RESULTS

Among 1497 fully vaccinated health care workers for whom RT-PCR data were available, 39 SARS-CoV-2 breakthrough infections were documented. Neutralizing antibody titers in case patients during the peri-infection period were lower than those in matched uninfected controls (case-to-control ratio, 0.361; 95% confidence interval, 0.165 to 0.787). Higher peri-infection neutralizing antibody titers were associated with lower infectivity (higher Ct values). Most breakthrough cases were mild or asymptomatic, although 19% had persistent symptoms (>6 weeks). The B.1.1.7 (alpha) variant was found in 85% of samples tested. A total of 74% of case patients had a high viral load (Ct value, <30) at some point during their infection; however, of these patients, only 17 (59%) had a positive result on concurrent Ag-RDT. No secondary infections were documented.

CONCLUSIONS

Among fully vaccinated health care workers, the occurrence of breakthrough infections with SARS-CoV-2 was correlated with neutralizing antibody titers during the peri-infection period. Most breakthrough infections were mild or asymptomatic, although persistent symptoms did occur.

Don't let the 'perfect be the enemy of the good'. Only a fool concisously increases risk for no reward.

Yeah, you can be infected, infect other after vacination. One is likely to have less severe illness, lesser viral load and infect fewer if you're vaccinated.

Yes, 'omicron' is a mutation of earlier virus and can, like them stll infect the vaccinated. This  variety of 'Trump Flu' seems m,ore contagious but less severe than Delta, other mutations. There will be more strains in the future, this virus went from a few cases to world-wide in about a year and several mutations. 

Under Trump America became the most infected in the world and maintains that base of infection. Once it's out it's out to spread. This will be with us forever, humanity will develop resistance to existing and new mutations will enter the population from animal reservoirs (like white tail deer).

 

A health worker administering a dose of the Pfizer Covid-19 vaccine earlier this year in Jerusalem.

PHOTO: ABIR SULTAN/EPA/SHUTTERSTOCK

By Dov Lieber

 

Updated Dec. 12, 2021 2:21 pm ET

 

TEL AVIV—A booster shot of Pfizer Inc. PFE 5.14% and BioNTech SE’s BNTX 9.45% Covid-19 vaccine provides good protection against severe illness from the Omicron variant, while those without a third shot are highly vulnerable, according to a new Israeli study.

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The findings, similar to those announced last week by Pfizer, suggest countries worried about Omicron’s rapid spread will be able to defend their populations with continued inoculation.

Researchers at the Sheba Medical Center and from the Israeli Health Ministry examined the blood samples of 20 Sheba employees who received a booster at least a month ago, and 20 employees who are five or six months past their second shot and haven’t received a third shot.

Employees with a booster were much more likely to neutralize the Omicron variant than the two-shot group, the study showed. But the booster shots were still less effective against preventing Omicron than other variants, including Delta, still the most prevalent strain of the virus circulating globally.

 

Why Omicron’s Complex Mutations Could Change the Pandemic's Outlook

Why Omicron’s Complex Mutations Could Change the Pandemic's Outlook

Early data already suggest that the Omicron variant may be better at evading vaccine-generated antibodies, and a lot of that has to do with what’s happening at a molecular level. WSJ’s Daniela Hernandez explains.

The study’s takeaway: Individuals who received boosters may be more likely to be infected with Omicron than other variants, but they will be unlikely to develop severe illness or be hospitalized, said Gili Regev-Yochay, director of the infectious-disease epidemiology unit at Sheba Medical Center, in a news conference Saturday night.

 

The study’s bad news, said Dr. Regev-Yochay, is that people who got a “second dose of the vaccine five to six months ago don’t have any neutralizing ability.”

“If you’re past five months and didn’t get a booster, go get it,” Dr. Regev-Yochay said.

Those in the two-shot group still showed some protection against the Delta variant. The findings will soon be published in the New England Journal of Medicine. The study was based on a few dozen blood samples, Dr. Regev-Yochay said, calling it a “relatively nice size” for such a study.

Last week Pfizer said a third dose of its vaccine increased antibodies against Omicron 25-fold compared with two doses.

The studies by Israeli researchers and Pfizer, and one by scientists in South Africa, where the Omicron variant was first detected, suggest that three doses will be needed to produce the effective immune response against Omicron that was provided by just two doses against earlier virus strains.

The Israeli study’s authors said their effort was the first to combine a real sample of the Omicron variant grown in a lab with blood samples from individuals who received a booster shot. The Pfizer research was conducted on a pseudovirus meant to mimic the real one.

Pfizer and BioNTech are working on an Omicron-specific vaccine that they hope to have available by March 2022 if the variant becomes widespread by then. Researchers started working on the new vaccine on Nov. 25, shortly after Omicron was identified.