Pfizer’s coronavirus vaccine protection against Omicron disappears weeks after second and third doses


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A peer-reviewed study published in Pfizer and BioNtech found that immunity to the Omicron coronavirus variant rapidly disappears after second and third doses of Pfizer and BioNtech’s Covid-19 vaccine. JAMA Network Open on friday, Findings that could support distributing additional booster shots to vulnerable people as variants drive an increase in new cases across the country.

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A Danish study of 128 people with two to three doses found that after 2nd and 3rd doses of Pfizer injections, levels of omicron-specific “neutralizing” antibodies that could target the virus and prevent replication were lowered. decreased sharply.

Antibody levels associated with protection against infection and disease fell within weeks of injection and were well below antibody levels against the original and delta coronavirus strains, the researchers said.

Compared to the original and delta variants, the proportion of omicron-specific antibodies detected in the participants’ blood dropped “rapidly” from 76% 4 weeks after the second injection to 53% at 8-10 weeks and 19% at 12-14 weeks. I lost. Researcher found.

Omicron-specific antibody levels increased after the third dose, almost 21-fold at week 3 and nearly 8-fold at week 4, compared to 4 weeks after the second dose, with injections giving most people a detectable response for at least 8 hours was seen. A few weeks later, the researchers said.

However, antibody levels began to drop 3 weeks after booster injection, dropping 4.9-fold for the original variant, 5.6-fold for delta, and 5.4-fold for Omicron between 3 and 8 weeks.

A “transient” antibody response after two or three doses means that additional additional injections may be needed to combat the variant, particularly among older adults, the researchers said.

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Experts and regulators widely acknowledge the benefits of a third vaccination to enhance protection against serious illness and death. Beyond that, there is little consensus on whether additional shots are needed, and the question arises whether frequent boosting is practical. Neutralizing antibodies have been a major focus of research evaluating vaccines, and while they are much easier to study, they are not the only part of the immune system that protects humans from disease. Other parts of the immune system, such as T cells, May be less effective at preventing infection, but are more durable than antibodies and reduce Possibility of serious illness if infected. Many experts believe that this latter property is a major function of vaccination, not prevention of infection, and the data suggests that it provides much more durable protection, including those against omicrons.

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