Yes, Covid-19 Aerosols Are Infectious, And More Dangerous than Droplets – Part 1

In 1981, seven American children contracted measles during a visit to the same doctor’s office.

Three of the children had never crossed paths with the 12-year-old source patient. One child arrived at the office an hour after the infected boy had left.

The outbreak caused a stir. At the time, public-health authorities believed measles was transmitted via large respiratory droplets, the kind generated by phlegmy coughs, and required contact within about 1 meter of an infected person.

So ingrained was this belief that a major medical journal, Pediatrics, deemed the outbreak an outlier, concluding that for measles, “airborne spread is unusual.”

Of course, today we know the opposite is true. Microscopic measles particles can remain airborne and infectious for up to 2 hours and can drift far and wide. In one case, an infected athlete transmitted the disease to spectators 100 feet (30.5 meters) away. The notion that measles is primarily contracted through contact with large droplets, rather than via tiny, inhaled aerosols, has been thoroughly debunked.

One year into the Covid-19 pandemic, that same theory has been debunked with respect to SARS-CoV-2 transmission, though infection-control measures have lagged behind the science.

In one regard, the evidence supporting aerosol transmission for Covid-19 is actually stronger than it is for measles: Viable SARS-CoV-2 has been captured via air sampling, a feat that has yet to be achieved with the measles virus.

In fact, only one study, published in 2016, long after experts declared measles airborne, has captured measles RNA in the air — a study its authors called “the first study to directly detect evidence of airborne transmission of measles.” Yet in that study, testing in cell cultures failed to detect viable measles virus.

By contrast, at least six air-sampling studies have isolated SARS-CoV-2 RNA. And one, conducted at the University of Florida, proved SARS-CoV-2 viral particles — captured as far as 4.8 meters from a Covid-19 patient — were viable.

“If this isn’t a smoking gun, then I don’t know what is,” asserts Linsey Marr, PhD, a Virginia Tech aerosol scientist who was not involved in the study.

Marr calls the results “unambiguous evidence that there is infectious virus in aerosols.”

The Florida study, piled atop volumes of other evidence pointing to aerosol transmission, has intensified calls for more robust infection control indoors — in hospitals, nursing homes, dental practices, and retail establishments.

With ultra-contagious SARS-CoV-2 variants now surging globally, the stakes could not be higher.

“It is very clear that aerosols play a considerable role in the transmission of Covid-19 and that we are unlikely to prevail against this pandemic unless we acknowledge that fact,” asserts Justin Morganstern, M.D., a Canadian emergency physician, in an evidence review.

While physical distancing and masks remain important, Morganstern argues, “We should be looking at the extra precautions we can add to stem the spread of this disease.”

Foremost among these precautions should be air filtration and dis-infection, say experts, including Kevin Fennelly, M.D., of the U.S. National Institutes of Health.

At hospitals and nursing homes, infection-control protocols are based on “old data and inferences,” Fennelly asserts in The Lancet Respiratory Medicine. Droplet transmission is not driving the pandemic, he argues, and precautions should be updated to “account for the predominance of small particles within infectious aerosols.”

Coronavirus in the Air

At the pandemic’s outset, health authorities made the same assumption about SARS-CoV-2 that they’d made, erroneously, about measles in the 1980s and tuberculosis in the 1950s: that aerosol transmission, if it happened at all, was “probably very rare.”

But that assumption soon began to wither.

Quickly, it became clear that asymptomatic carriers were spreading Covid-19 in huge numbers, without sneezing or coughing.

What’s more, scientists identified outbreaks — on cruise ships and bus rides, at choir practices and ski resorts, in call centres, restaurants, and shopping malls — that could not be explained by surface or droplet transmission.

Strengthening the case for aerosol spread, scientists captured SARS-CoV-2 genetic material on surfaces that patients could not possibly have touched, such as air outlet vents and air-handling grates.

Even more compelling, coronavirus particles were captured in the air — above flushing toilets, in hospital nurses’ stations and changing rooms, in hallways outside patient rooms, and inside patient rooms beyond 6 feet from the patients.

Still, questions persisted: Was the RNA viable? Could the captured particles actually invade a cell, replicate, and trigger infection? Or were they inert, harmless fragments of genetic material?

The answer was elusive because aerosols, microscopic and fragile, are easily damaged by the air-sampling process.

But the University of Florida team used new, more sophisticated technology, preserving SARS-CoV-2 RNA captured in the air 15 feet from a Covid-19 patient. The genome sequence of the collected virus matched the sequence isolated from the patient.

The study, says lead researcher John Lednicky, PhD, proved “conclusively” that viable SARS-CoV-2 particles, small enough to be inhaled, can linger in the air and pose a risk to those in the vicinity.

The study squelched doubt that Covid-19 can spread — and readily — via aerosols.

Part two coming soon.

Infection Spread in the NICU: “The Tip of the Iceberg” – Part 2

COVID-19 aside, respiratory viral infections (RVIs) strike newborns particularly hard and, according to Austrian researchers, are “more prevalent in the NICU than previously considered.” RVIs are likely underdiagnosed, the authors assert, as many NICUs don’t routinely test for viral pathogens in symptomatic patients. Respiratory viral infections are a leading cause of mortality among newborns and often are detected only late in the course of illness.

Read part one of this blog post here.

Viral Outbreaks in the NICU

Though the majority of NICU infections are bacterial, nosocomial viral infections have been widely reported, including outbreaks of syncytial virus (RSV), influenza H1N1, rotavirus, adenovirus, enterovirus, and norovirus.

COVID-19 aside, respiratory viral infections (RVIs) strike newborns particularly hard and, according to Austrian researchers, are “more prevalent in the NICU than previously considered.”

RVIs are likely underdiagnosed, the authors assert, as many NICUs don’t routinely test for viral pathogens in symptomatic patients. Respiratory viral infections are a leading cause of mortality among newborns and often are detected only late in the course of illness.

The hospital costs of RVIs are particularly high. A 6-year study of a NICU in Nottingham, UK, found that compared to uninfected newborns, infected NICU patients spent far longer in the hospital — 76 days compared to 41 days — and in-hospital care costs were significantly higher, £49,664 compared to £22,155.

Infected NICU staff are often the source of viral outbreaks, especially influenza infection.

Newborns, of course, cannot be vaccinated, and annual vaccination rates among the healthcare workers who care for these patients are alarmingly low.

An H1N1 influenza outbreak in a Greek NICU, for example, was traced to the nursing staff, just 15% of whom were vaccinated.

“Nosocomial influenza can cause considerable morbidity, especially in high-risk neonates,” the authors wrote, “and is readily transmissible in the NICU setting by unvaccinated staff members.”

Viral infection spreads quickly in the NICU. A norovirus outbreak at Texas Children’s Hospital, traced to one newborn, began spreading within 24 hours and within two weeks had afflicted 28 babies, along with 12 staff members, who had to be furloughed.

Disinfecting the NICU Air, Safely and Quietly

Hand hygiene has long been the cornerstone of hospital infection prevention, in the NICU and elsewhere, and healthcare workers are striving to be even more meticulous in the COVID era. Yet hundreds of studies demonstrate that over the decades, compliance has been, in the words of the World Health Organization, “abysmally low.”

Surface cleaning, too, has been augmented since the emergence of SARS-CoV-2 but inevitably falls short, as airborne pathogens continually settle on medical equipment, floors, clothing, and healthcare workers’ hands.

It is impossible to operate [NICU] environments in complete sterility,” a University of California team reported. The infants themselves, the adults who care for them, the equipment required for their care — all represent “fertile vectors for microbial transmission.”

Though stringent cleaning protocols for NICU surfaces have been in place for years, infections rates remain stubbornly high.

“It is tempting to speculate that more potent cleaning techniques or agents will lead to further decreases in nosocomial infections,” the researchers concluded, but reality may be otherwise. “Future improvement may require innovative approaches.”

Among the most effective innovations is ultra-low-energy plasma technology by Novaerus, now deployed in NICUs and COVID wards worldwide. Easily installed on the wall, a shelf, or a rolling stand, Novaerus devices quickly destroy airborne viral, bacterial, and fungal particles.

For example, lab tests found the company’s most powerful unit can reduce the airborne load of MS2 Bacteriophage, a virus used as a surrogate for SARS-CoV-2, by 99.99% in just 15 minutes. The technology decimates MRSA load just as thoroughly and quickly.

Dis-infecting air in the NICU, as well as other wards and common areas, is imperative, as study after study points to hospital infection spread via aerosolization. A Japanese team, for example, reported on an outbreak of Bacillus cereus in its NICU, concluding the bacteria spread via the airflow of the ventilation system. Numerous studies have detected MRSA and Clostridicum difficile in hospital air.

As for SARS-CoV-2, air-sampling studies have detected viral RNA in hospital hallways and in rooms where healthcare workers changed their clothing, prompting the World Health Organization to finally agree with scientists worldwide that aerosol transmission of COVID-19 cannot be ruled out.

In a year-long study of an American NICU, a team of environmental engineers noted in PLOS One: “Hospital hygiene protocols may undervalue the potential importance of the airborne transmission route.”

Throughout hospitals, but especially in the NICU, ultra-low-energy plasma technology is an important addition to ventilation and filtration. Whereas conventional filters capture only large particles, Novaerus units destroy the smaller and deadlier ones.

Novaerus units run continuously and quietly, a benefit given the adverse effect of noise on the heart rates and respiratory systems of preterm or very low birth weight infants.

The technology is safe to operate around even the smallest, most medically fragile NICU patients, unlike other air-sanitation methods that can produce harmful byproducts.

Novaerus technology not only helps prevent infection but also mitigates newborns’ exposure to chemicals such as volatile organic compounds (VOCs) and particulate matter. Lacking the protective buffer of the womb, research suggests, newborns in the NICU are exposed to chemicals that may permanently alter neurobehavioral outcomes.

Air quality in the NICU may have a “significant impact on their long-term development,” note researchers at the Icahn School of Medicine at Mount Sinai in New York City, who are conducting the first study of air quality in neonatal intensive care.

Infants admitted to the NICU often stay for long periods, putting them at elevated risk for contracting an infection. The average length of stay for a term or near-term infant with surgical or respiratory issues is about 15 days; the length of stay for preterm infants born at 26 weeks’ gestation is more than 2 months.

Throughout their stay, it is imperative that their infection risk is reduced by stringent hand hygiene, effective surface cleaning, and 24/7 air dis-infection.

Microbes accumulate 24 hours a day, as visitors, staff, and medical devices come and go. Healthcare workers’ hands and NICU equipment cannot be cleaned continually, but with the installation of Novaerus technology, the air in the NICU can.