Is the "4th dose" effective against Omicron? Israeli study says benefits may be 'minimal'
The local epidemic broke out again on March 27. Not only were 83 new cases confirmed in a single day, but as many as 120 cases were imported from abroad. The epidemic seemed to be on the rise. This situation also makes people think, should the “fourth dose” be included as one of the future epidemic prevention policies? Israel, known for its rapid vaccination efficiency, took the lead in administering the fourth dose to medical staff in January this year. The results showed that the benefits of the fourth dose of the vaccine may not be as great as everyone imagined.
The fourth dose makes antibodies in the body “10 times more”? Is 3 injections enough to achieve “immunogenicity”?
A research team from the Israeli Ministry of Health published the results of the fourth dose of vaccine administered to medical staff in the New England Journal of Medicine (NEJM). After medical staff administered the two mRNA vaccines, Moderna and Pfizer-BNT, data showed that the two vaccines made the neutralizing antibodies in the recipients 9-10 times higher, but the increase in neutralizing antibodies was not the same as the first. The difference between the three doses was very small, and there was no significant difference between the two vaccines.
In terms of side effects, research shows that although most vaccinated people have asymptomatic symptoms such as fever, muscle aches, nausea, dizziness, etc., most of them are mild and do not lead to substantial adverse reactions. Compared with the vaccination and the third dose, the side effects did not become more obvious, or were more mild.
The research team pointed out that the fourth dose of BNT had 81.7% protection against Omicron virus; the fourth dose of Moderna had 79.3% protection. The total protection against any new coronavirus variant (such as Delta, Alpha) is 30% for BNT and 11% for Moderna.
Based on the above, studies have proven that the fourth dose of the mRNA vaccine has immunogenicity, safety and certain antiviral efficacy. The protection for symptomatic infections is also significantly increased (43% for BNT and 31% for Moderna). However, the immune response to the fourth dose in the vaccinee was not significantly different from the immune response at the peak of the third dose; this also means that the maximum immunogenicity of the mRNA can be achieved by administering three doses of the vaccine.
The benefit of dose 4 to young people is “minimal”? Is it difficult to end the epidemic with constant “additional doses”?
The Israeli Ministry of Health believes that for healthy young medical practitioners, a fourth vaccination may have only “minimal” benefits.
“When faced with Omicron, those who are relatively young, healthy and without a history of chronic disease may not benefit from a fourth dose,” said study author Gili Regev-Yochay.
Still, Regev-Yochay noted that the fourth dose may be beneficial for groups at higher risk of severe disease. For example, the elderly, patients with chronic diseases, etc. The Israeli Ministry of Health also released preliminary statistics, showing that for people over 60 years old, the protection of the fourth dose of the vaccine is approximately twice that of the third dose.
Although the study’s statistical results are based on a small sample size and there are uncertainties, the fourth dose of the vaccine may still have an effect on certain groups. However, Regev-Yochay believes that constantly adding more doses will hardly be a solution to ending the pandemic.
“We are still waiting for the advent of the ‘flu shot’. Only when the virus becomes influenza and humans coexist with it can we hope to end the epidemic,” Regev-Yochay said.
source:
Fourth dose of COVID vaccine offers only slight boost against Omicron infection
Efficacy of a Fourth Dose of Covid-19 mRNA Vaccine against Omicron
Further reading:
The number of asymptomatic infections has “increased at least 6 times”. Intensivist: Omicron has made “the whole world relax”
