As research continues to develop new and amended coronavirus vaccines, scientists across the world are also looking at what happens when individuals are immunised with more than one type of shot.
Administering different vaccines may offer stronger immunity against Covid-19, something that is especially valuable as new variants emerge.
But before such an approach becomes routine, more findings are needed to understand the effectiveness of using more than one vaccine – and to ensure there are no serious side effects.
Trials indicate it's not only safe, but also highly effective. Evidence suggests that AZ/Pfizer mRNA is even more effective than AZ/AZ
“It seems an inherently good idea if you’re worried about the efficacy,” said Prof David Taylor, emeritus professor of pharmaceutical and public health policy at University College London.
“As the variants change, we’ll be introducing new antigens. It would be a sensible thing to do as and when a complementary vaccine becomes available.
"But we need data, we need trials.”
There are several reasons why it may be desirable to use different vaccines, including that it may lead to stronger immunity – something known as heterologous prime boosting.
When a person receives an adenovirus viral vector vaccine, such as the Oxford-AstraZeneca, there is a potential risk the immune system will react against the adenovirus. This is used as a vector to deliver coronavirus genetic material into human cells.
If this happens, when an individual is injected with the same vaccine again, some vaccine particles will be attacked by the recipient’s immune system, weakening the dose’s protective effect.
However, this will not affect mRNA vaccines – the technology behind those from Pfizer-BioNTech or Moderna.
Adenovirus viral vector vaccines use a weakened or inactivated virus to introduce coronavirus genetic material into cells, which then make coronavirus spike proteins, triggering an immune response.
The mRNA vaccines cause the body's cells to produce similar proteins, which again trigger an immune response.
Another reason to offer different doses is availability. If supplies of one vaccine dwindle, health authorities may welcome being able to give patients a different one for their second – or third – dose.
People who have had two doses of a vaccine with lower efficacy may want to have a booster of a different vaccine.
Also, concerns over rare blood clots caused by some viral vector vaccines may make it desirable to give individuals a different vaccine – such as an mRNA shot – for their subsequent shot.
This is why France announced in April that under 55s who had received the Oxford-AstraZeneca shot as their first dose would be given a Pfizer-BioNTech shot as their second, despite limited efficacy data being available. Other countries have introduced or are considering similar strategies.
Multiple trials involving giving people more than one Covid-19 vaccine are under way. Prof Zhou Xing, of the McMaster Immunology Research Centre at McMaster University, Canada, said results so far from studies in Germany and Spain are “very encouraging”.
“They indicate it’s not only safe, but also highly effective,” he said. “So far the evidence suggests that AZ/Pfizer mRNA is even more effective than AZ/AZ.”
A study published at the beginning of June looked at a cohort who received one dose of the Oxford-AstraZeneca vaccine followed eight weeks later by a Pfizer-BioNTech shot.
“We looked at neutralising antibody response: how the people that received the vaccinations responded with regards to antibodies in their blood or serum that actually neutralise virus,” said Ruediger Gross, of Ulm University Medical Centre in Germany, the first author of the study, which has yet to be peer reviewed.
Using blood sample extracts, they found that neutralisation of the Alpha variant was almost four times higher in people given the two different vaccines than it was in a group that had received two Pfizer-BioNTech doses.
"This doesn't necessarily mean that protection in the real world is fourfold higher, simply because protection for the double BioNTech vaccinated is already very high. But it indicates that it probably at least will be as good," he said.
Slight alterations in the coronavirus spike proteins generated by different vaccines may help to explain why using different shots is better than just one.
“It might help the immune system to simply see this protein from basically two different perspectives, to develop a better, broader immune response,” Mr Gross said.
Current studies involving more than one Covid-19 vaccine come with the caveat that results so far focus principally on laboratory tests.
“They show they produce good antibody response, which is important, but not the same as reducing hospitalisation and death,” said Dr Raghib Ali, director of the Public Health Research Centre at New York University Abu Dhabi.
He noted that at least one study has indicated a higher rate of side effects in people given different Covid-19 vaccines. Fever and headaches, for example, may be more common.
Giving several vaccines at once against different diseases is routine, with children receive as many as half a dozen in a single shot, but experience of giving an individual more than one vaccine against a single disease is limited, although there are precedents.
More than one vaccine has been employed against HIV, the virus that causes Aids, albeit with disappointing results.
Pharmaceutical company Johnson and Johnson created an effective two-dose vaccine against Ebola, the viral disease that has broken out several times in Africa in recent years.
The first dose uses an adenovirus viral vector, while the second employs a modified pox virus.
While more real-world efficacy data for Covid-19 vaccine combinations is awaited, Mr Gross said it may become more commonplace to give individuals more than one vaccine, particularly with third doses.
As coronavirus vaccines are largely being well tolerated, he suggests there are unlikely to be long-term side effects and he thinks it unlikely that third doses will be required to be of the same vaccine as the initial two shots.
Senior figures, such as Pfizer chief executive Albert Bourla, have suggested a third dose might be needed six to 12 months after the second, followed by annual vaccination.
However, some people who have received two doses of Covid-19 vaccines that appear to have lower efficacy may be keen to have a third shot of a different vaccine sooner than this.
In Abu Dhabi booster third vaccine doses are being made available six months after second shots.
Mr Gross said in principle there is no reason why an interval of several months is needed between second and third doses.
“I don’t think it necessarily needs to be half a year if your response to the first two vaccines was not great,” he said.
Indeed, in a study that announced findings this month, immunocompromised individuals who had reacted poorly to two doses of a vaccine were given a third shot as little as 24 days later.
In this research, one third of patients who had failed to develop antibodies after two doses did produce them after their third.
With multiple combinations of different vaccines being trialled, clinicians will be keeping a close eye on results to inform future Covid-19 vaccination strategies.
And the experiences gained during the pandemic in using more than one vaccine may offer wider benefits into the future, suggested Prof Xing.
“Since both adenoviral vector vaccines and mRNA-based vaccines are very new to us, going forward our experience in mixing them in the fight against Covid-19 certainly will lend to developing vaccines against other infectious diseases,” he said.
Production of Hayat-Vax – in pictures
The Voice of Hind Rajab
Starring: Saja Kilani, Clara Khoury, Motaz Malhees
Director: Kaouther Ben Hania
Rating: 4/5
The specs
Engine: Turbocharged four-cylinder 2.7-litre
Power: 325hp
Torque: 500Nm
Transmission: 10-speed automatic
Price: From Dh189,700
On sale: now
Dubai World Cup draw
1. Gunnevera
2. Capezzano
3. North America
4. Audible
5. Seeking The Soul
6. Pavel
7. Gronkowski
8. Axelrod
9. New Trails
10. Yoshida
11. K T Brave
12. Thunder Snow
13. Dolkong
Results
5.30pm: Maiden (TB) Dh82,500 (Dirt) 1,600m, Winner: Panadol, Mickael Barzalona (jockey), Salem bin Ghadayer (trainer)
6.05pm: Maiden (TB) Dh82,500 (Turf) 1,400m, Winner: Mayehaab, Adrie de Vries, Fawzi Nass
6.40pm: Handicap (TB) Dh85,000 (D) 1,600m, Winner: Monoski, Mickael Barzalona, Salem bin Ghadayer
7.15pm: Handicap (TB) Dh102,500 (T) 1,800m, Winner: Eastern World, Royston Ffrench, Charlie Appleby
7.50pm: Handicap (TB) Dh92,500 (D) 1,200m, Winner: Madkal, Adrie de Vries, Fawzi Nass
8.25pm: Handicap (TB) Dh92,500 (T) 1,200m, Winner: Taneen, Dane O’Neill, Musabah Al Muhairi
KILLING OF QASSEM SULEIMANI
Evacuations to France hit by controversy
- Over 500 Gazans have been evacuated to France since November 2023
- Evacuations were paused after a student already in France posted anti-Semitic content and was subsequently expelled to Qatar
- The Foreign Ministry launched a review to determine how authorities failed to detect the posts before her entry
- Artists and researchers fall under a programme called Pause that began in 2017
- It has benefited more than 700 people from 44 countries, including Syria, Turkey, Iran, and Sudan
- Since the start of the Gaza war, it has also included 45 Gazan beneficiaries
- Unlike students, they are allowed to bring their families to France
The specs
- Engine: 3.9-litre twin-turbo V8
- Power: 640hp
- Torque: 760nm
- On sale: 2026
- Price: Not announced yet
How Tesla’s price correction has hit fund managers
Investing in disruptive technology can be a bumpy ride, as investors in Tesla were reminded on Friday, when its stock dropped 7.5 per cent in early trading to $575.
It recovered slightly but still ended the week 15 per cent lower and is down a third from its all-time high of $883 on January 26. The electric car maker’s market cap fell from $834 billion to about $567bn in that time, a drop of an astonishing $267bn, and a blow for those who bought Tesla stock late.
The collapse also hit fund managers that have gone big on Tesla, notably the UK-based Scottish Mortgage Investment Trust and Cathie Wood’s ARK Innovation ETF.
Tesla is the top holding in both funds, making up a hefty 10 per cent of total assets under management. Both funds have fallen by a quarter in the past month.
Matt Weller, global head of market research at GAIN Capital, recently warned that Tesla founder Elon Musk had “flown a bit too close to the sun”, after getting carried away by investing $1.5bn of the company’s money in Bitcoin.
He also predicted Tesla’s sales could struggle as traditional auto manufacturers ramp up electric car production, destroying its first mover advantage.
AJ Bell’s Russ Mould warns that many investors buy tech stocks when earnings forecasts are rising, almost regardless of valuation. “When it works, it really works. But when it goes wrong, elevated valuations leave little or no downside protection.”
A Tesla correction was probably baked in after last year’s astonishing share price surge, and many investors will see this as an opportunity to load up at a reduced price.
Dramatic swings are to be expected when investing in disruptive technology, as Ms Wood at ARK makes clear.
Every week, she sends subscribers a commentary listing “stocks in our strategies that have appreciated or dropped more than 15 per cent in a day” during the week.
Her latest commentary, issued on Friday, showed seven stocks displaying extreme volatility, led by ExOne, a leader in binder jetting 3D printing technology. It jumped 24 per cent, boosted by news that fellow 3D printing specialist Stratasys had beaten fourth-quarter revenues and earnings expectations, seen as good news for the sector.
By contrast, computational drug and material discovery company Schrödinger fell 27 per cent after quarterly and full-year results showed its core software sales and drug development pipeline slowing.
Despite that setback, Ms Wood remains positive, arguing that its “medicinal chemistry platform offers a powerful and unique view into chemical space”.
In her weekly video view, she remains bullish, stating that: “We are on the right side of change, and disruptive innovation is going to deliver exponential growth trajectories for many of our companies, in fact, most of them.”
Ms Wood remains committed to Tesla as she expects global electric car sales to compound at an average annual rate of 82 per cent for the next five years.
She said these are so “enormous that some people find them unbelievable”, and argues that this scepticism, especially among institutional investors, “festers” and creates a great opportunity for ARK.
Only you can decide whether you are a believer or a festering sceptic. If it’s the former, then buckle up.
Specs
Engine: Electric motor generating 54.2kWh (Cooper SE and Aceman SE), 64.6kW (Countryman All4 SE)
Power: 218hp (Cooper and Aceman), 313hp (Countryman)
Torque: 330Nm (Cooper and Aceman), 494Nm (Countryman)
On sale: Now
Price: From Dh158,000 (Cooper), Dh168,000 (Aceman), Dh190,000 (Countryman)
Specs
Engine: Dual-motor all-wheel-drive electric
Range: Up to 610km
Power: 905hp
Torque: 985Nm
Price: From Dh439,000
Available: Now
OIL PLEDGE
At the start of Russia's invasion, IEA member countries held 1.5 billion barrels in public reserves and about 575 million barrels under obligations with industry, according to the agency's website. The two collective actions of the IEA this year of 62.7 million barrels, which was agreed on March 1, and this week's 120 million barrels amount to 9 per cent of total emergency reserves, it added.
The specs
Engine: 2-litre or 3-litre 4Motion all-wheel-drive Power: 250Nm (2-litre); 340 (3-litre) Torque: 450Nm Transmission: 8-speed automatic Starting price: From Dh212,000 On sale: Now
BMW M5 specs
Engine: 4.4-litre twin-turbo V-8 petrol enging with additional electric motor
Power: 727hp
Torque: 1,000Nm
Transmission: 8-speed auto
Fuel consumption: 10.6L/100km
On sale: Now
Price: From Dh650,000
Dengue%20fever%20symptoms
%3Cul%3E%0A%3Cli%3EHigh%20fever%3C%2Fli%3E%0A%3Cli%3EIntense%20pain%20behind%20your%20eyes%3C%2Fli%3E%0A%3Cli%3ESevere%20headache%3C%2Fli%3E%0A%3Cli%3EMuscle%20and%20joint%20pains%3C%2Fli%3E%0A%3Cli%3ENausea%3C%2Fli%3E%0A%3Cli%3EVomiting%3C%2Fli%3E%0A%3Cli%3ESwollen%20glands%3C%2Fli%3E%0A%3Cli%3ERash%3C%2Fli%3E%0A%3C%2Ful%3E%0A%3Cp%3EIf%20symptoms%20occur%2C%20they%20usually%20last%20for%20two-seven%20days%3C%2Fp%3E%0A
Kill%20Bill%20Volume%201
%3Cp%3E%3Cstrong%3EDirector%3C%2Fstrong%3E%3A%20Quentin%20Tarantino%3Cbr%3E%3Cstrong%3EStars%3C%2Fstrong%3E%3A%20Uma%20Thurman%2C%20David%20Carradine%20and%20Michael%20Madsen%3Cbr%3E%3Cstrong%3ERating%3C%2Fstrong%3E%3A%204.5%2F5%3C%2Fp%3E%0A
The specs
Engine: 3.8-litre twin-turbo V8
Power: 611bhp
Torque: 620Nm
Transmission: seven-speed automatic
Price: upon application
On sale: now
Benefits of first-time home buyers' scheme
- Priority access to new homes from participating developers
- Discounts on sales price of off-plan units
- Flexible payment plans from developers
- Mortgages with better interest rates, faster approval times and reduced fees
- DLD registration fee can be paid through banks or credit cards at zero interest rates
GAC GS8 Specs
Engine: 2.0-litre 4cyl turbo
Power: 248hp at 5,200rpm
Torque: 400Nm at 1,750-4,000rpm
Transmission: 8-speed auto
Fuel consumption: 9.1L/100km
On sale: Now
Price: From Dh149,900
Company Profile
Founders: Tamara Hachem and Yazid Erman
Based: Dubai
Launched: September 2019
Sector: health technology
Stage: seed
Investors: Oman Technology Fund, angel investor and grants from Sharjah's Sheraa and Ma'an Abu Dhabi
Queen
Nicki Minaj
(Young Money/Cash Money)
Women%E2%80%99s%20T20%20World%20Cup%20Qualifier
%3Cp%3E%3Cstrong%3EUAE%20results%3C%2Fstrong%3E%0D%3Cbr%3EIreland%20beat%20UAE%20by%20six%20wickets%0D%3Cbr%3EZimbabwe%20beat%20UAE%20by%20eight%20wickets%0D%3Cbr%3EUAE%20beat%20Netherlands%20by%2010%20wickets%0D%3C%2Fp%3E%0A%3Cp%3E%3Cstrong%3EFixtures%3C%2Fstrong%3E%0D%3Cbr%3EUAE%20v%20Vanuatu%2C%20Thursday%2C%203pm%2C%20Zayed%20Cricket%20Stadium%0D%3Cbr%3EIreland%20v%20Netherlands%2C%207.30pm%2C%20Zayed%20Cricket%20Stadium%0D%3C%2Fp%3E%0A%3Cp%3E%3Cstrong%3EGroup%20B%20table%3C%2Fstrong%3E%0D%3Cbr%3E1)%20Ireland%203%203%200%206%20%2B2.407%0D%3Cbr%3E2.%20Netherlands%203%202%201%204%20%2B1.117%0D%3Cbr%3E3)%20UAE%203%201%202%202%200.000%0D%3Cbr%3E4)%20Zimbabwe%204%201%203%202%20-0.844%0D%3Cbr%3E5)%20Vanuatu%203%201%202%202%20-2.180%3C%2Fp%3E%0A
Key findings of Jenkins report
- Founder of the Muslim Brotherhood, Hassan al Banna, "accepted the political utility of violence"
- Views of key Muslim Brotherhood ideologue, Sayyid Qutb, have “consistently been understood” as permitting “the use of extreme violence in the pursuit of the perfect Islamic society” and “never been institutionally disowned” by the movement.
- Muslim Brotherhood at all levels has repeatedly defended Hamas attacks against Israel, including the use of suicide bombers and the killing of civilians.
- Laying out the report in the House of Commons, David Cameron told MPs: "The main findings of the review support the conclusion that membership of, association with, or influence by the Muslim Brotherhood should be considered as a possible indicator of extremism."
