Covid, Christmas, new variants and vaccines

Just when I thought I was getting on top of the rules, with a Covid-compatible Christmas gift-wrapped and ready to go, everything mutated, including the new coronavirus itself. Five days of festivities became one, and, sadly, my mother-in-law couldn’t come to stay. Needless to say, I’m devastated...

What provoked this abrupt change of policy is the dramatic uptick in detections of a new variant of the coronavirus that was first picked up back in September. As a world leader in genomics, the UK has a dedicated consortium, called COG-UK, on the prowl for covid mutants. They’ve read through the genetic codes of tens of thousands of viral samples collected from patients across the country, and this new variant was a new blip on their radar.

Called VUI-202012/01, the new variant contains a constellation of 17 genetic changes. These are peppered throughout the viral genome, but many are concentrated in the region that codes for the the “spike” protein that forms the outer coat of the virus. The spike is the critical component used by the virus to latch onto and invade our cells.

Changes here have important implications. If the spike changes significantly, the virus might not be recognised by the immune response provoked by vaccination. At the moment, thankfully, scientists don’t think things have gone that far, but many regard this as a stepping stone to a future variant that does have this ability. This means that surveillance is critical so we can keep a searchlight trained on the virus and anticipate when it’s about to make its move.

But regardless of whether it can enable it to side-step a vaccine, changes in the spike can also alter the infectivity of the virus, making it much more efficient at grabbing hold of our cells and forcing entry. The result can be a more transmissible virus, and this is what researchers believe is happening right now.

Initially, the variant accounted for only a small proportion of newly-diagnosed UK coronavirus cases. In fact, researchers speculate that it might have evolved in the first place in a patient with a weakened immune system. This would have allowed the virus to grow partially unchecked for a while, providing it with the opportunity to mutate into its present form.

By November it was accounting for 25% of cases in some parts of the country, and by mid-December it was over 60%. This suggests that the new variant is out-competing the original coronavirus strain, a bit like a best seller in a bookstore.

Detections of the new variant map onto regions of the country – the east, southeast and parts of London – where covid diagnosis rates are growing the most rapidly, even defying the effects of lockdowns and hefty restrictions on people movement, mixing and hospitality. This points to a virus better optimised to spread, although without any apparent increase in severity when it infects.

With the risk of accelerating the pace of the pandemic across the UK, the government reined-in Christmas and plunged millions of people into hardcore “stay at home” restrictions intended to buy time while the vaccine roll-out scales up.

说到这里,到目前为止有一百万英国人甲型肝炎e had their first dose of Pfizer’s vaccine. The UK was the first western country to approve the jab, which was also licensed by the European Medicines Agency (EMA) last week, and two more vaccine candidates wait in the wings for regulatory approval. One outlet reported recently that AstraZeneca’s vaccine is expected to be approved by the UK’s MHRA at the end of the month, and Moderna’s agent was given the nod last week by the FDA in America, which is likely to help speed things along.

In the UK, two healthcare workers – who recovered uneventfully – developed allergic reactions to the Pfizer vaccine, prompting the regulator to advise anyone with a track record of severe allergy to forgo vaccination. Otherwise the roll-out has been uneventful and the agent is well-tolerated.

Nevertheless, half a million people in the UK is still a drop in the ocean. In the country as a whole over 50 million will need vaccinating, and globally close to 8 billion. Even if the UK does achieve a vaccination rate of 1 million people per week, it’ll still take a year to get to everyone. And what none of the vaccine-makers can say for sure yet is how future proof their vaccines are: for how long will the immunity they provide last? Have we created the immunological equivalent of the Forth Bridge that needs repainting before you’ve even finished the job the first time? And are the reassuring noises issuing from politicians – that the new covid variant won’t affect vaccine performance – reliable? The experiments, we’re told, are taking place, but we’ll have to wait a few weeks to find out...