Article Notes
- Analysis of 927 confirmed symptomatic cases of COVID-19 demonstrates BNT162b2 is highly effective with 91.3% vaccine efficacy observed against COVID-19, measured seven days through up to six months after the second dose.
- Vaccine was 100% effective in preventing severe disease as defined by the U.S. Centers for Disease Control and Prevention and 95.3% effective in preventing severe disease as defined by the U.S. Food and Drug Administration.
- Vaccine was 100% effective in preventing COVID-19 cases in South Africa, where the B.1.351 lineage is prevalent.
- Vaccine safety now evaluated in more than 44,000 participants 16 years of age and older, with more than 12,000 vaccinated participants having at least six months follow-up after their second dose.
This reassuring study published in Nature by researchers from Wash U Med investigated persisting COVID immunity following the Pfizer mRNA vaccination (BNT162b2). Turner et al. looked at the presence of not only circulating antibody-secreting B cells, but also germinal centre B cells found in the axillary lymph nodes of 14 study volunteers.
While the persistence of mRNA-vaccine induced immunity to SARS-CoV-2 has already been demonstrated to last at least 6 months, and likely 12 months, we just do not yet have the data to know if or when vaccine boosters will be required beyond that.
Turner's study is particularly exciting because they found spike-protein binding B cells in the germinal centre of draining lymph nodes in all 14 post-immunisation participants for the full 15 weeks of the study. The germinal centre response was so vigorous and persistent that the researchers believe this could represent COVID-protection lasting for years.
"Ellebedy said the immune response observed in his team’s study appears so robust and persistent that he thinks that it could last for years. The researcher based his assessment on the fact that germinal centre reactions that persist for several months or longer usually indicate an extremely vigorous immune response that culminates in the production of large numbers of long-lasting immune cells, called memory B cells. Some memory B cells can survive for years or even decades..." – Dr Francis Collins, NIH Directors Blog
This study builds on the same team's earlier work (Turner 2021 May) looking at bone marrow plasma cells in those who have recovered from mild COVID infection, also showing a long-lived immune response.
COVID persistent immunity takeaway:
Although COVID-19 and developed vaccines have been circulating for only 12-18 months, these immune-response studies give some hope that the miracle of mRNA vaccines may not only be in their efficacy, but also in the longevity of protection.
Pfizer and BioNTech reported that phase 3 trials of their mRNA SARS-COV-2 vaccine showed:
Although interesting and perhaps relevant to settings which require motor block resolution before discharge from PACU (or when there are bupivacaine shortages), the practical relevance of this study is questionable.
Notable in this French study is the extended duration of PACU stay after caesarean section: more than 2 hours in the prilocaine group, and 3 hours in the bupivcaine group! It is unclear whether this is routine post-CS care, or specific to the study design to allow for motor block assessment.
Also of note, the caesarean sections were "...performed using Misgav-Ladach technique with externalisation of the uterus" which may again make this study less relevant in settings where it is routinely accepted that avoiding uterine externalisation makes for better patient experience.