IT is almost a year to the day since the UK's Covid vaccination drive launched on December 8 when Margaret Keenan, a 90-year-old grandmother in Coventry, became the first person in the world to be immunised outside of a clinical trial.

Within weeks it became clear that a highly transmissible new variant later dubbed Alpha, which had spread from Kent, would slow the return to normality and cause thousands of extra Covid deaths in the process during a devastating winter wave.

HeraldScotland: Confirmed Covid cases have been falling in Scotland since mid-November Confirmed Covid cases have been falling in Scotland since mid-November

Twelve months later, many scientists believed the virus had evolved into its 'peak' form with the subsequent rise of Delta, a strain which crushed and outcompeted all others wherever it took hold.

Now, having amassed half a Greek alphabet of variants already, the world is faced with a new unknown: Omicron.

READ MORE: Omicron 'most challenging' development in months, warns Sturgeon

Like the first 'variant of concern' Alpha, it shares a marker - the S-gene dropout - which enables potential cases to be detected quickly in PCR testing before being confirmed through genomic sequencing.

Surveillance indicates that these 'S-drop' cases began rising from November 16, though not all were Omicron. Those that are, are concentrated in Lanarkshire and Greater Glasgow and Clyde.

Could COP26 have seeded the new variant into the west of Scotland? The first know case of Omicron was detected in Botswana in a specimen collected on November 9 - three days before the summit ended - but the variant had almost certainly been spreading in Africa for weeks.

So far contact tracing has found no link.

However, there is evidence of community transmission - described as "limited" at this stage - since at least some of Scotland's confirmed cases cannot be traced to travel.

For now, governments at Holyrood and Westminster are steering clear of the curfews, hospitality closures, and circuit breakers that characterised the battle with Alpha.

READ MORE: 'A dramatic change from everything we have seen': Why the new Covid variant has scientists scared 

Vaccines may not have put an end to Covid as we wished, but immunity is still much higher than it was and boosters - not lockdown - will be the first line of defence, bolstered by surveillance and sequencing to find cases, tougher rules on travel (hotel quarantine for red list countries and PCR testing for all arrivals), and 10 days of self-isolation for anyone identified as a close contact of someone infected with Omicron - even if fully vaccinated.

Whether this will be enough depends on a lot of unknowns: its transmissibility; whether and how well it can escape vaccines; whether it causes more severe disease; and to what extent Omicron has already spread in the UK.

It also depends on us: is the public willing to "step up" compliance enough, or has apathy set in?

Whatever the answers, we will probably know them by Christmas.