They spoke about a “race” between the vaccines and the virus, especially the now highly dominant Delta variant. The idea is this race will have been won by 19 July, at least enough to shift the balance such that the benefits of fully releasing restrictions and re-opening the economy would outweigh the harms and risks of the virus.
All three presenters seemed confident of this. But is this confidence warranted?
To help answer the virus side of the balance, there are five key questions:
- How effective are the different vaccines against the now dominant Delta variant, that is already some 91% of cases and rising?
- How quickly will people be vaccinated?
- How quickly are cases growing?
- What level of hospitalisations and deaths could result?
- What risk is there of a further lockdown, which the Government has promised to avoid?
This is in the context that:
- AstraZeneca has been given to most of the vulnerable and over 40s
- Pfizer is being given to adults under 40, and the most vulnerable first immunised
- Moderna is also being given to adults, mainly under 40
- There are no plans to vaccinate younger teenagers and other children, despite high prevalence rates in schools
HOW EFFECTIVE ARE THE DIFFERENT VACCINES?
It was disappointing that the effectiveness data for the Delta variant shown at the presentation was for all vaccines, and did not differentiate between them.
Presumably the Government has vaccine-specific data. Indeed Public Health England (PHE) yesterday published a ‘pre-print’ (provisional) paper titled “Effectiveness of COVID-19 vaccines against hospital admission with the Delta variant”, containing this table:
All these figures are by comparison to unvaccinated individuals. As Delta is a new variant, and there is a time lag between cases and hospitalisation, the data is based on relatively low numbers of people, so results should only be considered indicative.
The apparent weakness of AstraZeneca compared to Pfizer may simply reflect that in the real world AstraZeneca recipients are on average older or otherwise more vulnerable. It does not necessarily mean AstraZeneca is any less effective. There is no data yet published for Moderna.
It was hoped to translate these numbers into the absolute chances of vaccinated people becoming ill. Unfortunately the paper does not contain the absolute risks of symptoms and hospitalisation, either for vaccinated or unvaccinated individuals. Nor is reliable data readily available from other public sources.
It is also not clear whether the table takes into account that the body takes 2-3 weeks to develop immunity. We certainly shouldn’t assume people have the levels of immunity immediately on being given the vaccine.
But we can say that by comparison to unvaccinated people, the indicative effectiveness of vaccines against the Delta variant is as follows:
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HOW QUICKLY WILL PEOPLE BE VACCINATED?
There are two aspects to this:
- When will people be offered their first or second dose?
- How quickly will people take up the offer?
The BBC reports from the Department of Health and Social Care that by 19 July, five weeks away:
- 89% of adults should have received their first vaccine, compared to 79% now. Today it has been announced that all 18+ will be offered the vaccine by the end of this week
- 76% should have received their first vaccine, compared to 57% now.
If we assume 2-3 weeks for a vaccine to provide immunity, and linear administration of doses, the number with vaccine-induced immunity by 19 July should be around the midpoint:
- 84% from first dose
- 66% from second dose
This seems optimistic. Though at current rates of first dose vaccination, 100% could theoretically be reached by 9 July. The issue is the rate of uptake.
The PHE recently published this graph of how quickly the over-40s have been vaccinated, which is it has taken around 2 months to get to high levels of take-up. Will the under 40s be any quicker? That is the challenge.
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| Week number 2020/21 |
So conversely this means that by 19 July:
- At least 16% of all adults, mainly the younger, plus all children, will not have the protection of a first vaccine
- At least 34% of all adults will not have protection of a second vaccine
HOW QUICKLY ARE CASES GROWING?
Cases of the Delta variant are currently low but growing exponentially. The doubling time under current restrictions is little more than a week. Release the remaining restrictions and cases will grow even faster.
We now from previous experience that such doubling rates can produce very high levels of cases very quickly. This time mainly amongst younger adults and children who are mainly unvaccinated. The virus can then pass to older and more vulnerable adults, especially if unvaccinated.
We need to be aware that cases are growing rapidly despite it being the summer. Growth in the colder months of the coming autumn and winter would be expected to be much higher.
WHAT LEVEL OF HOSPITALISATIONS AND DEATHS COULD RESULT?
The need for hospitalisation is the sum of the effect of the Delta variant on:
- Those having AstraZeneca
- Those having Pfizer
- Those having Moderna
- Adults remaining unvaccinated
- Under 18s, for whom there are no plans for vaccination
Estimating the total number and phasing of hospitalisations and deaths requires a sophisticated model. What follows is simply indicative.
The Delta variant is spreading rapidly, with cases doubling in a matter of days. This presumably means a high proportion of people will be exposed to it in the coming weeks.
For AstraZeneca, as noted above, many over 40s and the vulnerable have already had two shots of the vaccine. With 92% effectiveness, few should need to go to hospital.
Most people in their 30s have had their first dose of Pfizer, and so relatively few will need hospital. Hopefully other younger people will get the vaccine, and so few should need hospital.
It is hoped that Moderna will be similar to Pfizer, using similar mRNA technology, though effectiveness is dependent on formulation.
The risk for hospitalisation and potentially death is therefore primarily about who will not be vaccinated at all by the beginning of July, adults and children. Presumably the Government has models that predict numbers and phasing that will be politically ‘acceptable’ by comparison to the benefits of releasing all restrictions on 19 July.
WHAT RISK IS THERE OF A FURTHER LOCKDOWN?
The Prime Minister has said that any easing of restrictions should not be reversible. For businesses, the need to close, wait and re-open again would be disastrous. It’s costly, especially if that were to involve businesses currently open.
Putting aside the possibility of a more dangerous variant, is the effectiveness and pace of vaccinations against Delta enough to prevent the re-introduction of restrictions? Especially as autumn and winter are only weeks away.
Let’s hope so. But it’s worth being cautious. The delay to 19 July is well justified.
OTHER ASPECTS OF HIGH CASE RATES
As ever the Government concentrates on hospitalisations and deaths whilst ignoring two other aspects of high case rates:
- High levels of Long COVID, in both adults and children. This is not only a sometimes serious problem for the individuals affected, but will put additional strain on NHS primary care and the need for specialist services
- Higher risk of new ‘variants of concern’ developing here in the UK, potentially more dangerous. This is what the Government fears
Whilst it is important to re-open the economy, letting case rates rise high carries these risks. Arguably a higher proportion of people should be vaccinated before all restrictions are released.
IN SUMMARY
Both the Pfizer and AstraZeneca vaccines are highly effective against hospitalisation. The key question is whether enough people will have been vaccinated by 19 July to justify releasing all restrictions.
It would be great for that to happen. But sadly this does seem optimistic. There are four key risks of releasing restrictions on 19 July:
- Hospitalisations and deaths could rise too high, especially amongst the unvaccinated
- LongCOVID rates, especially amongst younger people, could rise too high
- A new more dangerous variant could arise
- A further lockdown could be needed later in the year, perhaps tighter than we have now.
We will see how the data develops over the next few weeks. Maybe it would be better if:
- Some restrictions are released on 19 July
- Other restrictions remain in place a little longer until a higher proportion of people have been vaccinated. If only 'light restrictions' such as continuing to wear masks in shops and on public transport.
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