As the UK hopes to lift lockdown restrictions on 19 July 2021 the number of daily cases of COVID-19 is rising rapidly. Fuelled by the Delta variant (previously dubbed the “Indian Variant”) how worried should we be? And will the Delta variant keep us in lockdown beyond the summer?
It is important to remember that all viruses mutate again and again. There are thousands of variants of the COVID-19 virus in circulation around the world - this is normal behaviour for all viruses. Viruses change every few weeks and, whilst these changes are expected, they are unpredictable in terms of exactly what aspect of the virus will change. Most variants have such minor changes from the original virus that they are insignificant and viruses can even mutate to become weaker but a few will have more marked changes and become "variants of concern".
Variants of concern are labelled as such because they may prove more infectious and/or more lethal. They may also go unrecognised by the body's immune system, so called “escape mutants”, which means a vaccine that worked pre-mutation is no longer as effective.
What is a variant or mutation?
The word “mutation” is often used in the media and films to signify something dangerous, alien and/or deadly. Scientifically it simply means a change in the genetic makeup of a living organism. (1)
All the COVID-19 variants have mutations (or changes) in the protein spikes that project from the virus surface. These spikes are the structure the vaccines target so there is concern that changes in the spikes may render the vaccines less effective. However, the human body makes many different types of antibody in response to either infection or vaccination - known as a polyclonal response – which means it is highly unlikely a new variant will not be recognised by any of the body’s antibodies. None of the current COVID-19 variants have rendered the approved vaccines ineffective but work is ongoing to see if they reduce their effectiveness. (2)
Variants are labelled by scientists as of Interest, Concern or High Consequence. (3)
The Delta variant has now been categorised as a “Variant of Concern.” (There are no Variants of High Consequence (the most serious level) at the time of writing.)
Although cases of infection with the variant have been rising in some parts of the UK, this has been primarily in non-vaccinated people. Crucially hospital admissions and deaths have not increased in line with cases the way they did in the first two waves.
How dominant is the Delta variant?
The Delta variant was first identified in India in October 2020 and has now spread to at least 85 countries. It accounts for 90% of all cases in the UK. (4)
It is between 40 and 60 percent more transmissible than the Alpha variant (previously known as the UK variant. (5)
It is also set to become the predominant variant in the USA. Eric Topol, a professor of molecular medicine in the USA and founder of the Scripps Research Institute, describes the Delta variant as “...the most hypertransmissible, contagious version of the virus we’ve seen to date, for sure—it’s a superspreader strain if there ever was one.”
He is also concerned that the USA is poorly prepared saying, “Less than half of the nation’s population is fully vaccinated—and that number is much lower in some states, particularly in the South and Mountain West. We’ve been warned three times by the U.K.” (6)
Does the Delta variant cause more severe disease?
A study recently published in the Lancet and carried out in Scotland looked at how many people were being hospitalised with COVID-19 caused by the Delta variant. The risk of admission appeared to be doubled with the Delta variant compared to the Alpha variant. There was however insufficient data to conclude if the Delta variant was more deadly. In other words, more people were being admitted to hospital with the Delta variant than with previous variants but there was no evidence that they were more likely to die. (7)
Infections have spiked considerably in the UK but the number dying from COVID-19 is remaining very low.
Will vaccination protect against the Delta variant?
In the UK around 90% of hospitalisations are in unvaccinated people and the current spread is mostly in unvaccinated, younger people.
Vaccination appears to provide good protection against the Delta variant although one dose seems to offer less protection than it did against other variants, including the UK/Alpha variant.
UK data shows that the Pfizer vaccine is 88% effective against symptomatic disease from the Delta variant 2 weeks after the second dose. (It was 93% effective against the Alpha variant.)
2 doses of the AstraZeneca vaccine were 60% effective against symptomatic disease from the Delta variant. (It was 66% effective against the Alpha variant.)
Both vaccines were only 33% effective against symptomatic disease from the Delta variant after the first dose compared to 50% effective against the Alpha variant after one dose. (8)
However, it is important to note that these figures are for the effectiveness against symptomatic disease. If a COVID-19 vaccine is 60% effective against symptomatic disease that means the risk of becoming ill is 60% lower among vaccinated people than among those who have not been vaccinated.
A 60% effectiveness against symptomatic disease does not mean the vaccine had a 40% failure rate.
If nobody in the 40% group (who have received the vaccine but still got symptomatic COVID-19) ended up in hospital or died from COVID-19 that is not a failure.
If we look at the vaccines’ success in preventing hospital admission from COVID-19 the figures are very encouraging.
A preprint study by Public Health England has found that two doses of the Pfizer vaccine are 96% effective at preventing hospitalisation from the Delta variant. Two doses of the AstraZeneca vaccine are 92% effective at preventing hospitalisation from the Delta variant. This is comparable to the other variants.
One dose of the Pfizer vaccine was 94% effective in preventing hospitalisation and one dose of the AstraZeneca vaccine was 71% effective. (9)
So whenever a percentage is given for a vaccine’s effectiveness it is crucial to know exactly what the endpoint is that is being measured.
Israel, which has vaccinated almost its entire population with the Pfizer vaccine, is now reporting some cases of Delta variant COVID-19 in fully vaccinated adults. However the data so far shows they are less likely to be seriously ill than pre-vaccination and thus far there has not been a rise in hospital admissions or deaths in Israel. (10)
It is far less clear if either of the Chinese vaccines are effective against the Delta variant.
Many low and middle income countries are relying heavily on the Chinese vaccines but are seeing rising cases, hospitalisations and deaths from COVID-19. China has not released any of its trial data so it is impossible for scientists to assess their vaccines independently.
Their official line is that their vaccines produce a strong and effective response against the Delta variant but detailed data is yet to be provided. (11)
What is the Delta Plus Variant?
A new version of the Delta variant called “Delta Plus” is already circulating with speculation that it will be resistant to vaccines.
Delta Plus is the Delta variant with another small change on the protein spikes on the surface of the virus. However this latest change is not new, it was seen previously in the Beta variant (formerly the South African variant) and, despite media claims to the contrary, scientists do not believe it is behaving any differently to the original delta variant. (12)
Conclusion
Vaccinations in wealthier countries are working against the Delta variant of COVID-19 and the link between rising case numbers and hospital admissions and deaths has been broken. Early findings from Israel suggest that cases of COVID-19 in people who have been double dosed with either the Pfizer are less severe than pre-vaccination but more time is needed to reach a firm conclusion on this.
However, as cases in the UK continue to rise rapidly amongst the unvaccinated, younger population there is still the potential for knock on effects on hospitals if they have to admit more COVID-19 cases again. I think it is highly unlikely hospitals will reach the peaks of COVID-19 admissions seen in the two previous waves of infection but they could still come under pressure if ITU beds are taken up by younger people with COVID-19. This in turn could lead to further cancellations of routine, elective work.
The serious illness and admission numbers amongst the younger, unvaccinated people are much lower than those that were seen in the over 50s and medically vulnerable group pre-vaccination but they are not non-existent. There are currently 397,211 active cases of COVID-19 in the UK, 1,795 people are in hospital and 300 are on Intensive Care. These are not minuscule numbers. (13) (14)
Whether or not the UK can fully unlock on 19 July is dependent on the hospital figures staying stable, and ideally dropping, between then and now.
Variants will continue to appear and so far the balance seems to be tipped in favour of the vaccines, or specifically the vaccines being used in wealthier countries. However, the global spread of the Delta variant is a sure sign that the entire world needs to ramp up its vaccinations. We can all play a part in this, from the individual turning up for their vaccination appointment to the G7 and wealthier countries contributing to the equitable distribution of vaccines.
(8) https://www.gov.uk/government/news/vaccines-highly-effective-against-b-1-617-2-variant-after-2-doses
(14) https://www.worldometers.info/coronavirus/
