Vaccinated Individuals Infected With Delta Variant May Carry as Much Virus as Unvaccinated

The U.S. Centers for Disease Control and Prevention (CDC) updated their mask guidance on July 27, 2021, recommending that individuals wear masks indoors in areas with substantial or high transmission rates. This change was prompted largely by a recent study of an outbreak of SARS-CoV-2 infections in which 74% of those infected were fully vaccinated. This outbreak was linked to the highly transmittable Delta variant. Tests on samples taken from vaccinated and unvaccinated individuals infected with SARS-CoV-2 showed similar levels of virus in the body, which if confirmed through more rigorous studies, would strongly suggest that vaccinated individuals can transmit and infect others with SARS-CoV-2 as well as unvaccinated individuals. It is important to note that while there was a high percentage of breakthrough infections among the vaccinated, only 1.2% were hospitalized and none died — further demonstrating that the vaccines offer protection against severe COVID.

70% of Americans Vaccinated

On Monday, August 2, 2021, the Biden administration announced that 70% of the population has been vaccinated with at least one dose, a month late from their original target of July Fourth weekend. In recent weeks, vaccination rates have climbed as the highly contagious Delta variant has led to a spike in hospitalizations and cases. A handful of big companies released their vaccination plans to require workers who plan to come into the office to provide proof of being fully vaccinated. In addition, starting in mid-August 2021, New York City will mandate patrons of performances, gyms and restaurants to carry proof of one vaccine to gain entry.

Full FDA Approval of COVID Vaccine Possible by September 2021

One of the mRNA-based COVID-19 vaccine producers for months has asked for full approval from the Food and Drug Administration (FDA) for their vaccine that has been in circulation under an emergency use authorization (EUA) since December 2020. Many believe, and are supported by the results of a Kaiser Family Foundation poll, that a full approval of the vaccine may drive those skeptical of the vaccine to get it. Though typically a full vaccine approval takes months to complete, it was recently reported that FDA may grant full approval as early as September 2021.

CDC to Track Infections of Vaccinated Individuals

In May 2021, the CDC stopped tracking COVID-19 cases in vaccinated individuals that did not lead to hospitalization or death. Recently, the agency has gotten pressure to reverse this decision and to encourage states to collect data on all breakthrough cases — when a vaccinated individual tests positive for COVID-19 — regardless of outcome. Experts note better reporting can assist in curbing outbreaks as recent data has shown vaccinated individuals are able to spread disease as easily as those who aren’t. To further complicate matters, most vaccinated individuals, even when exposed to COVID-19, are less likely to get tested, leading to more missing holes in the data.

Predicting Vaccine Efficacy Requires Correlates

A critical area of focus for researchers has been identifying and establishing “correlates of protection” related to the use of vaccines. Correlates of protection bring a number of benefits, including streamlined development of safe and effective COVID vaccines through, for example, evaluating immune response rather than conducting full phase 3 efficacy clinical studies. This could allow for availability of more vaccines at a time when establishing large comparative clinical trials is difficult due to high levels of vaccinated populations or difficulty in recruiting participants.

Correlates of protection, which are specific to particular endpoints (for example, protection from severe disease or death), are already used for development of other vaccines such as for the flu. A recent nonclinical study has found that certain neutralizing antibodies elicited from one type of authorized mRNA vaccine serve as immune correlates of protection, at least in nonhuman primate models, indicating significant reduction in virus replication in both the nasal areas (upper airways) and deep lung (lower airways). The study is important as researchers specifically would like to identify and understand the behavior of immune correlates of protection in both areas of the airways, and the study showed differences between the two areas in antibody elicitation and effects based on vaccine dosing. Such findings could impact vaccination strategies, e.g., dosing to reduce transmission versus dosing to reduce severe disease in the lung.

Inflammation Impacts the Brain of COVID-19 Patients

The latest evidence — reported here and here — supports earlier findings reported here and here about molecular, cellular and tissue changes in the brain that may account for neurological disturbances in COVID-19 patients. The most likely mechanism that emerges from these studies is that inflammatory signals, which the body develops in response to the SARS-CoV-2 infection, cross the blood-brain barrier and lead to altered gene expression and other biochemical changes in the brain. The observed pathology was similar to that seen in patients suffering from neurodegenerative diseases. Hypoxia (low blood oxygen levels) and “micro-hemorrhages” — which also are hallmarks of COVID-19 and affect the entire body — further impair brain functioning.

Attitudes of the Unvaccinated Vary

The results of a poll conducted in mid-July 2021 in the United States indicate that among adults who remain unvaccinated, the attitudes towards vaccination vary from “wait and see” to “will vaccinate only if required” to “definitely not getting vaccinated.” The proportion of this last category has remained steady, comprising 15% of respondents in December 2020 and 14% in July 2021. The survey also found that the unvaccinated individuals are less worried about COVID-19 and are less likely to wear a mask, compared to the vaccinated population.

CT Imaging Helps Diagnose COVID-19

A review of published studies examined the usefulness of computer tomography (CT) imaging in suspected COVID-19 cases. The CT scans are particularly helpful when the clinical picture is complicated by concurrent medical conditions. The presented summary has a wealth of information both for physicians and researchers working to combat COVID-19. Another potential method for rapidly diagnosing COVID-19 is based on applying artificial intelligence (AI) tools to electrocardiogram (ECG) results.

Exercise-Related Particle Generation

Researchers counted and measured particles in the air that were produced by intense breathing during class exercises. They found that particles with diameters of 0.3 to 10 microns, which typically linger in the air and are easily breathed in, were generated during classes of just four or five individuals, despite their wearing a disposable “procedural” mask (which is less protective than a surgical mask). The particle count reached a maximum about half an hour into the exercise routine. This observation should help assess risk in cases where the infectiousness status of an exercise class participant is unknown.