Assume everyone infectious as 60% of cases from pre-symptomatic people, says US expert

Pre-symptomatic transmission of COVID-19 is a big concern, with estimates that 30 to 59 per cent cases are especially coming from transmission from pre-symptomatic people and less from asymptomatic people, warns expert Jose-Luis Jimenez.

A chemist at the Cooperative Institute for Research in Environmental Sciences (CIRES) and the University of Colorado Boulder, US, Jimenez was one of the six experts behind the recent assessment published in the medical journal Lancet stating strong evidence that the SARS-CoV-2 virus, which causes Covid-19, is airborne.

Speaking with IANS, Jimenez clarified that pre-symptomatic people, who are transmitting the virus do not know that they are infected, and nobody else knows that they are infected.

"They are not coughing and not sneezing. They are going about their life. They are working and meeting with their family, they are going shopping and they are infected; and they are spreading the virus. The only way to do it for a disease like this, is you have to assume that everyone you encounter is in fact infectious," he said.

He added there are three reasons why we are in a pandemic. "Because nobody has had immunity for this virus; because it is airborne, so it is easy to transmit; and because there is pre-symptomatic transmission (which is transmission without symptoms)," he maintained.

He added the SARS-CoV-1 pandemic, which occurred in 2003, had two things in common with SARS-CoV-2, the ongoing pandemic.

He said for SARS 1, two out of these three virtues were there. "It was a new virus, for which we did not have immunity and it was airborne, but it did not transmit pre-symptomatically. It was transmitted from people who were very sick and then it was very easy to identify them and to isolate them in the hospital and take precautions. For SAR1 there were 9,000 cases and for this virus there are millions. That is why pre-symptomatic transmission is very important," said Jimenez.

Terming surface transmission of virus lacking evidence, he said the Centre for Disease Control and Prevention, USA, stated that it is possible for people to be infected through contact with contaminated surfaces or objects (fomites), but the risk is generally considered to be low. He clarified disinfecting surfaces doesn't accomplish anything and this has been a reason why the pandemic has been out of control.

"The WHO bears a lot of responsibility because they really have not communicated clearly how the virus is transmitted and they refuse to accept the science. The last time they explained how the virus was transmitted was sometime in July last year. Soon, this is a year. This is scandalous," said Jimenez.

On the issue of droplet transmission, he clarified that there is zero evidence of droplet transmission for COVID-19 disease. In fact, droplet transmission has never been demonstrated directly for any disease in the history of the medicine, he added, citing that Covid is airborne since the beginning.