The Observatory and Fast Facts

Jan. 21, 2021
COVID-19 model compares effectiveness of vaccine and mitigation strategies

Predicting the spread of COVID-19 using standard statistical models has its challenges, which is why two Iowa State University researchers developed a network-based approach to look at the impact of specific policies and vaccination strategies throughout the many stages of the pandemic, according to a press release from the university.

In a paper, published on medRxiv prior to peer review, the researchers used their social-interaction network model to understand how homophily – the tendency to associate with people who share the same opinions and beliefs, in this case about COVID-19 – affects the probability of an outbreak and the number of deaths. The model compares the probability of an outbreak for different levels of homophily and correlations among beliefs about vaccination and social distancing. The researchers kept the same proportion of individuals with positive beliefs in all scenarios to provide an apples-to-apples comparison.

The model showed that the presence of homophily can have a strong influence on the probability of an outbreak. Homophily regarding vaccination implies there are clusters of vaccinated people but also clusters of unvaccinated people. The researchers found that such homophily in social interaction networks can lead to substantially more frequent outbreaks, especially in the presence of an effective vaccine.

They also found outbreaks occurred more frequently when there was a positive correlation between beliefs about vaccination and social distancing. If individuals who get the vaccine are the same people who are more likely to social distance, there is a percentage of the population not taking any protective measures, increasing the risk of an outbreak.

When there is a negative correlation – people get the vaccine, but don’t social distance or people social distance, but don’t get the vaccine – there are fewer outbreaks, because more people are following one of the mitigation strategies. The researchers said their model provides a more realistic assessment of how our interactions and increasing polarization of opinion impact the spread of the virus.

Study uncovers blood vessel damage and inflammation in COVID-19 patients’ brains

In an in-depth study of how COVID-19 affects a patient’s brain, researchers at the National Institutes of Health (NIH) consistently spotted hallmarks of damage caused by thinning and leaky brain blood vessels in tissue samples from patients who died shortly after contracting the disease, according to a press release from NIH.

In addition, they saw no signs of SARS-CoV-2 in the tissue samples, suggesting the damage was not caused by a direct viral attack on the brain. The results were published as a correspondence in the New England Journal of Medicine.

Although COVID-19 is primarily a respiratory disease, patients often experience neurological problems including headaches, delirium, cognitive dysfunction, dizziness, fatigue, and loss of the sense of smell. The disease may also cause patients to suffer strokes and other neuropathologies.

In this study, the researchers conducted an in-depth examination of brain tissue samples from 19 patients who had died after experiencing COVID-19 between March and July 2020. Samples from 16 of the patients were provided by the Office of the Chief Medical Examiner in New York City while the other 3 cases were provided by the department of pathology at the University of Iowa College of Medicine, Iowa City. The patients died at a wide range of ages, from 5 to 73 years old. They died within a few hours to two months after reporting symptoms. Many patients had one or more risk factors, including diabetes, obesity, and cardiovascular disease. Eight of the patients were found dead at home or in public settings. Another three patients collapsed and died suddenly.

Initially, the researchers used a special, high-powered magnetic resonance imaging (MRI) scanner that is 4 to 10 times more sensitive than most MRI scanners, to examine samples of the olfactory bulbs and brainstems from each patient. These regions are thought to be highly susceptible to COVID-19. Olfactory bulbs control our sense of smell while the brainstem controls our breathing and heart rate. The scans revealed that both regions had an abundance of bright spots, called hyperintensities, that often indicate inflammation, and dark spots, called hypointensities, that represent bleeding.

The researchers then used the scans as a guide to examine the spots more closely under a microscope. They found that the bright spots contained blood vessels that were thinner than normal and sometimes leaking blood proteins, like fibrinogen, into the brain. This appeared to trigger an immune reaction. The spots were surrounded by T cells from the blood and the brain’s own immune cells called microglia. In contrast, the dark spots contained both clotted and leaky blood vessels but no immune response.

Questionnaire identifies COVID-19 impact and challenges among healthcare organizations

Healthcare organizations across all settings have faced common challenges during COVID-19, including staffing issues, obtaining supplies, and implementing safety protocols and guidelines, according to a survey conducted by The Joint Commission and reported in a press release.

To learn about the needs of organizations in the current and evolving pandemic environment, The Joint Commission conducted an online questionnaire in September 2020 among healthcare organizations that work with The Joint Commission, Joint Commission Resources, and the Joint Commission Center for Transforming Healthcare.

The questionnaire, administered by C+R Research, had a total of 735 respondents representing a variety of healthcare settings, including hospitals, home care, behavioral health and human services, and ambulatory care.

Most survey participants reported a medium to high impact on their organizations from COVID-19 and often perceived a higher impact than the number of COVID-19 cases in their area may have indicated.

Survey participants said the most common changes resulting from COVID-19 included increased communication to keep staff updated on changes and to support their well-being, increased working-from-home activities and changed plans to deal with staffing shortages. They also said they established and updated protocols, such as for infection prevention and emergency management plans.

When asked about valuable resources, participants pointed to those that helped them monitor changes and adapt their plans accordingly. These included communications on regulatory or guideline changes resulting from COVID-19, information on modifications to infection prevention plans and additional training as governmental recommendations evolved.

Los Alamos study hopes to characterize and optimize ventilator treatment for COVID-19

Cross-disciplinary scientists and engineers at Los Alamos National Laboratory are working to learn how Intrapulmonary Percussive Ventilation (IPV) helps clear mucus from blocking the airways of the human lung, a common reaction to the COVID-19 virus, according to a press release.

Researchers, using some of the same modeling and experimental techniques from the laboratory’s nuclear weapons mission, are working to discover the underlying science and engineering principles behind this process and have developed a preliminary machine learning algorithm that could someday assist pulmonary doctors in treating COVID-19 patients with IPV.

IPV is used alongside traditional ventilation to deliver rapid pulses of aerosol, depositing medication and potentially opening up clogged airway passages in the lung. Researchers are merging numerical and experimental approaches to develop a predictive model of lung behavior under these conditions.

The lung is a highly complex system, so the laboratory is using acoustic measurements, computational fluid dynamics models, structural-fluid interaction models, and optical techniques to model the breathing process and observe aerosol flow and mucus breakup. This is especially challenging because of the complex geometries in lung structure, multifaceted boundary conditions in the deep lung, and non-linear behavior of viscus fluids in the lung. The study requires analysis of how the lung responds to the kinetic energy of variable pressures, rotational flows, and sheer stresses on the lung walls.

To inform the mathematical models, the research team designed, built and tested several experimental devices, including a 3D printed “gas distribution manifold” that mimics the structures of the lung’s trachea and bronchial branches. They used sensors to measure pressure, velocity, temperature and humidity, along with a gas analyzer to measure pressure and volume, optical sensors to detect aerosol density and spectrometers to look at particle size distribution. They also used lung tissue harvested from sheep carcasses and dyed aerosol to track the deposition of IPV aerosols during a ventilation-assisted process.

The preliminary machine learning algorithm ties all the variables together, with the hope of eventually creating a rapid, patient-specific tool for estimating the proper ventilator and IPV settings for a particular patient before ventilation is begun, responding to and optimizing the treatment for each patient. 

CDC reports on allergic reactions to COVID-19 vaccine 

During December 14-23, 21 cases of anaphylaxis, a life-threatening allergic reaction, were reported after administration of the first dose of the Pfizer-BioNTech COVID-19 vaccine, or a rate of 11.1 cases per million doses, compared with 1.3 cases per million doses for the flu vaccine, officials from the Centers for Disease Control and Prevention (CDC) reported at a press conference.

The agency also reported on the findings in its Morbidity and Mortality Weekly Report (MMWR).

“The anaphylaxis rate for COVID-19 may seem high compared to flu vaccines, but I want to reassure you this is still a rare outcome,” said Nancy Messonnier, MD, Director of CDC’s National Center for Immunization and Respiratory Diseases. “That doesn’t mean we couldn’t see potential serious health events in the future,” she added, saying that the CDC and FDA are reviewing all serious adverse event reports.

“I also think it is important to remember that many adverse events following immunization are coincidental,” Messonnier said.

The findings were based on the first doses of the vaccine distributed in the United States following the decision by the U.S. Food and Drug Administration (FDA) to issue an emergency use authorization (EUA) for the Pfizer-BioNTech COVID-19 vaccine on December 11, 2020.

The vaccine is administered in two doses separated by 21 days.

As of December 23, 2020, a total of 1,893,360 first doses of the Pfizer-BioNTech COVID-19 vaccine had been administered in the United States, and reports of 4,393 (0.2 percent) adverse events after receipt of the Pfizer BioNTech COVID-19 vaccine had been submitted to the CDC. Among these, 175 case reports were identified for further review as possible cases of severe allergic reaction.

Based on the data, the CDC said providers should follow the agency’s guidelines for COVID-19 vaccine administration for vaccines from both Pfizer-BioNTech and Moderna, which received EUA approval from the FDA for its vaccine on December 18., 2020.

“Locations administering COVID-19 vaccines should adhere to CDC guidance for use of COVID-19 vaccines, including screening recipients for contraindications and precautions, having the necessary supplies available to manage anaphylaxis, implementing the recommended post-vaccination observation periods, and immediately treating suspected cases of anaphylaxis with intramuscular injection of epinephrine,” the CDC wrote in the MMWR.

CDC also said that people who had an immediate reaction to the first dose should not get a second dose. Similarly, people who are allergic to any of the components in the vaccines also should not be vaccinated.

CDC officials also said they plan to publish a similar MMWR report on adverse events associated with the Moderna vaccine.