Coronavirus: Just breathing or talking might be enough to spread infection, cautions NAS expert
An infected person may be able to spread the new coronavirus simply by breathing or talking, an expert from the National Academy of Sciences (NAS) has warned. While current research is limited, “the results of available studies are consistent with aerosolization of virus from normal breathing,” says Harvey Fineberg, who chairs the standing committee on Emerging Infectious Diseases and 21st Century Health Threats at NAS, in a letter to the White House.
The April 1 letter is addressed to Kelvin Droegemeier, who is the head of the White House Office of Science and Technology Policy. The letter is in response to Droegemeier’s question on whether concerning the possibility that the new coronavirus which causes COVID-19 could spread by conversation, in addition, to sneeze or cough-induced droplets.
“Individuals may vary in the degree to which they produce bioaerosols through normal breathing. This may have a bearing on the efficiency of transmission of SARS-COV-2 by different infected but asymptomatic individuals,” says the letter.
The response in the letter is based on a review of available studies. The letter, for example, cites a recent analysis by the University of Nebraska Medical Center (UNMC), which found widespread contamination of the environment near patients with COVID-19.
The UNMC study found that many commonly used items, toilet facilities, and air samples had evidence of the genetic material from the virus, indicating that “SARS-CoV-2 material is widely disseminated” in the environment. “These findings indicate that disease might be spread through both direct (droplet and person-to-person) as well as indirect contact (contaminated objects and airborne transmission) and suggests airborne isolation precautions could be appropriate. Additional research in this important area is underway,” said the study.
The expert says in the letter that further research specific to the aerosolization of the novel coronavirus during breathing and speech, shows the behavior of the virus-containing aerosols in the environment -- both from laboratory studies and clinical experience -- as well as the infectivity of bioaerosols containing the virus, could provide a more complete understanding of the level of risk of transmission of the virus “via bioaerosols spread by exhalation and normal speech.”
The World Health Organization (WHO) says that according to current evidence, the COVID-19 virus is primarily transmitted between people through respiratory droplets and contact routes. Droplet transmission occurs when a person is in close contact (within 1 meter) with someone who has respiratory symptoms (for example, coughing or sneezing) and is therefore at risk of having his/her mouth, nose or eyes exposed to potentially infective respiratory droplets.
Transmission may also occur through fomites in the immediate environment around the infected person.
“Therefore, the transmission of the COVID-19 virus can occur by direct contact with infected people and indirect contact with surfaces in the immediate environment or with objects used on the infected person (for example, stethoscope or thermometer),” says the WHO.
According to Fineberg’s letter, the new coronavirus may spread through the air in tiny particles that infected people exhale during normal breathing and speech. Large droplets are still a means of infection, but researchers say that tiny airborne particles may also carry the infectious virus.
“Currently available research supports the possibility that SARS-CoV-2 could be spread via bioaerosols generated directly by patients’ exhalation,” says the letter. “One must be cautious in imputing the findings with one respiratory virus to another respiratory virus, as each virus may have its own effective infectious inoculum and distinct aerosolization characteristics,” it says.
According to the WHO scientific brief, which was updated on March 29, it says that in the context of COVID-19, airborne transmission may be possible in specific circumstances and settings in which procedures or support treatments that generate aerosols are performed.
This includes “endotracheal intubation, bronchoscopy, open suctioning, administration of nebulized treatment, manual ventilation before intubation, turning the patient to the prone position, disconnecting the patient from the ventilator, non-invasive positive-pressure ventilation, tracheostomy, and cardiopulmonary resuscitation,” says WHO.
The NAS letter, however, does not address whether wearing a mask could protect the person from getting infected.
Meanwhile, after the US Centers for Disease Control and Prevention (CDC) Director, Dr Robert Redfield, said recently that the agency is reviewing the use of masks as up to 25% of people infected with coronavirus may not show symptoms, there are reports that the CDC may advise all Americans to wear cloth masks in public.
“In a draft document obtained by STAT, the CDC recommended that the public use homemade face coverings when in public, reserving higher-grade protective equipment like N95 masks for hospitals and healthcare workers, who have faced severe shortages in personal protective equipment as the coronavirus pandemic has accelerated through the US,” says a report published by STAT.
At a White House briefing on Thursday evening, US President Donald Trump said that the CDC was “coming out with regulations” on mask-wearing but stressed that the guidance would be voluntary.