Scientists believe that the Omicron Covid variant is less deadly than other versions of the virus because it is more likely to spread to the throat. Omicron does not damage people's lungs as much as previous versions of Covid, according to six studies published since Christmas Eve. The studies have yet to be reviewed by other scientists.
The professor of virology at University College London said that Omicron may have changed its ability to cause infections.
It looks to be able to get to the cells in the throat. It would be easier to spread in cells there than in cells deep in the lung. The studies point in the same direction.
The rapid spread of Omicron could be explained by the fact that the virus produces more cells in the throat. A virus that is good at infecting lung tissue will be more dangerous but less transmissible.
Prof James Stewart said that a pre-print was published on Boxing Day showing that Omicron leads to less severe disease in mice. The paper shows that Omicron causes mice to lose weight, have lower viral loads and experience less- severe pneumonia.
He said it was one piece of the jigsaw. The animal model suggests that the disease is less severe than Delta. It seems to get cleared faster and the animals recover more quickly.
The early indications are that it is good news, but that is not a signal to drop our guard because there are deaths from Omicron. Not everyone is able to party with their masks off.
The Syrian hamsters had a lower viral load in their lungs than other hamsters. The professor said that it could be because the virus was better at infecting humans than hamsters, or that it was more likely to cause less severe disease.
Some research suggests that the throat is more likely to detect Omicron than the nose. There is a photograph of Huw Evans/Rex.
A pre-print submitted to Nature last week by researchers in the US found that mice with Omicron lost less weight and had a lower viral load. Omicron has changed the way it enters the body according to researchers at the University of Glasgow. Omicron was likely to evade the immunity of people who had had two doses of the vaccine, but a booster dose gave a partial restoration of immunity.
A study from the University of Hong Kong last month showed less Omicron infections in the lungs, and a research team at the University of Cambridge looked at blood samples from vaccine patients. Omicron was able to evade vaccines, but not enter lung cells.
There is a debate about how best to carry out home-testing. Some scientists suggested last week that the tests might be more accurate if people took saliva from the throat and nose. The professor at University College London said that she had tested positive for LFTs when she took a sample from her throat.
A study from South Africa showed that saliva samples were better at detecting Omicron than nasal samples.
The study was not significant enough for conclusions to be drawn, according to Prof Lawrence Young. This is a small study on patients who are not in a hospital. It confirms that salivary testing could be useful as a sampling approach. I don't think this study is significant enough to conclude anything about the behavior of Omicron.
The UK Health Security Agency said there was no evidence that rapid tests differed in their ability to detect the Omicron or Delta variant. The devices used by the test and trace are proven to be highly effective at detecting Covid-19 in people. There are a lot of positive tests reported. We are detecting tens of thousands of cases that might have gone undetected.
