Findings from a small study of eight patients published in Clinical Infectious Diseases suggest that COVID-19 rebound is likely not caused by impaired immune responses. The study, led by scientists at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, aimed to define the clinical course and the immunologic and virologic characteristics of COVID-19 rebound in patients who have taken nirmatrelvir/ritonavir (Paxlovid), an antiviral therapeutic developed by Pfizer, Inc. COVID-19 rebound is characterized by a recurrence of COVID-19 symptoms and/or a new positive viral test after having tested negative, according to the Centers for Disease Control and Prevention. According to the study authors, the results do not support the hypothesis that the five-day course of Paxlovid is too short for the body to develop a strong immune response to SARS-CoV-2, the virus that causes COVID-19.
The next question is do we need a 4th Omicron booster? Where are the studies showing repeated infections in the 3rd booster group vs the 4th booster group? The short time periods do not allow for the true degradation (if any) of the immune response to a 4th generation omicron booster.
The rush to re-vaccinate may be premature. Hopefully, the development of a whole virus vaccine is in process. There has been enough time to do so using conventional vaccine production. We should not lose sight of the original rush to produce the vaccine using a relatively unproven new mRNA process. which has been shown to produce a more limited length of an immune response.
What do the new boosters contain?
A bit of the old and a bit of the new. Both the Pfizer-BioNTech collaboration and Moderna make their vaccines from messenger RNA (mRNA) coding for the spike protein of SARS-CoV-2. The new vaccines are bivalent. Half of the mRNA codes for the spike protein of the ancestral virus strain that emerged in Wuhan, China, in late 2019, which is also in the original shots; the other half codes for the spike protein in BA.1 or the one in BA.4 and BA.5, which have identical spikes. Because they contain a lower dose of mRNA, the shots are meant to be used as boosters only, and not in people who were never vaccinated.
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