Recently, the story of several households living in an apartment complex in Ho Chi Minh City contracting Covid-19 while being in close proximity, on the same vertical axis, and within the same block has been widely discussed on social media forums and in various residential groups. What is the truth?
Residents in the apartment complex have been sharing information that Covid-19 can spread through skylights or ventilation ducts in buildings and apartments. The evidence presented is that in Apartment Complex A, the units with individuals testing positive for SARS-CoV-2 are all aligned vertically across the floors. Some “netizens” even “collected” and analyzed how the virus travels through the ventilation ducts from lower floors to upper floors.
One social media account wrote: “In South Korea and Taiwan (China), it has been confirmed that the SARS-CoV-2 virus is very small in size, with a single-stranded RNA genetic code packaged in a thin lipid membrane. Therefore, when released into the air, these viruses often exist as tiny particles. In windy and sunny conditions, these tiny particles quickly disperse, causing the virus to “dissolve,” as the SARS-CoV-2 virus is not a living entity and requires a host to survive and replicate. Thus, in open areas that are well-ventilated and sunny, there will be fewer viruses present. In contrast, apartment complexes, where many people live in close quarters and ventilation is poor, can allow the SARS-CoV-2 virus to be released into the air as tiny particles when an infected person sneezes, coughs, or talks. The SARS-CoV-2 virus can then spread through the ventilation system up or down depending on the season.”
This, according to infectious disease experts, is never a reasonable scenario.
Currently, there is no scientific research confirming that the virus can spread through the ventilation system in apartment complexes.
Dr. Truong Huu Khanh, one of the infectious disease experts in Ho Chi Minh City, stated that the skylight in an apartment complex draws air from above into the apartments, and cannot naturally blow air back up from the apartments. There is also no possibility for an infected person to breathe into the ventilation duct. “Transmission can only occur when an infected person moves into the hallway, the skylight area, and uses the elevator,” Dr. Khanh said.
Dr. Nguyen Hong Tam, Deputy Director of the Ho Chi Minh City Center for Disease Control, also addressed this issue. According to Dr. Tam, there is currently no scientific research confirming that the virus can spread through the ventilation system in apartment complexes. “People might have heard that the Delta variant can linger in the air, leading them to infer that the virus can spread through the common ventilation system of apartments. However, this is not substantiated. The Delta virus spreads through droplets and can survive in the environment but not for long. In this hot weather, if the virus is released into the air, it will also be quickly eliminated by the heat,” Dr. Tam further explained.
Previously, in an online Q&A session, Dr. Le Quoc Hung, Head of the Tropical Diseases Department at Cho Ray Hospital, stated that the spread of the virus also depends on the airflow, and we cannot prove that apartments can transmit Covid-19 to each other through the ventilation system. “Only direct contact between individuals can lead to virus transmission,” Dr. Hung said, citing the example of two adjacent apartments, one with an infected person in isolation while the other remains careless, still going into the hallway to breathe air, which could easily lead to infection.
Transmission can only occur when an infected person moves into the hallway, the skylight area, and uses the elevator.
Dr. Hung added that if a house has two rooms, one of which is isolating an infected person, but the doors are common, the virus can spread because the atmosphere is interconnected, allowing the virus to travel through the air and airflow.
“Unless the opposite apartment has an infected person, and your apartment’s window faces the opposite apartment or the shared hallway, the window should be kept tightly closed. Otherwise, during the time an F1 or F0 is isolating at home, windows should be kept open frequently to allow for adequate oxygen for easy breathing and to help dilute the viral load in the room,” Dr. Le Quoc Hung advised.
