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Since the start of the pandemic, the most terrifying task in healthcare was thought to be putting a breathing tube in the trachea of a critically ill Covid patient.
Those who perform such “aerosol-generating” procedures, often in an intensive care unit, have the best protective equipment even if there isn’t enough for everyone, according to the Centers for Disease Control guidelines. and Prevention. And for anyone working with Covid patients, until a month ago, a surgical mask was considered sufficient.
A new wave of research now shows that many of these procedures were not the most dangerous. Recent studies have determined that a basic cough produces about 20 times more particles than intubation.
Other new studies show that patients with Covid, simply by speaking or breathing, even in a well-ventilated room, could make workers sick in CDC-sanctioned surgical masks. Studies suggest the highest overall risk of infection was among frontline workers – many of whom were workers of color – who spent the most time with patients earlier in their illness and in inferior protective clothing. to normal, and not those who worked in the Covid intensive care unit.
“The whole thing is backwards as it is currently worded,” said Dr. Michael Klompas, associate professor at Harvard Medical School who called the term “aerosol-generating procedure” a “misnomer. In a recent article in the Journal of the American Medical Association.
“It’s a huge mistake,” he said.
The growing number of studies showing the aerosol spread of Covid-19 during choir practice, on a bus, in a restaurant and in gyms has attracted public attention and has led to widespread interest in better masks and better ventilation.
Yet the subject has been very controversial in the healthcare industry. For more than a year, international and US nurses union leaders have called on health workers caring for potential or confirmed Covid patients to be provided with the highest level of protection, including N95 masks.
But many experts, backed by national and California hospital associations, have long insisted that N95s be reserved for those performing aerosol-generating procedures, saying other frontline workers can safely care for Covid patients. while wearing less protective surgical masks.
The guidelines still state that a worker would not be considered “exposed” to Covid-19 after treating a sick Covid patient while wearing a surgical mask. Yet in recent months, Klompas and researchers in Israel have documented cases where workers wearing surgical masks and face shields have fallen ill with Covid after providing routine patient care.
The CDC said in an email that N95 respirators have remained preferred over face masks for treating patients or residents with “suspected or confirmed Covid”, but unfortunately respirators have not always been available to staff of health due to supply shortages ”.
Other new research by scientists at Harvard and Tulane has found that so-called Covid super-spreaders – the 20% of people who emit 80% of tiny particles – tend to be obese or older, a population more likely to live in elderly care or be hospitalized.
When highly infectious, these patients emit three times as many tiny aerosol particles (about one billion per day) than younger or non-obese people. An infected super-spreader who is simply breathing can pose as much or more of a risk to health workers than a patient with a cough, said David Edwards, Harvard faculty associate in bioengineering and study author.
The study clarifies the serious risks facing nursing home workers, of whom more than 546,000 have contracted Covid and 1,590 have died, according to nursing home reports filed with the Centers for Medicare and Medicaid since the mid-May.
Taken together, the research suggests that exposure in the health care workplace was “much greater” than what the CDC defined by prioritizing the protection of those who perform “aerosol-generating” procedures. said Dr Donald Milton, who reviewed the studies but was not involved in any of them. .
“The result is that it is inhaling” tiny airborne particles that lead to infection, said Milton, a professor in the University of Maryland’s faculty of public health who studies the spread of viruses. respiratory, “which means that loose surgical masks are not sufficient.”
On February 10, the CDC updated its guidelines for healthcare workers, removing the suggestion that wearing a surgical mask while caring for Covid patients was acceptable and urging workers to wear an N95 or “face mask”. well-fitting facial ”, which could include a fabric mask over a looser surgical mask.
Still, the update came after nearly 3,500 U.S. healthcare workers have already died from Covid, as the Guardian / KHN documented in Project Lost on the Frontline.
The project is more comprehensive than any US government tally of health worker deaths. Current CDC data shows 1,391 healthcare worker deaths, 200 fewer than the total staff of Covid deaths that nursing homes have reported to the US Centers for Medicare and Medicaid.
More than half of the deceased workers whose occupation was known were nurses or health support positions. These staff members often have the most extensive contact with patients, tending to their IVs and turning them into hospital beds; brush hair and bathe it with a sponge in nursing homes. Many of them – two out of three – were workers of color.
Two anesthesiologists in the UK – doctors who perform ICU intubations – saw data showing that non-ICU workers were dying at disproportionate rates and began to question the idea that procedures “generate aerosols” were the riskiest.
Dr Tim Cook, an anesthesiologist at Royal United Hospitals Bath, said the guidelines identifying these procedures were based on research conducted during the first Sars outbreak in 2003. A widely cited study from 2012 warned that these earlier studies were of “very low” quality and said there was a “significant research gap” that needed to be filled.
But research never took place before the onset of Covid-19, Cook said, and key differences emerged between Sars and Covid-19. In the first Sars outbreak, patients were most contagious by the time they arrived at a hospital requiring intubation. Yet studies of Covid patients in early summer began to show that the peak in contagion occurred days earlier.
Cook and his colleagues discovered in October that the dreaded practice of intubation emits about 20 times less aerosol than a cough, said Dr Jules Brown, a British anesthesiologist and other study author. Extubation, also considered an “aerosol-generating” procedure, generated a little more aerosol, but only because patients sometimes cough when the tube is removed.
Since then, researchers from Scotland and Australia have validated these results in an earlier article published on February 10, showing that two other aerosol-generating procedures were not as dangerous as talking, breathing excessively or coughing.
Brown said initial PPE supply shortages led to rationing and directed the best respiratory protection to anesthesiologists and intensivists like him. Now that it is known that emergency room and nursing home workers are also at extreme risk, he said, he cannot understand why the old guidelines are largely maintained.
“It was a big house of cards,” he said. “The foundation was fragile and in my mind it all fell apart.”
Asked about the research, a CDC spokesperson said via email: “We are encouraged by the publication of new studies aimed at addressing this issue and better identifying procedures in healthcare facilities that can generate aerosols. As studies accumulate and results are replicated, the CDC will update its list of considered procedures. [aerosol-generating procedures]. “
Cook also found that doctors who perform intubations and work in the intensive care unit were less at risk than those who worked in general medical floors and saw patients in early stages of the disease.
In Israel, doctors at a children’s hospital have documented a viral spread from the mother of a three-year-old patient to six staff, although everyone has been masked and left behind. The mother was pre-symptomatic and the authors said in the Jan. 27 study the case was “evidence of airborne transmission.”
Klompas, of Harvard, made a similar conclusion after conducting an extensive investigation into a September outbreak among patients and staff at Brigham and Women’s Hospital in Boston.
There a patient who tested negative for Covid, two days in a row ended up developing the virus and infecting many staff and patients. Among them were two patient care technicians who treated the patient while wearing surgical masks and face shields. Klompas and his team used genome sequencing to connect sick workers and patients to the same outbreak.
CDC guidelines do not consider treating a Covid patient in a surgical mask as a source of “exposure”, so without the in-depth study, the cases of technicians and others could have been dismissed as unrelated to the job.
The strong focus of guidance on the dangers of “aerosol-generating” procedures meant that hospital administrators assumed those in the ICU fell ill on the job and those working elsewhere were exposed in the community, said Tyler Kissinger, a national union organizer. health care workers in northern California.
“What is at play there is this disparity in the exhibitions whose exhibitions are taken seriously,” he said. “A phlebotomist or environmental service worker or nursing assistant who had been in contact with a patient – wearing just a surgical mask and not an N95 – was not treated as having been exposed. They had to keep coming to work.
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KHN (Kaiser Health News) is a national newsroom that produces in-depth journalism on health issues. Along with policy analysis and surveys, KHN is one of the three main operational programs of the KFF (Kaiser Family Foundation). KFF is a nonprofit organization with information on health issues in the nation
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