As growing evidence points towards large numbers of people becoming infected with Omicron across the globe, there are additional concerns that Omicron is just the starting point for more variants to emerge - potentially maintaining its high levels of transmissibility but with maybe greater virulence. Of most concern is that, as new variants like Omicron appear, there is a broadening of the groups at risk of serious disease after infection.
Each new variant deriving from Omicron could challenge the efficacy of any cumulative, existing immunity to infection we have obtained from vaccines or previous infections, slowing down how quickly we can emerge from the pandemic.
A worrying possibility is whether the profile of the groups at risk from infection were to change. For instance, children are relatively spared from severe disease after infection with other variants, and hopefully this remains the case with the Omicron variant. Nevertheless, if the susceptibility of young children were to change, then it would alter how we approach the control of SARS-CoV-2 infections. The key point is that, just because the virus has followed a particular pattern before, it does not mean this will be followed in the same way in the future.
Early assessments suggest that antibodies induced after vaccination give quite either no, or quite modest protection against infection. Most likely, because of T cells, there will be better protection by vaccines against the most serious presentations of COVID-19, but these are early days in our understanding of this. Boosters most likely will enhance this protection, irrespective of whatever vaccine was given before, and really importantly, the benefit from boosting is likely to occur really quickly, within a few days of receiving the additional boost. It is likely that those who have been vaccinated and previously infected will have the best protection against Omicron, and it would be reasonable to think that a vaccine boost would help temper the spread and severity of infection with the Omicron variant.
The appearance of new variants is not unexpected. What has been surprising has been the speed of appearance of Omicron and the sheer number of mutations observed in this virus. One possibility is that the variant emerged from an individual who was immunocompromised in one way or another and this individual acted as an incubator allowing the variant to develop over time. Another possibility, is that people with normal immune systems can maintain the virus for longer than we originally thought, or that it came from another source. If it did come from an immunocompromised patient then this would be especially concerning as it means such variants can emerge at multiple and near-random times in the future. That said, if infections with Omicron turn out to be less severe, and it’s a big if, then maybe evolving within an individual could help explain this.
The overarching point is that the longer the pandemic continues, the longer infection rates are maintained at high levels, aided by low levels of vaccination and the limited use of other control measures, then the more likely that the groups at risk of severe disease may alter too. There are millions of new infections each month, which of course means we are more likely to see new variants emerging, each one challenging our ability to control these infections. Omicron shows why it is vital to vaccinate people, not just in the UK, but worldwide, as this virus does not respect borders.