"Booster Shot Can't Prevent Omicron 'Infection'... Possible to Prevent Severe Cases and Death"

South African Researchers Analyze 7 Cases of Omicron Breakthrough Infections

Omicron.
Photo by Yonhap News

[Asia Economy Reporter Na Ye-eun] A study has found that even with additional doses (booster shots) of messenger RNA (mRNA)-based COVID-19 vaccines such as Pfizer and Moderna, protection against infection by the Omicron variant remains weak.

However, the vaccines were shown to be effective in preventing severe illness and death caused by COVID-19.

According to Bloomberg News on the 19th (local time), researchers from the University of Cape Town and Stellenbosch University in South Africa analyzed seven German researchers who contracted COVID-19 while visiting Cape Town, the capital of South Africa, during the early emergence of Omicron from late November to early December last year, revealing these findings.

All seven German researchers who participated in the study had received booster shots but experienced symptomatic breakthrough COVID-19 infections. They reported respiratory symptoms, but all symptoms were mild.

The researchers stated, "This study suggests that Omicron can evade immunity formed even after booster shots," and emphasized, "Even if vaccinated, it is necessary to continue response measures such as social distancing and wearing masks."

They added, "Strong T-cell responses were detected in the study subjects," indicating that "receiving booster shots provides protection against severe disease caused by Omicron."

T cells, a type of white blood cell, remember past diseases, kill virus-infected cells, and activate antibodies to coordinate defense mechanisms. Their activity is enhanced when vaccinated, which is one of the various immune responses triggered by vaccine administration.

However, the researchers stressed, "Ultimately, better vaccines will be needed to prevent Omicron infection itself."

Meanwhile, the ages of the study subjects ranged from 25 to 29 years old. Five were female and two were male, none were obese, and none had a history of COVID-19 infection.

Among the subjects, five received three doses of the Pfizer vaccine, one completed vaccination with Moderna and then received a Pfizer booster, and another received AstraZeneca (AZ), a viral vector vaccine, for the first dose followed by Pfizer for the second and booster doses.