Chapter 1: The Nature of Omicron

A mere 30,000 nucleotide bases are sufficient to construct the entire SARS-CoV-2 virus. These genetic components replicate within our cells, and through this process, errors occur. Most of these errors diminish the virus's effectiveness, while a select few enhance its ability to replicate—this is the essence of evolution and the genesis of variants.

This week, a new variant has captured global attention, sparking an intense international response. Countries are hastily closing their borders. What sets Omicron apart?

There has been a surge of reports and sensational news coverage surrounding this variant. While I acknowledge the rapidly changing circumstances, it's crucial to consolidate the key facts regarding Omicron.

Section 1.1: The Omicron Timeline

To start, let’s look at the timeline: the earliest known Omicron sample was collected on November 9 in Botswana, sequenced by South African scientists, and shared publicly on November 23. South Africa notified the World Health Organization (WHO) the following day. Although we are still in the early stages, cases of Omicron have already been reported in over a dozen nations, including Germany, the UK, China, Australia, and Canada. Given the rapid spread, it would be surprising if the variant hasn't already reached the U.S.

Section 1.2: Understanding the Mutations

Omicron poses concerns mainly due to its numerous mutations in the spike protein, which is a primary target for vaccines and essential for the virus's ability to infect human cells. The mutations identified indicate a mix of previously seen and novel variations.

To evaluate this variant effectively, three primary questions arise:

1. How easily does it spread?
2. What level of illness can it cause?
3. Does existing immunity (from vaccines or past infections) still provide protection?

Let's delve into the data available so far.

Section 1.3: Transmissibility Concerns

The apprehension surrounding Omicron's transmissibility has driven significant global reactions. Is it more contagious than the Delta variant? A concerning graph illustrates a rapid replacement of Delta by Omicron in South Africa.

However, it’s essential to interpret this data with caution. The Y-axis represents the proportion of cases, and the overall case numbers in South Africa were relatively low, which means a few large outbreaks could skew this data.

Recent increases in total cases in South Africa, coupled with a spike in positive test rates—from 1% to 30%—is certainly concerning.

A report from Hong Kong noted a traveler from South Africa who tested negative before departure but positive upon arrival, further indicating a potential for rapid spread. Another study in the Netherlands found a high transmission rate among travelers returning from South Africa.

Currently, it remains uncertain just how infectious Omicron truly is. Claims suggesting it could be five times more infectious than Delta are likely premature, but the potential for increased transmissibility is a significant concern.

Section 1.4: Pathogenicity of Omicron

What about the severity of illness caused by Omicron? The current evidence is still insufficient. An Israeli expert stated that, among vaccinated individuals, there were no severe cases reported. However, the limited number of known cases makes it challenging to determine the fatality rate.

It's a common misconception that viruses evolve to become less deadly; in reality, they mutate to increase their genetic presence. While reduced virulence can aid in this, SARS-CoV-2 is generally not highly lethal, with most infections resulting in survival. The evolutionary path for SARS-CoV-2 may involve mutations that enhance viral loads and improve binding to host cells.

Section 1.5: Immune Evasion and Vaccine Efficacy

Regarding immune escape, cases of mild infections in vaccinated individuals suggest some level of vaccine effectiveness remains. However, the numerous mutations in the spike protein raise concerns about potential vaccine resistance. The genetic divergence of Omicron from other variants suggests it may possess unique challenges.

We expect preliminary results from virus neutralization tests in the coming week, which will assess vaccine efficacy against this new variant. Notably, South Africa has a low vaccination rate of about 25%, so the rise in cases does not directly imply a failure of vaccines against Omicron.

Section 1.6: Future Vaccination Strategies

Should vaccines be updated? Some experts advocate for a focus on the Delta variant, given its prevalence. However, Omicron's emergence indicates that predicting future variants may be challenging.

One fact is becoming increasingly clear: as long as COVID-19 persists, new variants will emerge. Without improved global vaccination efforts, the potential for variants to evade vaccines remains a real possibility.

Description: This video delves into the data surrounding Omicron and explores whether it signals the end of the pandemic.

Description: In this video, experts discuss the current status of Omicron in the UK and whether we are past its peak.

A version of this analysis originally appeared on medscape.com.