In this article an infectious diseases pharmacist identifies five things for pharmacists to know about the Omicron variant of SARS-CoV-2.
Authored by: Timothy P. Gauthier, Pharm.D., BCPS, BCIDP
Article Posted 20 December 2021
As the SARS-CoV-2 pandemic moves into 2022 the concept of “many good questions, few good answers” remains a theme. Until recent weeks I was following UK data which seemed to suggest that B.617.2 sub-lineage AY.4.2 was going to be next in line after the Delta variant to become the predominant variant in circulation. However, now it is clear Omicron (B.188.8.131.52) has become the next “it” variant.
As an infectious diseases pharmacist who follows the literature and emerging COVID data closely (mostly using Twitter), I thought it might be helpful to compose a post that discusses a few things for pharmacists to know about the Omicron variant of SARS-CoV-2.
Note however, the content on this page may be quickly rendered out-dated or inaccurate as things continue to evolve. Heck, some of this may be obsolete in the 2 hours between writing the introduction and the final thoughts! That stated for your consideration, here are a few things for pharmacists to know about the Omicron variant…
1. Omicron is everywhere in the United States – and it’s now the predominant variant in the country
Today CDC released new data on the prevalence of variants across the country. From the last report to this one the Omicron has absolutely exploded in frequency. The Delta took weeks to become predominant. Omicron has done it in what seems like 10 days. Omicron is now at 73.2% in the US.
You can see the variant proportions in your part of the country here from CDC. By convention the data we have available from lab tests lags behind what is happening real time, so you can use the NOWCAST function to approximate where we are today. You can also view and drill down into historical data.
Shown below, in region 4 for example, Omicron is now 95% of the detected variants. This is an enormous change from just two weeks ago when NOWCAST reported it to be 0% for region 4.
All this considered, Omicron is something we all need to be concerned about and we need to worry about it now.
Orange = Delta Variant
Purple = Omicron Variant
Screenshot captured 12/20/2021 from CDC.gov
2. Some COVID monoclonal antibodies do NOT appear to work against Omicron
In the latest iteration of the NIH COVID-19 Guidelines the below table was released. This and other data that have been published now indicate that neither bamlanivimab/etesevimab (the Eli Lilly product) nor casirivimab/imdevimab (the Regenron product) are useful versus Omicron.
The bamlanivimab/etesevimab Fact Sheet for Healthcare Providers has yet to be updated with Omicron susceptibility information. However this document states “Bamlanivimab and etesevimab are not authorized for use in states, territories, and US jurisdictions in which the combined frequency of variants resistant to bamlanivimab and etesevimab exceeds 5%”. The casirivimab/imdevimab Fact Sheet for Healthcare Providers also has not been updated to include Omicron susceptibilities. This fact sheet does not have an objective cut-point for ceasing use due to resistance, but does state that healthcare providers should review data on circulating variants to make treatment decisions.
Interestingly, a few days ago the Public Health Emergency website published a posting that appears to indicate a rise above 20% resistance would be an acceptable cut-point to stop using bamlanivimab/etesevimab or casirivimab/imdevimab. With Omicron well-exceeding 20% in so many parts of the country now, it certainly calls the clinical utility of these to therapies into question. It seems imminent that there will be more releases on this topic in the coming days (if not hours!).
With the Delta variant many healthcare organizations were able to treat thousands of patients with casirivimab/imdevimab or bamlanivimab/etesevimab. The data indicate these treatments helped to prevent a lot of hospitalizations and emergency room (ER) visits due to Delta. With these two options off the table to help prevent progression of disease in high risk patients, I worry about what impact Omicron is going to have on hospitals in the coming weeks.
Screenshot captured 12/20/2021 from https://www.covid19treatmentguidelines.nih.gov/
3. Some monoclonal antibodies DO appear to work against Omicron
As shown in the table above it appears sotrovimab (from GlaxoSmithKline) will retain activity versus Omicron. Also in a news release, AstraZeneca announced their product tixagevimab-cilgavimab (Evusheld) will work against Omicron.
While sotrovimab has an FDA Emergency Use Authorization (EUA) for treament of mild-moderate COVID-19, tixagevimab-cilgavimab has an EUA for COVID-19 pre-exposure prophylaxis. Thus, if someone falls ill with COVID-19 from Omicron, it will be sotrovimab that they will want to reach for, especially if they have substantial risk for progression to severe disease.
Unfortunately, the availability of sotrovimab appears to be severely limited at this time. Weekly allocation of the COVID monoclonal antibodies are listed here. For the week of December 17th, just 55,002 doses are being allocated in the US. You can drill down to your state and for example the state of Florida (which has a population of ~20,000,000) will get just over 1,000 doses. Having a newer EUA, the distribution of tixageviab-cilgavimab is a bit less clear, but the product should start to become available soon.
For the doses of either product that do become available, it will be important to use them wisely. For guidance on prioritizing patients, this section of the NIH COVID guidelines may be helpful.
As we consider these monoclonal antibodies for Omicron, I have been wondering one thing. If the benefit of these therapies is in reducing the rate of ER visits or hospitalizations and the Omicron variant turns out to cause a lower frequency of progression to severe disease, how much benefit can they really have against Omicron? Will the number needed to treat be higher for Omicron? I am certainly interested to learn more about this.
4. Molnupiravir (Lagevrio) and nirmatrelvir/ritonavir (Paxlovid) are on the horizon
Molnupiravir (Lagevrio) was approved for use in the United Kingdom back in the beginning of November 2021. In the US at the end of November 2021 an FDA advisory panel called the Antimicrobial Drugs Advisory Committee (ADMAC) voted 13-10 in favor of approving Merck’s molnupiravir under an FDA EUA. Most EUAs have followed fairly quickly after such votes. It is now 3 weeks since the vote and still no EUA has been released. The outlook on molnupiravir is unclear at this time. Colleagues have shared rumors an FDA EUA will be coming soon, but I have also heard concerns over associated mutagenesis with potential safety implications for children or pregnant women may be the cause for lack of movement.
According to Merck, molnupiravir is likely to be active against Omicron. If molnupiravir does get an FDA EUA, pharmacists will certainly be front-and-center for answering drug information questions on this new antiviral COVID pill.
Pfizer announced that their SARS-CoV-2 antiviral pill nirmatrelvir/ritonavir (Paxlovid) retains activity against Omicron in a December 14th news release. They have also indicated they are seeking an FDA EUA. To date I have not seen any information on an FDA ADMAC meeting to discuss this antiviral (which by the way has a different mechanism of action than molnupiravir).
With the ritonavir component, you can be sure drug-drug interactions will be a major concern if nirmatrelvir/ritonavir gets an FDA EUA. Again, expect pharmacists to be front-and-center for answering drug information questions about this other new antiviral COVID pill.
5. Vaccines continue to have an important role
On December 8th Pfizer shared preliminary data which indicated boosted people have antibodies that can neutralize the Omicron variant. Just today Moderna shared similar encouraging information about boosters being protective against Omicron.
Last Thursday CDC and ACIP down-graded their preference of the J&J vaccine to below that of the mRNA vaccines.
While who to give which vaccines to and when remains a topic of discussion, it is clear that vaccines continue to have a major role in stemming the progression of this pandemic, including for Omicron. In turn, pharmacists will need to continue to be familiar with CDC and EUA guidance on the COVID vaccines. The CDC interim clinical considerations webpage should prove a helpful resource for navigating these waters.
Pharmacists in all practice settings continue to play a critical role in the prevention and management of COVID-19. Omicron is new. Things are complicated. We have a lot to learn. As we go through this, I believe it is important that we be open to change as new data emerge and we need to continue to try to accept the fact that we will have many good questions, but few good answers. Yet despite these challenges, through working together we can overcome this!
DISCLAIMER: The views and opinions expressed in this article are that of the author and do not necessarily reflect the position, policy, or view of any past, present, or potential future employer.
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