What Makes the Omicron Variant So Dangerous?
The WHO has confirmed that, by December 19, the Omicron variant had spread to more than 89 countries. Many epidemiologists believe that Omicron will shortly become the dominant strain of COVID-19, replacing the delta variant (which is currently the dominant coronavirus variant). Compared to Delta, Omicron is capable of multiplying 70 times faster inside the human respiratory tract.
A recent report (Dec 10) from the UK’s Department of Health also indicates that household transmission of Omicron is around 3 times higher than for Delta. The World Health Organization (WHO) designated Omicron (aka. variant B.1.1.529) a variant of concern at the end of November, and within just a few weeks, it has led to increased case rates in a number of countries.
However, amidst the rapid spread of this new variant, there are still a large number of questions that need to be answered. Although Omicron appears to have a degree of vaccine escape, the exact extent of this is unknown, as is the ability of our existing vaccines to prevent severe illness and death in those infected, whether Omicron can also reinfect those with some immunity from previous infections with Delta, the risk of reinfection with Omicron, and the effectiveness of existing treatments.
What is the Omicron variant and how dangerous it is?
The Omicron strain of coronavirus was first identified in South Africa on November 24, 2021, and the first case was detected in the UK on November 27. However, it now appears that the variant was already present in Western European countries at least a week before that. Authorities in the Netherlands have reported that they detected the variant in test samples which were collected as early as November 19.
In the US, the first Omicron case was reported on December 1, and since then the variant has spread in more than 35 states. While Delta is still the dominant strain in the US, by the middle of December, Omicron already accounted for more than 3% of the total COVID cases in the country. Preliminary data suggest that omicron has not caused many severe health complications in double-vaccinated patients in the US.
While Omicron accounts for around 90% of all new infections in South Africa, it has also been reported that two doses of Pfizer-BioNTech vaccines appeared to provide 33 percent protection against infection, but 70 percent protection against hospitalization. However, the exact reasons for this are not known — it may be that Omicron is good at evading existing vaccines but less virulent, or there may be other factors at work.
Health experts and scientists explicitly point out that not enough information is currently available about the variant to accurately predict its impact on a larger scale, so the virus must be dealt with carefully.
According to some projections, in the worst-case scenario, Omicron could infect 500,000 people a day, leading to 3,875 daily deaths in the US alone. Some modelers in the UK have projected that Omicron could lead to as many as 2 million daily infections in that country by January.
As of December 19, only around 10,000 cases had been identified in the UK, but the number of actual cases in the UK is expected to be much higher than that as those who have only mild symptoms may only be testing at home, and reporting their results, and home test kits do not distinguish between Omicron and Delta.
"We need to prepare for the worst and hope for the best,"
Alessandro Vespignani, Computational epidemiologist, Northeastern University
The first UK death due to Omicron was also reported in the UK on December 13, 2021, after which British prime minister Boris Johnson warned the citizens that it is possible the new variant could even evade the immune response developed in the human body after two vaccine shots. In order to prevent Omicron from overwhelming the UK health services, the British government has employed a nationwide booster dose program that aims to give everyone eligible a booster shot by the end of the year.
What makes Omicron so effective is the large number of mutations found on its spike proteins. Omicron is thought to have about 50 genetic mutations, with around 36 in the spike protein — that is the part that lets the virus attach to human cells and work its way inside. Some of the mutations make the virus’s connection to the cell stronger, allowing it to spread more easily.
Antibodies may also find it more difficult to attach to the vastly different Omicron spike, helping the virus to evade immunity and making the antibodies less effective at stopping the virus from infecting new cells.
What is our best hope against Omicron?
According to Dr. Anthony Fauci, who is the Chief Medical Advisor to the US president, Omicron has definitely affected the protection that is provided by two-dose vaccinations of Pfizer and BioNTech against coronavirus transmission, but it has not reduced the ability of these vaccines to prevent severe illness in fully vaccinated patients. Fauci has also pointed out that, “a booster dose increases protection against symptomatic disease to 75%”. He further claims that “at this point, there is no need for a variant-specific booster. Instead, all Americans who are eligible for primary vaccination and booster doses should get them as soon as possible”.
Researchers at Imperial College London have analyzed the likely impact that a COVID booster shot will have on Omicron and say it could provide around 85% protection against severe illness. They suggest that this will keep many people out of the hospital.
Apart from vaccination, the Centers for Disease Control and Prevention (CDC) also encourages the use of face masks and social distancing. The CDC website mentions that masks can restrict the spread of all coronavirus variants in public settings.
On the other side, health experts believe that while the Omicron strain is not more dangerous for the fully vaccinated, and may even be slightly less dangerous, it is just as dangerous as Delta for those who are not vaccinated. In fact, because of its high levels of transmissibility, Omicron may make it more likely that the non-vaccinated will become infected, and this will translate into greater numbers becoming seriously ill.
Jeff Zients, who is the COVID Response coordinator at White House told CNBC in an interview that the risk of death in case of unvaccinated COVID patients is 14 times higher as compared to those who have received their double dose of vaccine.
WHO reports also confirm that vaccination reduces the risk of serious illness in patients infected with the Omicron variant.
Today (Dec 20), Moderna announced that a booster shot of its vaccine (50 μg, as opposed to 100 μg for regular shots) was found to increase the level of antibodies by about 37-fold. The trials were run solely on lab testing data, so it's hard to tell if this would be enough to prevent infections in the real world. Although, it's safe to assume that a booster shot would drastically reduce hospitalizations.
The trial also tested the viability of 100 μg doses as booster shots, although the authorized dosage for a booster shot is 50 μg. While this produced an 87-fold increase in antibodies, it also spelled more side effects compared to a 50 μg shot.
What else do we know about the Omicron variant?
Marc Veldhoen, who works as an immunologist at the University of Lisbon, explains that unlike Delta and previous other strains of coronavirus, the Omicron variant does not primarily attack, the lungs but instead prefers to stay and multiply in the respiratory tract. This could also be the reason why it is less virulent in most vaccinated patients. With every passing day, more such aspects and impact of the Omicron variant are coming forward:
- Scientists have recently come across a “stealth Omicron variant” BA.2/B.1.1.529.2. BA.2 which may be harder to track using existing standard PCR tests because it lacks a particular mutation found in normal Omicron variant BA.1/B.1.1.529.1. The stealth variant has many mutations in common with standard Omicron, but it lacks a particular genetic change that allows standard lab-based PCR tests to be used to identify probable cases. The stealth variant was discovered in coronavirus samples collected from Australia, Africa, and Canada. Some countries, such as Denmark, use a special PCR test to diagnose Omicron patients.
- The EU has recently decided to place an order of 180 million doses of Pfizer vaccine adapted to fight Omicron. On December 16, European Commission head Ursula von der Leyen released a statement confirming the decision — "Member states have agreed to trigger the first tranche of over 180 million extra doses of adapted vaccines, in our third contract with BioNTech Group and Pfizer".
- According to an estimate, the number of Omicron infections may double every two days. Due to the increasing spread of Omicron, lockdowns are also returning in many places leading to protests and a state of uncertainty.
- To keep an eye on the activity of coronavirus variants like Omicron in the US, the CDC uses a National SARS-CoV-2 Strain Surveillance (NS3) System. This system involves public health laboratories shipping anonymized specimens to the CDC to provide a representative set of viruses for sequencing.
Despite the rapid progress being made against Omicron, more than 40% of the world's population remains unvaccinated, or only partially vaccinated, meaning that the emergence of new variants like Omicron may continue to be a major threat.
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