Tracer gas was used in an unusual experiment recently at a hotel in Taiwan that had been turned into a quarantine center for patients who had been exposed to COVID but exhibited no symptoms of infection. The purpose was to track down the sources of the virus’s transmission after a small outbreak was discovered in the hotel.
The findings, which were published in the journal Emerging Infectious Diseases, demonstrate how the Omicron versions of the virus are more easily spread from one host to another by exploiting weak air currents.
The SARS-CoV-2 virus has been found to transmit swiftly and widely from person to person. Aerosols, which are tiny particles of respiratory secretions packed with the virus that can float in the air for a while, have been proposed as the main transmission pathway. In the correct environment, however, they can disperse over large regions, up to two meters in circumference. This has been observed during choir rehearsals and in bars.
WHO and the (CDC) have both acknowledged that aerosol transmission is a potential route of infection when people are crammed together inside or when ventilation is suboptimal for the number of individuals and the location.
From July 2021 onwards, visitors to Taiwan were were required to show proof of negative results on a COVID-19 test in under three days of booking their flight. In addition, a negative follow-up test meant ending the mandatory quarantine period of 7-10 days. During the Lunar New Year on February 1, there was a large influx of Taiwanese returning home from abroad in the weeks leading up to the holiday. As a result, there was a rise in the demand for hotels that might serve as quarantine areas for visitors.
Because of this, many regular hotels became quarantine accommodations. However, the hotels were not built to prevent the spread of disease; thus those who had been isolated were put at risk. The virus-carrying aerosol has been shown to go through walls and floors in residential buildings before.
In December 2021, eight travelers contaminated with the Delta variety caused the first of many breakouts at this type of hotel. Afterward, there were at least 15 further outbreaks, the last of which was documented on December 29th, 2021. During the quarantine period, three people who were living in different rooms on various floors contracted the illness.
Assuming that an infected traveler from New York, USA, was the source of the most recent three-case outbreak, the Taiwanese CDC looked into the matter.
The quarantine hotel’s noncontact procedures and PPE were tested for efficacy. Tracer gas was utilized to investigate the potential for aerosol transfer between rooms, and the hotel’s ventilation system and building layout were also studied. The air quality meter picked up the ethanol tracer gas.
What did this research prove?
Negative tests showed that all three patients in our inquiry did not have the virus either before or after they arrived in Taiwan. Throughout their time in the hospital, everybody was locked up in their respective rooms. As far as the researchers are aware, no other hotel employees or patrons had a good experience in the month prior to the current study.
The first confirmed case originated in China, was isolated in room 611, and showed no signs of illness until day 14 of quarantine (December 28, 2021). The following day, everyone staying in these two hotel rooms were given a test to see if they were infected with the virus.
The second patient, who is being treated as the principal suspect, arrived from the United States a week after the first and stayed in room 510 for two days before the third. The first patient had received the Sinopharm vaccination and the second patient had received the Pfizer/BioNTech vaccine for a total of two doses.
The third patient was a Japanese national who had gotten a single dosage of the Pfizer vaccination and showed no signs of illness. Room 503 was where she stayed.
On December 29, 2021, the first patient isolated in room 510 became ill. Positive results from the patient in room 611 the day before prompted further RT-PCR screening on these two floors (RT-PCR). Due to this, the other two patients were identified and admitted to the hospital for treatment. All other guests from these floors were told to spend the next two weeks in quarantine at a different hotel. By the time the second phase was over, everyone had again tested negative.
The three patients all belonged to the same subdivision of the Omicron line and shared the same set of three SNPs. The strains in the three distinct samples varied by two nucleotides.
In the meanwhile, they discovered openings in the walls where pipes or wires were running or had been. Some that had been abandoned were not completely sealed off. Unsealed, cut-off sections of pipe jutted out from the ceilings of one room and onto the bathroom of the room above them. The airflow from the HVAC system provides a plausible explanation for the distribution of the aerosols in all three rooms, where they were initially detected.
When the ethanol was discharged in the index patient’s room, it was also detected inside the rooms of the other two patients. The three patient rooms and the rest of the hospital were also sampled, but the results were negative.
To the best of the investigators’ knowledge, this is the first Omicron outbreak in Taiwan that was not preexisting. Although the three incidents occurred in different rooms, the virus still spread throughout the building thanks to airborne droplets.
Quarantine hotels need to improve their ventilation
The findings of the investigation imply that there were hidden links between apparently unrelated, locked rooms. It’s possible that the virus load accumulated because of poor ventilation, and then spread to neighboring rooms through the crevices and holes in the walls and ceilings. Infection would be more likely due to the extended periods of exposure.
What this means is that there is no longer any quarantine protection for infectious diseases other than the already established rules for no-contact services and cleaning. The Taiwanese government recently surveyed all quarantine hotels for ventilation systems, uncovering common issues such as missing or damaged partition walls, limited access to outside air, and the escape of stale bathroom air into the hallway or adjacent rooms or floors.