Analysis: scientists are only starting to understand new Covid mutation but there is encouraging news from the laboratory, South Africa and on antiviral drugs
Last modified on Tue 21 Dec 2021 22.11 EST
It’s hard to find much good news among the waves of grim statistics that have washed over the nation since the emergence of Omicron.
Once again, the NHS is threatened and again, the prospect of a new year lockdown looms. We seem to have gained nothing in the battle against Covid-19 during the past 12 months.
Such an interpretation is harsh, however. Yes, we are again facing a serious medical crisis, but a number of factors suggest there may be some ground for a little optimism, though scientists are careful to add the key caveat that we are only at the beginning of our dealings with the Omicron variant.
Over the past year, a number of anti-viral drugs, such as Xevudy (sotrovimab) and Lagevrio (molnupiravir), have been shown to ward off serious illness and have been earmarked in the UK for vulnerable people – those being treated for cancer, for example – who subsequently become ill with Covid-19. Both drugs reduce the amount of virus produced in the body after infection and lessen the chance that patients will need hospital treatment.
“Those most at risk, such as cancer patients, are the most likely to need health service care, so with this new, highly infectious strain, these drugs should help reduce the burden of Covid-19 on that population and have a knock-on effect on the health service as well,” said Professor Penny Ward of King’s College, London. “On top of booster vaccines, these drugs will provide important additional protection for those who are most at risk.”
Omicron was first pinpointed in South Africa, which then experienced a very rapid rise in numbers of Covid-19 cases. But now these case numbers appear to have peaked, while early indications also suggest that deaths could be lower than they have been for previous waves. Thus, the country is experiencing a relatively brief wave of milder infections. Health officials have also reported that people appear to recover more quickly from Omicron compared with Delta, whether they were in hospital or not.
It remains to be seen whether these figures mean Omicron produces milder illness than previous variants in other countries, including the UK. Nevertheless it remains a possibility with some scientists expressing quiet optimism, though others are more cautious.
“In South Africa, they had a very large wave of Delta only a few months ago, so they are likely to have a fair amount of immunity lingering in the population and that could be providing protection,” said Lance Turtle, senior clinical lecturer in infectious diseases at Liverpool University. “In the UK, our protection might have begun to weaken, so we might see more serious cases.”
This point was also made by the government’s scientific advisers, Sage. “Even if there were to be a modest reduction in severity compared to Delta, very high numbers of infections would still lead to significant pressure on hospitals,” it noted in minutes for its meeting last Thursday.
However, Professor Martin Hibberd, of the London School of Hygiene & Tropical Medicine, was still optimistic. “We are in a better position than a year ago, as most people have now had at least some vaccine, or previous infection, which may help to reduce the severity experienced by many people.”
A third piece of hopeful news is that scientists have uncovered a possible biological explanation for Omicron’s apparent reduced severity. This work was carried out by Michael Chan Chi-wai at the University of Hong Kong who found that although the new variant is much more efficient, compared with Delta, in reproducing in the upper respiratory tract, where it can be coughed out onto others, it is far less efficient in spreading in the lungs where it would pose the greatest danger to an infected person.
In this way, the variant may spread between individuals far more quickly but not reach more vulnerable parts of their anatomies. This would reduce the severity of illness it can trigger.
However, Chan has counselled caution in interpreting the implications of his work. “By infecting many more people, a very infectious virus may cause more severe disease and death, even though the virus itself may be less pathogenic,” he said. “The overall threat from Omicron variant is likely to be very significant.”