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Fourth COVID shot has little effect on Omicron infection: study

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A fourth dose of the existing mRNA COVID-19 vaccine may have “small benefits” for young and healthy adults, according to a new Israeli study published Wednesday. New England Journal of Medicine..

The study evaluated 270 healthcare workers who received a second booster dose of the Pfizer or Moderna vaccine four months after receiving the Pfizer vaccine three times at the Sheva Medical Center in Tel Aviv. ..

Each matched the ages of the two participants Control group With only three doses of Pfizer, the median age of the group ranged from mid-50s to early 60s.

Overall, the fourth injection is safe and comparable to the recipient’s neutralizing antibody, which blocks coronavirus from infecting cells, immediately after the third dose, before antibody levels begin to decline over time. Replenished up to.

Studies were conducted during the spread of the Omicron variant in Israel, and despite the decrease in antibodies over time in people who received only three injections, the fourth dose provided much stronger protection against infection. I found that it wasn’t.

People who received a fourth injection of Pfizer were 30% less likely to get infected than those who took three doses, while those who got Moderna were 18% less likely to get infected. ..

This study included only a small number of participants and was not a randomized trial. That is, the conclusions need to be interpreted with caution, but the results show only a small benefit from additional doses.

Defensive protection against symptomatic infections was slightly better in the fourth jab recipient of adults under the age of 40 (43% in Pfizer, 31% in Moderna).

The authors of a study led by Gili Regev-Yochay write that their study appears to show the benefits of three doses. vaccination Designed for the original strain of coronavirus, it has reached its upper limit in terms of immune response, and additional boosters only restore weakened immunity rather than raising it to new heights. did.

“In addition, the low vaccine efficacy against infections by health care workers and the relatively high viral load indicate that infected individuals are infectious. Therefore, a fourth vaccination of healthy young people. health care worker You may only get a small profit. “

External experts said the findings indicated the need to develop a new vaccine.

“If Omicron continues to circulate and is still using the current 1st generation COVID-19 vaccine against it, I agree with the author. Young people Julian Tan, a clinical virologist at the University of Leicester, said.

“The fourth boost is more beneficial for the elderly and more. Vulnerable group (For example, a person with comorbidities), “he continued.

“Ideally, if you want to improve this defense against the most vulnerable people, just like updating the seasonal flu vaccine every year, to ensure the best match with what is currently on the market. Requires a new COVID-19 vaccine specifically designed for Omicron. Influenza. ”


Pfizer urges the United States to allow seniors to receive a fourth COVID vaccine


© 2022 AFP

Quote: 4th COVID shot has little effect on Omicron infection: Survey (March 16, 2022) https: //medicalxpress.com/news/2022-03-fourth-covid-shot-benefit -Obtained March 16, 2022 from omicron.html

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Fourth COVID shot has little effect on Omicron infection: study

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