Is Omicron airborne? Dr. Bonnie Henry weighs in

Omicron is spreading fast and can be transmitted through 'aerosols,' says B.C.'s top doc

Dr. Bonnie Henry urged British Columbians to not get a COVID-19 test if they do not have symptoms, as testing is at capacity. | Government of B.C. / Flickr

Provincial health officer Dr. Bonnie Henry says airborne transmission of the Omicron coronavirus variant is possible, but information gathered to date does not indicate it spreads as widely through the air as measles and chicken pox.

Henry began a Christmas Eve morning press conference by stating Omicron is transmitting so fast it has overwhelmed testing capacity in B.C. and people with symptoms will need to assume they have it, if they cannot access a test.

To that end, Glacier Media asked if Omicron is airborne, a characteristic of the virus she has previously been reluctant to prescribe to other virus (SARS-CoV-2) variants, and one that can result in different measures of transmission prevention.

Henry did not say the virus is now outright airborne but replied that “aerosols become more important for the higher transmission variants like Omicron.”

Aerosols are breathing particles that float in the air, whereas droplets are larger breathing particles that tend to drop to the ground within two metres, according to the B.C. Centre for Disease Control. If the virus exists in aerosols, it can thus spread more easily in the air and is considered airborne.

Henry elaborated on her explanation: “I think when, you know, you look at COVID, all of SARS-CoV-2, which in various different forms it’s been transmitted through the air, absolutely. We’ve said that from the beginning. But the relative importance of the different size of droplets depends on the infectiousness of the different strains, so it becomes much more important to have protection against those aerosols, those smaller droplets and, really, it’s a combination of physics.

"So, if a smaller droplet, an aerosol, has less virus in it but if that virus is more infectious, you can get infected with the smaller droplets. When we saw [the virus] early on, you needed a larger dose of the virus, so it was much more important in protecting yourself from the larger droplets,” she explained.

The Public Health Agency of Canada is also not saying COVID-19 spreads entirely through the air, but is transmitted by a combination of factors. On Dec. 23, the agency stated: “Evidence on the transmission of SARS-CoV-2 virus has advanced rapidly and continues to emerge. Respiratory fluids continue to be the primary mode of transmission for COVID-19 via large respiratory droplets and small aerosol particles.”

Canada's Chief Public Health Officer Theresa Tam was more clear on Nov. 12, before Omicron. "Importantly, we’ve learned how the virus can linger in fine aerosols and remain suspended in the air we breathe," said Tam on Twitter, when the Delta variant was spreading.

Tam said this week single-layer cloth masks, which typically act against large droplets, are ineffective against Omicron, CBC reported.

Henry said people are being infected with smaller amounts of the virus and more quickly. And transmission between people is down to as little as two days from initial exposure and infection.

“It is more highly infectious than any of the strains we have seen,” said Henry, adding there are more breakthrough infections among the fully vaccinated and more re-infections.

“We still do not have a full picture of how severe Omicron can be across the board.”

Henry has not updated guidelines on social distancing guidelines of two metres, although she stressed the need to do so. Nor has she changed any measures around workplace settings.

Henry said the new measures implemented in the past week will be monitored daily. This includes a 50% capacity limit on events with over 1,000 people. And so, for example, the Vancouver Canucks could host over 9,000 people in its stadium for Monday’s scheduled game against the Seattle Kraken.

Meanwhile, gyms remain closed and household holiday gatherings are limited to 10 vaccinated people.

Henry stressed to people not to get tested without symptoms as the daily testing capacity of 20,000 tests in the province is now at capacity.

“If you are seriously unwell, please do not hesitate to seek care immediately,” said Henry.

Hospitalization numbers, so far, are remaining relatively stable in B.C. despite the dramatic rise of reported Omicron cases, but health officials are concerned the sheer volume of infections could overwhelm the system.