Has the Prime Minister made himself a hostage to fortune? At the coronavirus press conference on 22 February, he said emphatically that “we are now travelling on a one-way road to freedom” and “we will not go back”.
Last time the Prime Minister referred to freedom it was to shift the blame of the high number of Covid-19 deaths. He said that stricter control measures could not be implemented because “our country is a freedom-loving country.”
I am looking forward to most restrictions being lifted and to summer holidays. However, we need to be smarter than in the previous lockdowns exits. Baselines measures, such as safe schools, facemasks and test and trace need to continue and be improved.
It is good to have a roadmap, but is it wise to have dates if we are really going be guided by “data not dates”? Now that dates have been announced, there will be a formidable resistance to change them, regardless of the data.
How can we be sure that we can lift most or all restrictions by 21 June, as announced? The current vaccination process will only be completed in September, as two doses are required for optimal protection.
Ideally, we would lift all control measures only when we have achieved ‘herd immunity’ through vaccination: under this scenario there would be so few susceptible individuals that infection transmission could not be sustained.
Herd immunity and vaccines
However, Covid-19 herd immunity requires as many as 60-72% to have become immune. To achieve 72% immunity, we would need to vaccinate much more than 72% of the population, as the real efficacy of any vaccine (at preventing infection) is well below 100%.
We do not have definitive data yet but, assuming the real efficacy of the vaccines is 80%, then herd immunity would be achieved only if 75-90% of the population was vaccinated. This is currently a near-impossible task bearing in mind that 19% of the UK population is below the age of 16, and cannot be currently vaccinated, whilst 85-95% would be a realistic uptake target in the remaining age groups.
The strategy the Prime Minister presented at the press conference was not about achieving herd immunity, but about turning Covid-19 into a milder infection. If those who have received two doses have something like a 92% reduction in the risk of severe infection, then we could expect reduced number of deaths even if we lift some restrictions.
Not like flu yet
However, this approach will not yet turn Covid-19 into an infection like Influenza. The government’s scientists have modelled various lockdown exit scenarios: even under the most optimistic scenario there would be at least an additional 30,000 Covid-19 deaths, but it could be significantly worse than that.
Furthermore, the ‘optimistic’ scenario of an additional 30,000 deaths assumes that baseline measures (such as facemasks) continue. The government, though, does not seem to be keen on maintaining baseline measures after 21 June.
The other risk we face is that variants less susceptible to the current vaccines might become more common, leading to a greater surge of cases and the need to reintroduce restrictions. This is why the Prime Minister, at the end of the conference, backtracked on the promise that the lockdown exit would be irreversible. “I can’t guarantee that it’s going to be irreversible, but the intention is that it should be irreversible”.
Covid-19 is not yet like Influenza, that kills on average about 15,000 people a year in England. A number of additional strategies are required to turn it into a milder illness.
We need vaccine boosters that give protection against those known variants that are poorly covered by the current vaccines: they may become available in the autumn. We need vaccines that are given as nasal sprays as a strategy to increase vaccine uptake: some are under evaluation. We need vaccines that could be used below the age of 16: this might be the only way to achieve herd immunity and avoid disruption in schools.
To reduce the pace with which new variants are emerging, we also need to increase dramatically the vaccine production capacity across the world: we will never really be safe until we are all safe.