Here Comes Omicron, Here Comes Omicron …

The news has been full of reports of the Covid-19 Omicron ever since it was declared a variant of concern by the World Health Organization (WHO) on November 26, 2021. There has been a lot of new information every day and many changes to some of the earlier reports. The following is an excellent summary and assessment that is complete and up-to-date to December 18. Dr Andrew Morris is a professor of Infectious Diseases at the University of Toronto and a member of the Ontario COVID-19 Science Advisory Table. It is worth reading all of this and perhaps signing up for his regular mailings.

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Here are some of the important highlights.

• The early data from South Africa suggested that Omicron might be less severe than Delta because hospitalizations from Omicron were less frequent than Delta but this is not being borne out in Denmark, and probably will not be true in Canada and the U.S.
• There are several other reasons why the progress of Omicron in South Africa may be very different than here. 
• Omicron is spreading rapidly around the world. Besides South Africa, UK, and Denmark, there are  steep Covid case increases in Norway, France and Spain.

What should you do?

Besides the recommendations made by Dr Morris in the article above, you should make sure you are using an effective mask. The typical surgical mask is only about 50% effective because it is not very tight fitting and there is a lot of space where virus particles in the air can get through to your mouth and nose. An N95 mask on the other hand is 95% effective. Cloth masks shouldn’t be used at all. 

One reason that Omicron may be so much more transmissible than Delta may be because it spreads more readily through the air. This could be because people who have Omicron may be expelling larger amounts of virus particles than with Delta or it could also be that the aerosol particles may be smaller, circulate more quickly and stay in the air longer. The evidence now suggests that Covid-19 is primarily spread through infectious aerosols that people breathe in.
Preliminary data hint at what makes Omicron spread so readily.

The previous blog article highlighted how ventilation is a big risk because there are no standards, from small spaces like restaurants to large spaces like factories and warehouses. Ventilation is very important for removing the small aerosol particles in the air. The larger droplets that contain the virus tend to drop out of the air within 6 feet shortly after being exhaled. Social distancing in enclosed spaces is not enough to keep you safe; the virus aerosol particles which may circulate in the air for hours may be more dangerous than the droplets.

It is difficult to assess how well a space is ventilated without some measurement or getting a statement about the HVAC system from the building management. And you cannot assume that a newer building will be better ventilated than an older building. 
Air Circulation and Coronavirus: How to Judge a Ventilation System

You can judge if a space is small relative to the number of people in it. So a crowded restaurant with low ceilings is probably not very safe whereas a gym with high ceilings that is not very crowded may be a lot safer. On the other hand, you could get infected in an empty restaurant from aerosol particles that are still circulating from a patron who left hours before you arrived. 

Finally remember that the best way to protect yourself from Covid infection is having several layers of defense. The following illustrates this well.