This article is about the variant of SARS-CoV-2 newly discovered in Botswana on November 9, 2021. On November 26, the WHO officially named it Omicron and classified it as a VOC (variant of concern).
Resistance of the Omicron variant
Of the mutations discovered so far, it is likely to be the most drug-resistant. It is estimated to have a minimum of five-fold mutation and a maximum of nine-fold mutation. According to the research results of the Ministry of Health of South Africa, 58 RNA blueprints were different from the existing ones, and 32 mutations occurred in the spike protein. The variable is how much more mutation will occur.
Vaccines against Omicron variant
First, there is a problem that 19 parts of the vaccine neutralizing antibody design were mutated. These parts are not only utilized for the virus to penetrate cells, but also are involved in increasing the transmission power and fatality rate. An analysis suggests that the virus may have evolved in a direction to evade immune function due to the expansion of vaccination.
Therefore, it is difficult to expect the same efficacy as before even if booster shot is implemented with the current generation of vaccines made based on the initial subtype. To effectively counteract this mutation, a mutagenic vaccine based on a close ancestor of the Omicron variant must be readily available. Fortunately, with the advent of the mRNA method, it is expected that an Omicron-specific vaccine will be developed within a few months and clinical testing will be possible.
Even if Omicron variant limits the antibody immunity effect of the vaccine, it is assumed that it will not completely negate the cellular immunity effect provided by the vaccine. However, in the case of the elderly or chronically ill, cellular immunity is somewhat lower, so additional vaccination with the current-generation vaccine is insufficient to induce cross-immunity between the antibody and the immune system. The only solution is to receive a booster dose of the next-generation vaccine, which will be modeled on the micron mutation.
AstraZeneca has already been studying Omicron variant-related strains in Africa for several months, and Moderna has verified the effectiveness of the vaccine within a few weeks and confirmed the next best solution to increase the dose during vaccination. Ancha Baranova, a professor of systems biology at George Mason University in Virginia, said in an interview that viral vector vaccines such as Sputnik V would be effective against micron mutations because viral vector vaccines show a broader effect on strains than mRNA vaccines. “In two weeks, Pfizer, USA, will be testing a way to neutralize a strain of Omicron and presenting how Omicron interacts with antibodies,” she said in an interview on Nov. 29. The Russian RDIF announced that Sputnik V was effective against Omicron variants, but Russian government officials said there were no data yet on whether Sputnik V was effective against Omicron variants.
Treatment for Omicron variant
Most antibody therapeutics such as Regeneron are designed to target the spike protein, increasing the possibility that the therapeutic efficacy will be lowered due to concerns about resistance.
However, antiviral agents such as Paxrovid and Lagebrio are expected to preserve their effectiveness to some extent because they target the replication mechanism rather than the spike protein.
Pfizer announced that its COVID-19 antiviral drug, Paxrovid, was prepared in preparation for the variant, and that it will also be effective against the Omicron variant.
Risks of Omicron variant
There are 77 confirmed cases of Omicron variant in South Africa, but there is also a study result that over 90% of mutation detections overtook the delta mutation and have already become the dominant species. Fortunately, the number of confirmed cases in South Africa is smaller than during the third wave of delta mutations. However, there are signs of widespread spread of the infection, and a fourth wave may occur.
Dr. Angelique Kuche, president of the South African Medical Association, who first reported the Omicron variant, cautioned, “The symptoms are unusual but mild, but the effect on the elderly needs to be investigated.” In the case of South Africa, 65% of Omicron variant confirmed patients were unvaccinated, and many hospitalized patients were also identified as unvaccinated.
Since the spike protein mutation affecting the propagation power is about twice that of the delta mutation, there is an opinion that the propagation power will surpass even the delta mutation. The danger is proving to be due to the rapid outbreak of secondary infection without close contact in Hong Kong. Patient 2 in Hong Kong seems to have been infected with Patient 1 or another common source of infection because the virus and genome analysis of Patient 1 match. The problem is that Patient 2 has no travel history to Africa and has no close contact with Patient 1. As a result of an epidemiological investigation, the Hong Kong authorities are presuming that Patient No. 1 was able to go out with the virus in it by wearing a valve-type mask. The authorities urgently quarantined 12 people in the rooms around patients 1 and 2 at the hospital. Fortunately, among the 12 people, no additional confirmed cases were identified until November 27.
There are opinions that the transmission power will be weak because the virus is unstable due to too much mutation, but from the cases so far, the contagiousness does not seem low. Due to the lack of data yet, it is uncertain whether it will surpass the contagiousness of the delta mutation that is currently prevalent worldwide. The lambda mutation also spread rapidly in South America, and there were some countries where it became the dominant species, so there was an opinion that it surpassed the contagiousness of the delta mutation, but in the end, it failed. In other words, the Omicron variant is also highly contagious, but whether it will be stronger than the delta mutation remains to be seen. There is also a study result showing that it has 6 times more contagiousness than the existing wild species and twice as much as the delta mutation.
The progress so far cannot be judged because of the small sample size, but there are also claims that the result of COVID-19 mutation is the Omicron variant based on ‘higher contagiousness, lower risk’, which is the standard of virus mutation. If this prospect is true, the Omicron variant only has high infectivity, and the risk itself can be evaluated low. However, caution is still needed as a ‘low risk’ may lead to carelessness in quarantine, which may actually cause a higher lethality to patients with underlying diseases and the elderly.
Countries’ response to the Omicron variant
- The Philippines, Hong Kong, Japan, Canada, the United States, the Middle East and European countries have placed South African countries on travel bans.
- The Republic of Korea has decided to take measures to ban entry of foreigners from eight countries, including South Africa.
- The state of New York has declared a state of emergency in case of a possible spread of the Omicron variant.
- As of 0:00 on November 30, 2021, the Japanese government announced a ban on new entry of all foreigners, including short-term stays for business purposes, international students, and technical trainees, and effectively closed the border.
- The Israeli and Australian governments, like Japan, have announced a ban on new entry for all foreigners, effectively closing their borders.
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