Coronavirus: Scotland's exit from lockdown hinges on vaccines, variants, and supplies

In Scotland, we are working towards April 26 as a date when hotels, restaurants, pubs, hairdressers, and retail can reopen to customers for the first time since December.

But it is unclear exactly what form this will take after talk of ‘Level Three’ restrictions were swiftly replaced by the suggestion that parts of the country could be fast-tracked straight into ‘Level Two’ instead if their virus rates low enough, and then clarification that the levels themselves are being revised.

READ MORE: Scotland will vaccinate under-50s by age, not occupation

This might mean an end to curfews or alcohol bans limiting how hospitality can operate, reinterpretations of the ‘Rule of Six’ for socialising, and allowing friends and family to mix in one another’s homes earlier (rather than waiting for Level One).

The UK has one of the fastest vaccine rollouts in the world, but is far behind Israel where over 90% of the population has had at least one Pfizer dose to date

At the same time, England has set a more ambitious timeline (subject to four-weekly data reviews) potentially allowing a resumption international travel after May 17 and a return to something “broadly normal” from June 21, when limits on social contacts would be lifted and nightclubs allowed to reopen for the first time in 15 months.

Nicola Sturgeon has stressed that Scotland’s exit from lockdown could progress “further and faster” if the evidence allows. So what might enable us to speed up - and what could still slow us down?

The Covid vaccination programme puts the UK as a whole at a major advantage.

READ MORE: Parts of Scotland 'could go straight into Level Two' in April

To date, more than 18.7 million people in the UK - 28 per cent of the population - have received a first dose inoculation.

This is mirrored in Scotland, where more than 1.5 million have been immunised since December 8, including nearly 57,000 who have now had second vaccine doses.

Uptake in Scotland in the priority age groups has been extraordinarily high at 100% for elderly care home residents, over 80s and the 75-79-year-olds in the community, 98% for 70-74-year-olds, and 94% so far for the 65-69-year-olds.

As immunisations are rolled out to the under-50s uptake may fall, but even if it averages 85% across the adult population (research is ongoing about whether to include children), protection against death and hospitalisation would still be high based on growing real-world evidence for the vaccines.

For example, if a vaccine is 90% effective at preventing serious disease (a Public Health Scotland study this week put the figure at 85% for Pfizer/BioNTech and 94% for Oxford/AstraZeneca, based on hospitalisations) and uptake is 85%, then 77% of the population are shielded from becoming sick.

READ MORE: Israel shows Pfizer vaccine 96% effective at preventing disease after second dose

Some younger, healthy people might choose not to be vaccinated - either because their individual risk is low or they are suspicious of the vaccine - but unvaccinated people can still transmit the virus, potentially endangering those with weakened immune systems who either cannot be vaccinated or do not respond strongly to it.

In Israel, young people have been incentivised with beer and pizza to get their jags, while a "green pass" vaccine passport system is also being used to determine access to public and leisure facilities such as gyms and cinemas.

Residents of Tel Aviv have been encouraged to attend vaccination centres by offers of free beer and pizzas

Besides high uptake and a sharp reduction hospitalisations and deaths, we would also want to see evidence that vaccination is cutting transmission.

Increasingly, we are.

A study by Addenbrooke’s Hospital in Cambridge, published yesterday, found that vaccinated healthcare workers were four times less likely than unvaccinated colleagues to test positive for Covid 12 days or more post-vaccination.

If people are not infected, they cannot pass the virus on.

On this basis, the faster we roll out vaccination, the faster we will slow and stop transmission, and reach the goal of herd immunity.

Death have been falling fastest among the oldest Scots, who were prioritised for vaccination

However, roughly 80% of Scotland’s population is under 65 which means that, were we to lift restrictions in the near future, there remains a substantial pool of potential transmission which would give the virus ample opportunity to mutate into forms which might evade vaccines.

It is unclear exactly what proportion of the population is naturally immune due to prior infection, but antibody surveillance suggests it is no more than around 10%.

As Rupert Beale, an immunologist and group leader at the Francis Crick Institute’s infection laboratory, put it this week: “The biggest risk to the success of the vaccination programme is easing restrictions too early.”

The speed of the vaccine rollout in the UK has slowed during February. Issues with supply have been blamed

There are other unknowns. For example, interruptions to supply.

Scotland’s vaccination rate has halved since mid-February, and the UK is currently dependent on just two suppliers - AstraZeneca and Pfizer - although deliveries of the Moderna vaccine from the US are expected from late March.

There have also been some concerns about how quickly the new ‘Kent’ strain of the virus could take off if restrictions were lifted too quickly.

The variant is now accounting for at least 85% of cases in Scotland and is also estimated to be up to 70% more transmissible than the original Wuhan strain as well as up to 70% deadlier.

This could make it much harder to keep the R number below one as restrictions are eased, and put intensive care under pressure.

The daily average number of cases in Scotland has shown signs of plateauing since mid-February

Already we are seeing evidence in Scotland that cases are plateauing now instead of falling, and nearly two thirds of the standard ICU bed quota continues to be occupied by someone diagnosed with Covid. These patients are also younger - 61 on average - which means the effect of vaccination is seen later.

Israel, whose coronavirus cases are also dominated by the ‘Kent’ variant, waited until more than 60% of its population had at least one vaccine dose before easing its lockdown, but has only accelerated that process to include opening shops, bars, restaurants, gyms, swimming pools, and hotels this week once single dose coverage reached 85%. 

The UK would not reach that threshold until everyone aged 20 or older has been inoculated, some time in June.

'Modelling the epidemic in Scotland' (Source: Scottish Government)

Right now, however, Scotland is in a better position than we expected to be. Occupancy of both ICU and overall hospital beds is lower even than the best case scenario modelled by Scottish Government experts.

The next few weeks will determine whether we exit sooner, or later.