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rate of severe infections (ISR), which we define as infections resulting in hospitalization or out-of-hospital death, and the rate of critical infections (ICR), which we define as infections resulting in critical care admission or out-of-ICU death

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In conclusion, we presented the first estimates of age-specific ISR and ICR of SARS-CoV-2 using multi-country serology data. Our estimates show that, as with other SARS-Cov-2 outcomes, the ISR and ICR increased exponentially with age; however, the rate of increase in the risk of severe and critical disease outcomes with age is less marked than the rate of increase in lethality due to SARS-Cov-2 infection.

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SARS-CoV-2 variant B.1.617.2 (delta) is associated with higher viral loads 1 and increased transmissibility relative to other variants, as well as partial escape from polyclonal and monoclonal antibodies 2. The emergence of the delta variant has been associated with increasing case counts and test-positivity rates, indicative of rapid community spread. Since early July 2021, SARS-CoV-2 cases in the United States have increased coincident with delta SARS-CoV-2 becoming the predominant lineage nationwide 3. Understanding how and why the virus is spreading in settings where there is high vaccine coverage has important public health implications. It is particularly important to assess whether vaccinated individuals who become infected can transmit SARS-CoV-2 to others. In Wisconsin, a large local contract laboratory provides SARS-CoV-2 testing for multiple local health departments, providing a single standard source of data using the same assay to measure virus burdens in test-positive cases. This includes providing high-volume testing in Dane County, a county with extremely high vaccine coverage. These PCR-based tests provide semi-quantitative information about the viral load, or amount of SARS-CoV-2 RNA, in respiratory specimens. Here we use this viral load data to compare the amount of SARS-CoV-2 present in test-positive specimens from people who self-report their vaccine status and date of final immunization, during a period in which the delta variant became the predominant circulating variant in Wisconsin. We find no difference in viral loads when comparing unvaccinated individuals to those who have vaccine “breakthrough” infections. Furthermore, individuals with vaccine breakthrough infections frequently test positive with viral loads consistent with the ability to shed infectious viruses. Our results, while preliminary, suggest that if vaccinated individuals become infected with the delta variant, they may be sources of SARS-CoV-2 transmission to others.

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Six Month Safety and Efficacy of the BNT162b2 mRNA COVID-19 Vaccine
Preprint doi: https://doi.org/10.1101/2021.07.28.21261159


Abstract
Background BNT162b2 is a lipid nanoparticle-formulated, nucleoside-modified RNA vaccine encoding a prefusion-stabilized, membrane-anchored SARS-CoV-2 full-length spike protein. BNT162b2 is highly efficacious against COVID-19 and is currently authorized for emergency use or conditional approval worldwide. At the time of authorization, data beyond 2 months post-vaccination were unavailable.

Methods In an ongoing, placebo-controlled, observer-blinded, multinational, pivotal efficacy study, 44,165 =16-year-old participants and 2,264 12-15-year-old participants were randomized to receive 2 doses, 21 days apart, of 30 µg BNT162b2 or placebo. Study endpoints reported here are vaccine efficacy (VE) against laboratory-confirmed COVID-19 and safety data, both up to 6 months post-vaccination.

Results BNT162b2 continued to be safe and well tolerated. Few participants had adverse events leading to study withdrawal. VE against COVID-19 was 91% (95% CI 89.0-93.2) through up to 6 months of follow-up, among evaluable participants and irrespective of previous SARS-CoV-2 infection. VE of 86%-100% was seen across countries and in populations with diverse characteristics of age, sex, race/ethnicity, and COVID-19 risk factors in participants without evidence of previous SARS-CoV-2 infection. VE against severe disease was 97% (95% CI 80.3-99.9). In South Africa, where the SARS-CoV-2 variant of concern, B.1.351 (beta), was predominant, 100% (95% CI 53.5, 100.0) VE was observed.

Conclusion With up to 6 months of follow-up and despite a gradually declining trend in vaccine efficacy, BNT162b2 had a favorable safety profile and was highly efficacious in preventing COVID-19. (ClinicalTrials.gov number, NCT04368728)

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During the blinded, controlled period, 15 BNT162b2 and 14 placebo recipients died; during the open-label period, 3 BNT162b2 and 2 original placebo recipients who received BNT162b2 after unblinding died. None of these deaths were considered related to BNT162b2 by investigators. Causes of death were balanced between BNT162b2 and placebo groups (Table S4).

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Confirmed Covid-19 was defined according to the Food and Drug Administration (FDA) criteria as the presence of at least one of the following symptoms: fever, new or increased cough, new or increased shortness of breath, chills, new or increased muscle pain, new loss of taste or smell, sore throat, diarrhea, or vomiting, combined with a respiratory specimen obtained during the symptomatic period or within 4 days before or after it that was positive for SARS-CoV-2 by nucleic acid amplification–based testing, either at the central laboratory or at a local testing facility (using a protocol-defined acceptable test).

Severe Covid-19 is defined by the FDA as confirmed Covid-19 with one of the following additional features: clinical signs at rest that are indicative of severe systemic illness; respiratory failure; evidence of shock; significant acute renal, hepatic, or neurologic dysfunction; admission to an intensive care unit; or death.

Source: Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine

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During the interval from the approximate start of observed protection at 11 days post-dose 1 to before dose 2, VE increased to 91.7% (95% CI 79.6-97.4). From its peak post-dose 2, observed VE declined. From 7 days to <2 months post-dose 2, VE was 96.2% (95% CI 93.3-98.1); from 2 months to <4 months, VE was 90.1% (95% CI 86.6-92.9); and from 4 months to the data cut-off, VE was 83.7% (95% CI 74.7-89.9).

Of 31 cases of severe, FDA-defined COVID-19,12 with onset post-dose 1, 30 occurred in placebo recipients, corresponding to 96.7% VE (95% CI 80.3-99.9) against severe COVID-19 (Fig. 2, Table S6).

Deb and Ed M wrote:

Has anyone heard of a booster geared towards Delta??

Pfizer Press Release July 8, 2021 wrote:

While Pfizer and BioNTech believe a third dose of BNT162b2 has the potential to preserve the highest levels of protective efficacy against all currently known variants including Delta, the companies are remaining vigilant and are developing an updated version of the Pfizer-BioNTech COVID-19 vaccine that targets the full spike protein of the Delta variant. The first batch of the mRNA for the trial has already been manufactured. The Companies anticipate the clinical studies to begin in August, subject to regulatory approvals.

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