The states of COVID-19 today/John Hopkins University of Medicine

New studies are emerging to further define the link between COVID-19 and obesity, and at least one of them offers some hope for the over-weight who catch the disease caused by the SARS-CoV-2 virus.

A purely statistical analysis by an MIT professor who examined infection and mortality data from 99 countries found that the obese are no more likely than anyone else to die from COVID-19.

But there’s a catch.

The study also concluded the obese are far more likely to become infected. Thus the dramatic number of obese people represented among the now more than 1 million fatalities around the globe.

It isn’t that the obese are dying at a greater rate than the non-obese; the problem is that so many more are getting infected that the number of deaths at the same rate make it appear the disease is deadlier for people who are overweight.

“…Obesity has a significant correlation (nearly 40 percent) with the risk of contracting infection from SARS-Cov-2,” writes researcher William Barletta, “although not with the apparent outcome of the infection. The observation of increased risk of infection (although not its outcome) has been previously reported” in a study in The Lancet.

The Lancet study was based on the records of 687 people who sampled positive for COVID-19 among 3,800 in England. The English researchers calculated a 21 percent higher risk for the obese in their sample.

The much larger statistical analysis was conducted by William Barletta, a professor of physics at MIT whose past research has focused on free electron lasers.

He explained that he decided to dive into the global numbers on SARS-CoV-2 “for a less anecdotal and less speculative assessment of risk factors for serious consequences of COVID-19. A data-driven examination of national statistics seems to be in order with the goal of identifying strong correlations of mortality due to COVID-19 with other potential co-morbidities.”

The final study was published at MedRxiv and has not been peer-reviewed. More than 9,300 articles dealing with SARS-CoV-2 have now been published on that preprint servicer since the virus was first identified earlier this year.

There has been considerable debate in the scientific community about all of this non-peer-reviewed work, but some are arguing the debate is irrelevant given that the internet may already have swamped traditional peer review or that crowd-reviewed studies might prove as accurate over time.

The medRxiv (Med Archive) co-founders at Yale University argue that “The Research Revolution Will Not Be Peer Reviewed.”

The numbers

In that vein, Barletta’s number crunching underlines some of the conclusions about COVID-19 reached by other researchers earlier, but also raises questions about others.

He found no significant statistical correlation between asthma or other lung diseases and death from COVID-19 and reported flatly that “in otherwise healthy persons, diabetes does not appear to be a significant risk factor with respect to the seriousness of infection by SARS-Cov-2.”

But in conclusion, Barletta observed that “this statistical study covering countries with approximately 70 percent of the world’s population confirms the early clinical observation that infection by the SARS-Cov-2 virus presents a great risk to persons over the age of 65.

“However, it does not support the suggestions presented by government agencies early in the pandemic that the risks are much greater for persons with certain common potential co-morbidities. Many of the early deaths of elderly patients early in the course of the pandemic took place in circumstances that likely promoted rather than impeded the spread of the virus among person who were generally in a poor state of health.”

Most of the COVID-19 deaths in Sweden came in elder care homes, and Sweden’s Health and Social Affairs Minister Lena Hallengren admitted early in the pandemic that the country “failed to protect our elderly. That’s really serious, and a failure for society as a whole. We have to learn from this, we’re not done with this pandemic yet.”

SARS-CoV-2 didn’t hit Sweden until early March, and people didn’t start dying until a couple weeks later. But by mid- to late-April, 90 to 100 Swedes were dying of the disease by the day and by the start of May, 3,000 were dead.

Sweden took a much more relaxed approach than other countries to try to slow the spread of the disease. Swedes were asked to social distance and large gatherings were banned. But the country avoided lockdowns and mandatory masking.

The policy was widely criticized, but deaths were declining steadily by mid-May, dropped into single digits near the end of July and have remained there since.

They now range between one and three per day in a country where the average, all-cause death rate is near 250 people per day. 

Barletta’s analysis does, however, make clear the effectiveness of lockdowns at slowing the spread of the disease in places where those were instituted, and it confirms the obviously deadly nature of COVID-19.

“The comparison of the severity of medical outcomes of COVID-19 with those caused by influenza strains and their resulting pneumonias displays dramatic differences,” he writes. “Promulgating the idea that COVID-19 a ‘flu-like disease’ spreads gross misinformation to the detriment of the public health worldwide.”

Unfortunately, he adds,  the best methods of dealing with the virus are not yet clear because “authoritative data on a worldwide country-to-country basis are not available to evaluate the effectiveness of prevention and treatment modalities.”

But more is being learned about SARS-CoV-2 on a daily basis, including how it spreads.

Superspreaders

A separate study by scientists from MIT, and the Harvard and Tulane universities suggests age and body mass index (BMI) may play significant roles in how much virus is shed by individuals infected with SARS-CoV-2.

“In our observational cohort study of the exhaled breath particles of 74 healthy human subjects, and in our experimental infection study of eight nonhuman primates infected by aerosol with SARS-CoV-2, we found that exhaled aerosol particles increase one to three orders of magnitude with aging, high BMI, and COVID-19 infection,” they reported.

“These variances appear to be related to changes in airway mucus surface composition and the propensity for mucus surfaces to breakup into small droplets during acts of breathing.”

Their study, they note, suggests there is likely more to the spread of COVID-19 than simply social distance, masks and air currents. Higher rates of shedding might, for instance, help explain the problems with outbreaks in nursing and senior homes, they said.

They also warned that the nature of much discussed droplets might change in those infected with SARS-CoV-2.

“We found that the proportion of small respiratory droplets (the majority of particles exhaled in all subjects) increased at the peak of COVID-19 infection in nonhuman primates,” they wrote. “This diminution in exhaled aerosol particle size indicates that at peak infection there may be an elevated risk of the airborne transmission of SARS-CoV-2 by way of the very small droplets that transmit through conventional masks and traverse distances far exceeding the conventional social distance of two meters.”

Little research has been done in this area, and they called for more.

Their study, they wrote, would appear to indicate a need for more effective masks and more sophisticated social distancing rules, and hints at the possibility that exhaled aerosol numbers could be “not only an indicator of disease progression, but a marker of disease risk in non-infected individuals. Monitoring as a diagnostic might also be an important strategy to consider in the control of transmission and infection of COVID-19 and other respiratory infectious diseases, including influenza.”

They also observed that “approaches to stabilize airway
lining mucus and retain mucus clearance function might be particularly useful” in controlling the spread of the disease by people infected with SARS-CoV-2.