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Omicron most dominant strain; makes vaccination essential

A news bulletin from Dr. Petri, our University of Virginia expert who studies the coronavirus and COVID-19 and who has been answering reader questions this fall for The Daily Progress.

Omicron is now throughout the US.

The Centers for Disease Control and Prevention has reported that omicron is now the predominant COVID-19 virus variant in the US. For the week ending December 18th omicron is over 70% of all sequenced SARS-CoV-2. This happened almost overnight, from less than 1% of all isolates in the week ending December 4th. This is testament to how incredibly infectious omicron is, especially compared to delta which had been the most infectious variant until now.

Where did it come from?

Omicron most likely originated from a single person who was infected in 2020, who has since that time been harboring the virus (likely due to immunocompromise), allowing the virus to amass a large number of mutations that make it both evade anti-Spike antibodies and promoting its infectiousness. It was first identified in Botswana and South Africa at the beginning of November and quickly became the predominant variant there (as it now is today in the UK and the US).

What are the symptoms of omicron?

Omicron, not unlike delta, can present with common cold symptoms (coughing, sneezing, runny nose, fatigue) or with more severe symptoms of fever and shortness of breath. Any of these symptoms is reason to isolate yourself at home until tested for COVID-19. This will help to prevent exposing others. And of course one needs to remember that infections can occur without any symptoms, so if you are not fully vaccinated and boosted you should quarantine if you have a known exposure to someone with COVID-19.

People who have received the Pfizer or Moderna vaccine and booster are not only protected from moderate to severe COVID-19, but are much less likely to have asymptomatic or mildly symptomatic infections as well. They also are not required to quarantine themselves after a known exposure.

Is omicron less severe?

Early results from South Africa are indicating that hospitalizations are at about a third of what happened with delta. Whether this will hold true is not clear as it is still early in the omicron wave of the pandemic and the population of South Africa is younger and therefore more resistant to severe infection than that in the US. But let’s hope for the best, while planning for the worst.

What treatments work for omicron?

Right at this moment very little. Our goal for omicron should be prevention and not treatment, as today an ounce of prevention is worth a pound of cure. The Pfizer pill for COVID-19 that blocks the viral protease (preventing assembly of new infectious virus) is up to 90% effective at preventing COVID-19 severe enough to result in hospitalization. It however will not be immediately available as it is just going into mass production. Merck also has an antiviral pill that inhibits the ability of virus to make copies of its genome, which while less effective in clinical trials than the Pfizer medicine should also be available soon. In the interim the only anti-Spike monoclonal antibody known to work for omicron is sotrovimab which is in short supply (only 55,000 doses for the entire country available this week from the CDC).

What does this mean for masks, social distancing and hand washing?

We need to redouble our efforts to reduce our exposure, as omicron is incredibly more infectious than even delta. This means a return to mask wearing in indoor public spaces even if vaccinated and boosted, and continuing social distancing and hand washing.

What does this mean for vaccination and boosters?

Everyone ages 18 years and older who has been vaccinated (6 months ago or more for Pfizer or Moderna, or 2 months ago for J&J) needs a booster shot of either the Pfizer or the Moderna vaccine. Only with this booster is protection against moderate to severe COVID-19 (ie COVID bad enough to put you in the hospital) restored to 90%. The J&J vaccine is no longer recommended as a vaccine or a booster due to its substantially lower ability to protect against omicron.

In addition everyone ages 12 and older who has not yet been vaccinated, should immediately be vaccinated with the Pfizer or Moderna vaccines. Also important to know that prior COVID-19 infection does not provide adequate protection against omicron, and one should get vaccinated after a prior infection, or receive a booster if already vaccinated (ie if you had a breakthrough infection).

What about holiday travel?

If you are vaccinated and boosted and wear a mask, then travel over the holidays is minimal risk. My middle son and oldest daughter will be coming to visit from Oregon on Thursday and because they are boosted, and everyone in our family is boosted, I have no concerns. International travel is a bit dicier, as even the boosted vaccines may not prevent you from a mild or asymptomatic infection that could keep you isolated overseas for 10 days. I am mulling this over right now as I try to decide whether to travel to my research site in Bangladesh next month!

What about my holiday party?

An indoor family gathering where everyone has been vaccinated and boosted is fine. If there will be some at the event who have not been vaccinated and boosted, then one can do at home rapid tests the day prior to mitigate risk, or have the event outdoors. Short of that, do plan to make safe the highest risk person at the event. An elderly relative that has not been vaccinated or boosted for example is up to 100-times more likely to die from COVID-19 than a 40 year old or younger unvaccinated relative.

I am so sorry to be the bearer of bad news, but with vaccination and boosters we will do just fine with omicron. The worry is those of us who are unprotected from this most infectious COVID virus ever.


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