The risk of getting COVID-19 from a symptom-free person, they said, was very low. Officials downplayed the need for large-scale protective equipment for all healthcare workers and rejected the use of masks for the general public as potentially dangerous.
Now – as the Governor of California encourages people to cover their faces when they go out and health workers continue to sound the alarm about the lack of protective equipment – a lot has changed.
The hope that the hot summer weather will end the pandemic also seems to be fading.
“We are learning more about this new virus every day,” said a WHO update.
Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said on Friday that people should cover their noses and mouths.
“Due to recent information that the virus can actually spread even when people are talking rather than coughing and sneezing, the best part of the value is that when you are away and you cannot keep that distance 6 feet, to wear some kind of face covering. “
People who have contracted the virus but do not yet have symptoms like coughing and sneezing can be contagious, according to the WHO.
The time between infection and symptoms is usually five to six days, but can be up to two weeks, allowing the virus to spread silently.
This is called “pre-symptomatic transmission” and this has been documented, said the WHO.
While WHO remains skeptical of “totally asymptomatic transmission” – the spread of the disease by people who never develop symptoms – such cases “have been reported as part of contact tracing efforts in some countries “, did he declare.
Transmission can be as simple as talking and breathing.
Just spread through conversation?
“This letter answers your question about the possibility that the SARS-CoV-2 virus can spread through conversation, in addition to sneeze / cough droplets,” said a letter to the office of President Harvey V. Fineberg, Chairman of the Standing Committee of National Academies of Science, Engineering and Medicine on Emerging Infectious Diseases and 21st Century Health Threats to the Nation.
“Currently available research supports the possibility that SARS-CoV-2 can spread via bioaerosols generated directly by the exhalation of patients,” he wrote.
A recent study at the University of Nebraska Medical Center has shown the widespread presence of viral RNA in isolation rooms where patients with COVID-19 are receiving care.
“It should be noted that the air collectors positioned more than 6 feet from each of the two patients gave positive samples for viral RNA … as did the air samplers placed outside the patients’ rooms in the hallways, ”wrote Fineberg. “The personal collectors carried by the samplers were also positive, even if the patients did not cough in the presence of the samplers.”
A study after the Hong Kong SARS epidemic in the early 2000s confirms the potential for transmission via bioaerosols, he writes.
“In this study, the considerably increased risk of infection for residents on the upper floors of a building that housed an infected person told researchers that an infection pattern was compatible with an upward plume of contaminated warm air.”
A recent study, but not yet peer-reviewed, from Hong Kong found high concentrations of virus in rooms where doctors and nurses remove their personal protective equipment after treating COVID-19 patients, he said. he writes. This suggests that the virus can be restarted by removing clothing, cleaning the floors, or moving staff.
“Individuals vary in the extent that they produce bioaerosols through normal breathing. This can affect the efficiency of transmission … from different infected but asymptomatic individuals. “
More research is needed on the spread of the coronavirus during breathing and speech, he wrote.
Summer may not help
The Huai’an, China public men’s bath – about 435 miles northeast of Wuhan – has a swimming pool, showers and sauna.
It’s big – about 3,000 square feet, the size of a comfortably sprawling ranch house – and stuffy, with a temperature of 77 to 104 degrees Fahrenheit with a humidity of around 60 percent.
What has happened there suggests that the coronavirus is much more robust than many expected – and that it cannot be quelled in the heat of the coming summer.
On January 18, a man who went to Wuhan went to the bathing center and showered. The next day, he developed a fever. On January 25, he was diagnosed with COVID-19.
“The next seven patients showered, used the sauna and swam in the same center on January 19 (patients 2, 3 and 4), January 20 (patient 5), January 23 (patients 6 and 7) and January 24 (patient 8), “says an infectious disease research letter published March 30 by the Journal of the American Medical Association.
“The symptoms associated with COVID-19, including fever, cough, headache and chest congestion, appeared between 6 and 9 days after the visit to the bathing center. Patient 9 worked in the bath center and experienced his appearance on January 30. “
The infection in all patients was confirmed by tests.
“Previous studies have shown that the transmission rate of a virus is significantly reduced in an environment with high temperature and high humidity. However, judging by the results of this study, the transmissibility of (COVID-19) did not show any signs of weakening in hot and humid conditions. “
Advice for the public
As scientists try to unravel the mysteries of the virus, the advice to those who try to avoid it remains the same:
Wash your hands often and thoroughly. Avoid touching your face. Cover your coughs and sneezes. Stay at home. And when you go out, move at least six feet away from others.
Now, the use of face masks or bandanas to cover the nose and mouth – which authorities say could trap contagions near the face – is encouraged, and many wear gloves and also cover their eyes.