Closed sites and low ventilation are key factors for COVID-19 transmission

In the middle of the coronavirus pandemic, return to full normality is increasingly a challenge for government and health authorities. Factors such as enclosed rooms, low ventilation and long cohabitation times are key elements to continue the spread of COVID-19.

Recent scientific studies in China explained how COVID-19 contagion occurred in a Restaurant, Bus and working room, concluding as risk factors: multiple and close contacts, poor ventilation and prolonged time in social interactions. The latter is an essential condition for contagion to occur, which leads us to ask ourselves the following question is it possible to return to class or face-to-face work in the short term?

In this line, Dr. Catterina Ferreccio, Epidemiologist, researcher at the Centre for advanced chronic diseases (ACCDIS) Pontifical Catholic University and a member of the Advisory Council of the Ministry of Health, said "We're recently entering the coldest time of the year, this brings with it that people are closer, there is little ventilation and stay in enclosed space. According to studies and experiences of northern hemisphere countries, the spread of the virus has been significantly reduced now that they are in summer". This leads us to say that the virus apparently survives better in cold and dry environments and less in hot and humid temperatures, indicated the epidemiologist.

By these dates, it is very common to use air conditioning and the closing of windows, which is one of the biggest dangers in a back to class or office jobs. "We would have constant airflow, closed places and contact for a certain time in the same place. It was recently shown that maintaining a minimum of 53 minutes of overlap in air conditioning causes the spread of the virus, time that corresponds to approximately one hour of class", commented Mario Chiong, University of Chile academic and ACCDIS researcher.

Considerations for a return to face-to-face classes

The epidemiology expert said that back-to-school is a complex decision where a number of requirements need to be taken into account that should be met, starting with teachers, because these are the ones most at risk of contagion in a classroom. "Ideally, you'd have a diagnostic test when you enter and find out if any of them are immune to the virus, whereas for those ing out of antibodies, you should keep a surveillance of symptoms and search for viruses, for example, filling out a survey every time they enter classes", said Dr. Ferreccio.

As for children, surveillance should also be applied by its agents and/or representatives, where systems and possible contacts are reported with people positive to the virus.

However, it's not the only challenge we'd face with a back to class during the pandemic. Social distance is another important factor where every child must keep 2 meters among his peers, which is very complicated for the little ones, emphasized the doctor, who also added that students should be prevented from swapping pencils, toys and other materials.

On the other hand, as already mentioned above, time plays a key role in the spread of the pandemic, for this reason, ideally they would be the least amount of hours at school, "you have to try to keep some of what has been achieved with distance classes. Exposure will decrease depending on duration and closeness”, emphasized the expert.

As general recommendations for a return to school or face-to-face work, academic Mario Chiong noted "it is necessary to meet the proper social estrangement, the correct use of masks, physical space ventilation, reduction of the day and adequate distribution of posts".

To finally, Dr. Ferreccio said that, in an ideal scenario it would be best to resume classes when there is a significant drop in the increase in new cases, "i.e., wait at least a full week where the transmission curve was observed to stop".

However, both specialists agreed that taking into account China's background, it is also necessary to study more carefully the measures and conditions that must be taken for an optimal return to class.