How dangerous is Omicron contamination? To date, evidence suggests that this infection is generally mild and may damage the lungs less than Delta and the original Wuhan strain.
Omicron is less effective at infecting cells deep in the lungs, which can lead to serious illness, according to a Cambridge University study. “Reports from South Africa show that the Omicron variant had surprisingly few serious diseases for the number of reported cases,” says Andrew Preston, professor of microbial pathogenesis at the University of Bath.
However, the expert adds: “We must be careful about extrapolating this experience to the UK because our population profile is very different. The UK was relatively hard hit in the first wave, which indicates that our population is more prone to serious illness. Immunity levels also differ between the two populations, and other infectious diseases that people in South Africa and the UK face during their lifetime also differ, and this may affect their response to specific infections. ”
Ultimately, the severity of COVID depends on a number of factors, including underlying medical conditions such as type 2 diabetes, says Will Irving, professor of virology at the University of Nottingham. the immune system, and on the size of the infecting dose ”- in other words, on how many viral particles a person inhales.
“The advantage of getting vaccinated,” says the specialist, “is that it speeds up the body’s response and increases the likelihood that the immune system will win the race before serious illness develops.”
Why are there such different symptoms in a disease? According to Professor Preston, the evidence so far suggests that Omicron’s symptoms are more similar to those of the common cold (runny nose, headache, weak or severe fatigue – sneezing and sore throat) rather than the classic COVID symptoms such as loss of taste. and smell. …
“This could be due to the fact that Omicron has a number of mutations that distinguish it from previous versions,” he adds. “For example, Omicron has 50 mutations, including 32 in the S gene, which encodes a spike protein in the virus that allows it to access our cells. This compares with 13 mutations in the S gene with Delta. Perhaps some of these mutations alter its interaction with our body, and this changes the nature of the symptoms caused by infection with Omicron. “
Another factor, in his opinion, is that “a higher level of immunity” in the population can change the way Omicron interacts with our body, “limiting the amount of accumulated virus or tissues that the virus reaches.
More respiratory viruses such as colds and flu are also circulating this year, and this could also change the pattern of symptoms as they can stimulate the general immune response in the body, causing symptoms such as fever, which is designed to slow down the multiplication of pathogens. ”
Another question asked by the Daily Mail is why is Omicron so contagious?
“Omicron’s mutations improve its ability to infect the body,” says Professor Preston. “There is some evidence that it is able to bind more tightly to the ACE2 receptor, making it easier to infect our cells.” ACE2 receptors are proteins found on the surface of many types of cells and the pathways by which the virus infects them.
“In addition, Omicron is more capable of avoiding immunity from vaccination or previous infection, so it is able to infect people, which other options cannot,” the expert says.
But there are also pluses. Omicron is spreading fast because it only takes a small amount of the virus to infect, says Tim Spector, professor of genetic epidemiology at King’s College London, who runs the ZOE Covid virus tracking application. – Symptoms appear more quickly – two days after exposure – and seem to last less time. This is not ideal for a virus as people shed less virus in less time and are less likely to transmit it unintentionally. ”
Can a person first become infected with the Delta coronavirus, and then the Omicron variant?
“In short, yes,” says Professor Preston. “Omicron, in particular, appears to be able to overcome the protection provided by both prior infection with another COVID variant, such as Delta, and prior vaccination. This is not unusual: Delta was able to evade to some extent the immunity stimulated by the Alpha variant. The good news is that almost certainly any symptoms will be milder than if you had not been previously infected or vaccinated. “
If a person is vaccinated, is he at risk of contracting Omicron?
Two doses of COVID vaccine provide much less protection against the new Omicron variant than against Delta, the Daily Mail writes. Initial data show that 25 weeks after the second injection, the Omicron protection rate ranges from 10 to 40 percent, depending on which injection was given, according to analysis by the UK Health Safety Agency (UKHSA) earlier this month. Two doses of the AstraZeneca vaccine provided 40 percent protection against symptomatic Delta infection and possibly less than 10 percent against Omicron. For the two Pfizer shots, the rates were 60% and less than 40%, respectively.
Similar results were found in a study published by Columbia University in the United States last week, which found Omicron was “markedly more resistant” to all four COVID vaccines used in the United States.
Dr. Susan Hopkins, the UKHSA’s chief medical adviser, says: “I think we can see that if you took two doses more than three months ago, it won’t stop you from getting symptomatic illness.”
However, the same analysis showed that booster vaccination increased protection by more than 70 percent. This was corroborated by Imperial College data released last week, which suggests that two weeks after the second dose of vaccine, protection against Omicron is between 0 and 20 percent; but after revaccination this figure rises to 55–80 percent.
One reason for this is that while boosters are not specifically designed for the Omicron variant, they cause the body to produce more antibodies. Antibodies are proteins made by the immune system when it is threatened by insects and viruses.
And studies have shown that counts of antibodies against SARS-CoV-2 (the virus that causes COVID) are taken into account, even if they are not relevant to this option.
Other studies show that killer T cells, which are also activated by the vaccine, retain much of their ability to target the virus, even when it is a new variant.
“We still expect two doses of the vaccine to dramatically reduce the risk of serious Omicron disease compared to unvaccinated people, but it is clear that boosters provide significantly more protection against disease,” says Professor Preston.
Is an unvaccinated person more likely to pass on the Omicron to other people? “In short, yes,” says Professor Will Irving. “Getting vaccinated or having COVID provides some degree of protection so you can still get infected — but it will help limit the replication of the virus in your body and reduce your viral load.” This may not be enough to prevent vaccinated people from infecting others. But they are likely to be less contagious because they will carry less virus in their body and for shorter periods of time. ”
When will the Omicron wave peak? Professor Chris Whitty, England’s chief physician, predicted last week that the Omicron wave would “peak rather quickly” and then disappear earlier than previous options.
Professor Preston explains why this can happen: “Infection accumulation is a combination of the infectiousness of the virus and the susceptibility of the population it infects. Omicron infections are on the rise because this option is super infectious, and two doses of the vaccine do not provide good protection against it, so many people are susceptible to infection. “
The plus is that after a rapid infection of a large number of people, these people will develop some immunity, and the circle of people who remain susceptible to Omicron will become smaller and smaller.
“When this happens, the infection rate will begin to decline, hopefully quickly,” the expert says. – Thus, the faster the virus exhausts the circle of susceptible people, the sooner the rate of infection will begin to decrease. The number of people getting a raise every day is also likely to reduce the number of susceptible people. ”
Changes in behavior – wearing masks, canceling parties, and working from home – will also help slow the spread of infections, Prof Spector said. “These changes will slow the spread of the virus, but in the new year, the number of cases could peak higher than anything we’ve ever seen,” he says.
How accurate are the tests in the case of Omicron? It has been suggested that lateral flow tests (LFTs) do not detect this variation – this is not the case because viral proteins still bind to the antibodies used in the test. In terms of PCR, “a series of PCR tests target three different regions of the viral genome to determine if a virus is present or not — each test includes three separate results, providing excellent reliability,” says Professor Preston. “Genome sequencing is required for definitive proof of Omicron infection, but it will take a week. PCR data is invaluable while infections are growing so rapidly. “
“If there are a lot of colds around and more people have mucous noses, it could compromise the quality of the sidestream nasal swab,” adds Professor Preston. “Likewise, if Omicron itself causes a runny nose, it can have a similar effect. However, PCR tests require cleaning the throat and nose with the same swab, so this is unlikely to affect the PCR results. ”
See also: “The doctor named the most common symptoms of the omicron-strain of coronavirus”
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