Travelers became infected in the corridor of the Covid-19 quarantine facility, New Zealand research finds

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By Maggie Fox, CNN

A traveler isolated for Covid-19 at a quarantine facility in New Zealand managed to infect three other people in a hallway, researchers reported Thursday.

CCTV footage, genetic testing and careful contact tracing show that the only conceivable way the virus could have passed from room to room was in the air that escaped when the two doors were briefly open, the researchers said.

It’s a demonstration of how the virus can be spread – and how effective vaccines are. The only person who escaped the infection was fully vaccinated and never tested positive, despite being in the same room with four other infected people for weeks.

The two groups of travelers arrived in New Zealand in mid-July, as the Delta variant of the coronavirus swept the world. A single traveler from the Philippines tested positive during quarantine and was placed in a converted hotel called a managed isolation center. A group of five from the United Arab Emirates also arrived, were quarantined, and then one member of the group tested positive, so they were placed in the same facility, across the hall from the first traveler.

No one was allowed to leave either room, and the doors were only open for nurse checks and food deliveries – but the doors weren’t meant to be open at the same time. Nonetheless, it did happen, according to Andrew Fox-Lewis of the Manukau County District Health Council in Auckland, New Zealand, and his colleagues. “Security camera footage revealed four brief episodes of simultaneous door opening during Person A’s infectious period,” the team wrote. Each time only lasted a few seconds.

Three other people in the group of five were infected, but genetic testing indicated that their infected companion was not the source. It was the traveler from the Philippines – their virus had the same DNA fingerprints.

Airborne transmission through the corridor is the most plausible explanation, the researchers said. “These findings are of global importance for public health interventions and infection control practices related to coronavirus disease,” Fox-Lewis and colleagues wrote in the journal Emerging Infectious Diseases.

“It was found that Person A did not leave the room at any time during their infectious period… and did not leave the room to exercise until after the infectious period, starting July 28. (after people B and C have already tested positive), ”the team said. added. It is possible that this traveler breathed an infectious virus into the air in their bedroom and that air blew in and through the hallway when the door was opened.

New Zealand authorities had tried to prevent this with extractor fans and air purifiers, but the system may have failed when the doors opened. “There was no ventilation system connecting separate rooms. The rooms had exterior windows that could be opened freely by occupants, ”the researchers noted.

“Our results support the hypothesis that during episodes of simultaneous door opening, airborne particles in Person A’s room quickly diffused in a concentration gradient, through the hallway and in parts of the BCDEF group, “the team wrote.

One person escaped the infection: the vaccinated traveler. “Despite sharing a room with four other people infected with SARS-CoV-2 confirmed by PCR, person F has never tested positive for SARS-CoV-2 by (PCR test), testing negative July 14, 18, 21, 27, 29. , August 31 and 8, 14, 16 and 23, ”the team wrote.

“Person F had received two doses of the Pfizer-BioNTech COVID-19 vaccine, but no other member of the travel party had been vaccinated. “

This is not the first time that researchers have documented an infection via the hotel hallway. Coronaviruses can be carried in tiny airborne particles called aerosols, and they infect people when inhaled.

Earlier in December, a team in Hong Kong reported that one fully vaccinated traveler infected with the Omicron variant infected another staying in a quarantine hotel there.

“Case A arrived in Hong Kong from South Africa on November 11, 2021 and case B arrived in Hong Kong from Canada on November 10, 2021. Both cases had already received two doses of the vaccine,” Leo Poon of the University of Hong Kong and his colleagues wrote, also in the journal Emerging Infectious Diseases.

“When they arrived at Hong Kong airport, the two patients stayed in the same quarantine hotel and had rooms across the hall on the same floor. “

Hong Kong is forcing many international travelers to quarantine themselves at designated hotels for three weeks.

“No items were shared between the rooms and no other person entered either of the rooms,” the team wrote.

“The only time the two quarantined people opened their respective doors was to collect food that was placed right outside each room’s door. The only other time they could have opened their doors would be for (PCR coronavirus tests), which were done at three-day intervals. However, since these two case-patients arrived a day apart, it is unlikely that they will be tested on the same day, ”they added.

Genomic sequencing clearly showed that the two travelers were infected with almost identical versions of the same Omicron virus, the researchers said. CCTV footage showed the two remained in their bedrooms, as required.

“Airborne transmission through the corridor is the most likely mode of transmission,” they concluded. “None of the 12 people staying in adjoining rooms on the same floor during the study or the affected hotel staff tested positive in repeated tests for SARS-CoV-2.”

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