Since the beginning of the pandemic, the most frightening task in the health field was thought to be when a doctor placed a breathing tube in the trachea of a patient in Covid’s critical condition.
Those who perform these “aerosol-generating” procedures, usually in an intensive care unit, receive the best protective equipment, even if there is not enough for everyone, according to the guidelines of the Center for Disease Control and Prevention. And for anyone working with Covid patients, up to a month ago, a surgical mask was considered sufficient.
A new wave of research now shows that several 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 speaking or breathing, even in a well-ventilated room, can make employees sick with the CDC-sanctioned surgical masks. Studies suggest that the highest overall risk of infection was among frontline workers – many of them black – who spent most of their time with patients at the onset of their illness and with below average protective equipment, not those who worked at the Covid ICU.
“The whole thing is upside down as it currently stands,” said Dr. Michael Klompas, an associate professor at Harvard Medical School who called the phrase “aerosol-generating procedure” an “improper name” in a recent article in Journal of the American Medical Association.
“It is a big mistake,” he said.
The growing body of studies showing the spread of Covid-19 aerosol during choir practice, on a bus, in a restaurant and in gyms has drawn public attention and led to a widespread interest in better masks and ventilation.
However, the issue has been highly controversial in the healthcare sector. For more than a year, union leaders from international and United States nurses have asked healthcare professionals who care for possible or confirmed Covid patients to have the highest level of protection, including N95 masks.
But many experts, supported by national hospital associations and California, have long insisted that N95s be reserved for those who perform aerosol-generating procedures, saying that other frontline staff can safely care for Covid patients by wearing less surgical masks. protective.
The guidelines further say that a worker would not be considered “exposed” to Covid-19 after caring for a sick Covid patient while wearing a surgical mask. Still, in recent months, Klompas and researchers in Israel have documented cases in which 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 when caring for patients or residents with suspected or confirmed” Covid “, but unfortunately, respirators are not always available to healthcare personnel due to the lack of supplies ”.
Another new survey by scientists at Harvard and Tulane found that so-called Covid super-spreaders – the 20% of people who emit 80% of the tiny particles – tend to be obese or older, a population more likely to live in the care of the elderly or be hospitalized.
When highly infectious, these patients emit three times more tiny aerosol particles (about a billion a day) than younger or non-obese people. An infected super-spreader who is simply breathing can pose as much or more risk to healthcare professionals than a coughing patient, said David Edwards, an associate professor of bioengineering at Harvard and author of the study.
The study sheds light on the serious risks faced by nursing home workers, of whom more than 546,000 contracted Covid and 1,590 died, according to reports from nursing homes submitted to the Centers for Medicare and Medicaid since mid-May.
Taken together, the research suggests that exposure in the health 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 studies, but was not involved in any of them.
“The result is that it is the inhalation” of tiny airborne particles that leads to infection, said Milton, a professor at the University of Maryland School of Public Health who studies how respiratory viruses spread, “which means wearing loose surgical masks. not enough . “
On February 10, the CDC updated its guidelines for healthcare professionals, excluding the suggestion that wearing a surgical mask when caring for Covid patients was acceptable and urging workers to wear an N95 or a “tight fitting face mask”, which it could include a comfortable cloth mask over a looser surgical mask.
However, the update came after nearly 3,500 U.S. health workers have died from Covid, as documented by the Guardian / KHN in the Lost on the Frontline project.
The project is more comprehensive than any record by the United States government of deaths of health workers. Current CDC data shows 1,391 health worker deaths, 200 less than the total number of employee deaths in Covid nursing homes reported to the US Medicare and Medicaid Centers.
More than half of the deceased workers with known occupation were nurses or in health support functions. These teams generally have the most extensive contact with the patient, taking care of their IVs and transforming them into hospital beds; brushing their hair and giving them a sponge bath in nursing homes. Many of them – two out of three – were black workers.
Two anesthetists in the UK – doctors who perform ICU intubations – saw data showing that non-ICU workers were dying at exaggerated rates and began to question the notion that “aerosol-generating” procedures were the most risky.
Dr. Tim Cook, an anesthesiologist at Royal United Hospitals Bath, said the guidelines that highlight these procedures were based on research from the first SARS outbreak in 2003. A widely cited 2012 study warned that these previous studies were of “very low quality” “and said there was a” significant research gap “that needed to be filled.
But the research was never carried out before the emergence of Covid-19, Cook said, and important differences emerged between Sars and Covid-19. In the first SARS outbreak, patients were most contagious by the time they arrived at the hospital in need of intubation. Even so, studies with Covid patients in early summer began to show that the peak of contagion occurred days earlier.
Cook and colleagues found in October that the feared practice of intubation emitted about 20 times less aerosols than a cough, said Dr. Jules Brown, a UK anesthetist and another 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 in Scotland and Australia validated these findings in a pre-published article on February 10, showing that two other aerosol-generating procedures were not as dangerous as speaking, breathing heavily or coughing.
Brown said the initial shortage of PPE led to rationing and targeted better respiratory protection for anesthetists and intensivists like him. Now that it is known that emergency room workers and nursing homes are also at extreme risk, he said, he cannot understand why the old guidelines remain largely the case.
“It was all a big house of cards,” he said. “The base was unstable and, in my head, everything collapsed.”
Asked about the research, a CDC spokesman said by email: “We are excited about the publication of new studies with the aim of solving this problem and better identifying which procedures in healthcare environments can be aerosol generators. As studies accumulate and findings are replicated, the CDC will update its list of what procedures are considered [aerosol-generating procedures]. “
Cook also found that doctors who perform intubations and work in the ICU were at lower risk than those who worked on general medical floors and found patients in the early stages of the disease.
In Israel, doctors at a children’s hospital documented the viral spread of the mother of a three-year-old patient to six members of the team, although all were masked and detached. The mother was pre-symptomatic and the authors said in the January 27 study that the case was a possible “evidence of airborne transmission”.
Harvard’s Klompas made a similar discovery after leading an in-depth investigation into a September outbreak among patients and staff at Brigham and Women’s Hospital in Boston.
There, a patient with a negative test for Covid, two consecutive days ended up developing the virus and infecting several employees and patients. Among them were two patient care technicians who treated the patient using surgical masks and face shields. Klompas and his team used genome sequencing to connect sick workers and patients to the same outbreak.
The CDC guidelines do not consider the care of a Covid patient with a surgical mask as a source of “exposure”, therefore, had it not been an in-depth study, the cases of technicians and others could have been dismissed as unrelated to work.
The guidelines’ large focus on the risks of “aerosol-generating” procedures made hospital administrators assume that those in the ICU fell ill at work and those who worked elsewhere were exposed in the community, said Tyler Kissinger, an organizer of the National Health Workers Union in Northern California.
“What happens is this disparity in which exposures are taken seriously,” he said. “A phlebotomist, environmental services worker or nursing assistant who had contact with the patient – just wearing a surgical mask and not an N95 – was not being treated as having been exposed. They had to keep working ”.
-
KHN (Kaiser Health News) is a national newsroom that produces in-depth journalism on health issues. Along with Policy Analysis and Polling, KHN is one of the three main operational programs of the KFF (Kaiser Family Foundation). KFF is a non-profit organization that provides information on health issues for the country