta, NICD January 2022

In comparison, only 9.7% of those with Omicron died, while 5.8% were admitted to ICU and 31.7% had severe illness, according to a presentation by the National Institute of Communicable Diseases delivered at a media briefing hosted by South African Department of Health last Friday.

A similar trend was reported by the New York City (NYC) Health Department, which reported that about 2% of Omicron cases were hospitalised in comparison to around 5% of Delta cases.

About half the proportion of NYC hospitalized patients required intensive care during the Omicron wave compared to the peak of the winter 2020-2021 wave – about 11% versus about 20%, according to a NYC health department report released late last week. 

“In NYC, those most likely to be hospitalized are people who are not vaccinated, and a higher proportion of Black New Yorkers and people age 75 and older were hospitalized,” according to the report.

“New Yorkers who were not vaccinated were more than eight times more likely to be hospitalized compared to New Yorkers who were fully vaccinated, early in the Omicron wave. Differences in health outcomes among racial and ethnic groups are due to long-term structural racism, not biological or personal traits,” it added.

In addition, a pre-print study of COVID-19 cases in southern California compiled by Kaiser Permanente of over 52,000 Omicron infections and almost 17,000 Delta infections, found 0.5% of hospital admissions for Omicron patients and  1.3% for those infected with the Delta variant.

Rates of ICU admission from Omicron patients were 0.26 fold those of Delta, while mortality for Omicron patients was 0.09 fold that of Delta patients.

No Omicron patients received mechanical ventilation in comparison to 11 Delta patients, and Omicron patients stayed in hospital on average 3.4 days less than Delta patients.


Image Credits: Maccabi Health Services, Clalit Health Fund .

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