… however, WHO and CDC updates guideline on how the virus spreads

Younten Tshedup

Almost 14 months after Covid-19 was declared a pandemic, the SARS-CoV-2 virus, the pathogen that causes Covid-19 is far from being completely understood.

A major hurdle in understanding the virus is due to the rapid mutation it has undergone so far in producing new variants.   With every significant mutation, the transmissibility and severity of the virus increases.

Countries suffering new waves of the pandemic are as a result of these new variants, which are classified as ‘variants of concern’ by the World Health Organsation (WHO).


How Covid-19 spreads   

Ever since the outbreak of the disease in China in December 2019, the mode of transmission of Covid-19 from one individual to another has been a matter of intense debate.

Initially, the WHO maintained that Covid-19 primarily spread through droplets expelled from the nose and mouth of infected persons.  However, mid-way last year, more evidence emerged that indicated that the novel coronavirus could possibly be airborne.

For a virus to be airborne it would mean that the pathogen could remain and be carried through the air. Scientific evidence suggests that the SARS-CoV-2 virus can hover in the air for hours in indoor spaces, infecting people as they inhale.

WHO representative to Bhutan, Dr Rui Paulo de Jesus, said that the global health body had already acknowledged the possibility of airborne transmission through aerosols that remain floating in the air for a longer time.

He said that the possibility of transmission through aerosol was more in closed door settings with crowded people and poorly ventilated rooms for a certain period of time including certain medical procedures like intubation that generated aerosols and in gyms.

“We had already acknowledged this possibility which is why the additional recommendations such as maintaining good ventilation during meetings and at homes were added to our previous recommendations,” said Dr Rui.

The global health body in a recent update on how the virus spreads, stated that the Covid-19 can spread from an infected person’s mouth or nose in small liquid particles when they cough, sneeze, speak, sing, or breathe. These particles range from larger respiratory droplets to smaller aerosols.

Also, the US Centers for Disease Control and Prevention (CDC) updated its guidance on Covid-19 on May 7, saying that inhalation of these smaller particles is a key way the virus is transmitted and put it on top of its list of how the disease spreads.

However, Dr Rui said that besides considering and acknowledging the possibility of airborne transmission, it was difficult to confirm anything for now.  “Epidemiologically, science has to be able to say that it is happening for real. And to do this, you must capture the aerosol, check if the virus in it is still viable and alive in a laboratory. This is not easy.”

He said that the WHO’s position on some public health subjects gets delayed for the want of more scientific evidence. “We can’t just make a statement based on assumptions. WHO continues to look at all evidence and analyse the data. This is why, for now, our statement is that airborne transmission is a possibility.”

Some of the health officials Kuensel spoke to said that airborne transmission of Covid-19 had been considered from the beginning of the pandemic. However, in what proportion the transmission took place was unknown, said an official.

“The way people are getting infected, especially an entire family from one single infected individual clearly shows the virus is airborne in an indoor setting,” said the official.

He however, added that airborne transmission did not mean that virus was freely moving in the open air outside. He explained that if an infected person was freely walking near Changlimithang Stadium, the virus expelled from him or her via cough, sneeze, or spit will not travel through air and infect someone at the archery range.

“But then this would change if a large crowd is gathered at the stadium or the archery range. With more people in a particular location, the virus can effectively travel from one person to another and be able to infect a large number,” he said. “People act as a bridge for the virus to get to another host. This is why in a large gathering airborne transmission is possible.”

The prevalence of the virus in the community would also determine the rate and mode of transmission, said another official. “Like in India, when hundreds and thousands test positive daily, the virus has extensively spread. Assuming every third person is infected, airborne transmission is easy in such settings.”

Despite vaccination, using face masks, avoiding crowds and maintaining physical distance and regularly washing hands is the best defense against the virus, said Dr Rui. He added that these are proven measures that will save individuals, families and communities from the invisible enemy.