Omicron Variant and COVID19 Update

It is almost 2 years since the SARS CoV2 virus was identified as the cause of an unusual viral pneumonia outbreak in Wuhan, China. The infection, named as COVID19, spread globally and the resultant pandemic has infected more than 260 million persons and caused more than 5.2 million deaths by the end of November 2021. In Singapore, we have just over 260,000 notified cases of COVID19 with just over 700 deaths as of November 28th 2021.

We have learnt much about the virus in the past 2 years and we now have numerous interventions to combat SARS CoV2. These include:

Preventive Measures

Non-Pharmaceutical Interventions which include face coverings, social distancing and good hand hygiene

Vaccination. Vaccine development has been accelerated and we now have preventive vaccines in Singapore that cover 2 different platforms  and these are the mRNA vaccines (Pfizer-BioNTech, Moderna) and the killed virus vaccines (SinoVac and SinoPharm). The adjuvanted protein subunit vaccine by Novavax may become available in the coming months.

Treatment of COVID19 Infection

Similar to the rapid development of vaccines against the virus, we now have numerous treatments against COVID19 infection. They may broadly be divided into:

Monoclonal Antibodies: In Singapore, we have access to Sotrovimab and Casirivimab/Imdevimab (REGN-COV2). In infected patients who are at high risk for deterioration, the monoclonal antibodies must be administered early in the illness and they are effective when given within 5-7 days of symptom onset.

Anti-viral agents: Presently in Singapore, we use intravenous Remdesivir for patients who are at high risk for deterioration or who have already deteriorated requiring supplemental oxygen. The drug is administered for 3-10 days depending on the clinical condition. We anticipate that oral antiviral agents such as Molnupiravir, Paxlovid and others may become available in the coming months under the Pandemic Special Access Route. These oral agents must also be administered early within the first few days of disease onset. In the study information provided by the pharmaceutical companies using oral agents, they have demonstrated reduction in subsequent hospitalization and death from COVID19 infection.

Other therapies: in addition to the other supportive measures, we also institute treatment to control the hyperinflammatory state that occurs in COVID19 infection and these include Dexamethasone, Tocilizumab, Baricitinib etc.

Treatment guidelines and protocols are now well established for management of COVID19 infection.

COVID19 Variants and Omicron

The SARS CoV2 virus has continued to evolve. The delta variant which became dominant since early 2021, was more infectious than the original Wuhan strain with Ro estimated as high as 5-7. In many countries, there were more COVID19 infections in 2021 than 2020.

Just as we thought we had the pandemic under control with improved vaccination rates, the recently discovered Omicron strain (B.1.1.529) has been designated a “variant of concern” by WHO.

The many mutations (32) detected in the spike protein of the Omicron strain has sparked off worries that it will start off another wave of infections. (In comparison, the delta strain had 9 changes in the spike protein). Some of the major considerations which relate to the mutations are:

  1. The mutations may result in the virus being more transmissible and cause more severe disease. The number of COVID19 infections with the Omicron strain have increased rapidly in South Africa and Botswana. The fear is that it will rapidly “take over” as the predominant strain. The Omicron strain has also travelled afar and has been detected in Israel, Belgium, UK, Hong Kong and Australia.
  2. The mutations may result in “ vaccine escape mutants” and cause more breakthrough infections in fully vaccinated individuals. The pharmaceutical companies are now studying if vaccine re-formulations will be required
  3. The mutations may impact on the current diagnostic tests used. This is being rapidly evaluated and NCID’s preliminary evaluation is that our current tests should be able to diagnose the Omicron strain.
  4. The mutations in the spike protein may impact on the efficacy of the monoclonal antibody treatment. This is being studied and our current treatment protocols may need to be updated for patients infected with the Omicron strain.

There is still much more that we need to know and we will have to wait for more scientific data to tailor the appropriate response to this new variant. In the absence of clear scientific data, the immediate response to this new strain should be one of extreme caution and to reduce the risk of possible strain importation. This will buy sufficient time for a scientifically sound and robust response to be implemented to this and any future variants of concern.