For the estimated six million people in Britain who have a needle phobia, it’s the news many have been anxiously waiting for.
This month, scientists in the UK will begin testing a vaccine against Covid-19 that can be squirted up the nose rather than injected into muscle, as is the case with most of the vaccines currently in trials, and the three recently approved for use in the UK.
It sounds like the perfect alternative to the discomfort and fear many experience with a jab.
For the estimated six million people in Britain who have a needle phobia, it’s the news many have been anxiously waiting for
But can spraying a Covid-19 vaccine into the nose really deliver the same potent boost to the body’s immune system that has been demonstrated with some injectable forms?
The nasal spray trial will involve 48 healthy volunteers who will be quarantined in separate rooms for up to two weeks at FluCamp, a private clinic in London, while their response to the vaccine is monitored.
This is because, unlike the injectable vaccines, the COVI-VAC nasal spray contains a genetically modified form of the Covid-19 virus itself. It’s what’s called a live attenuated vaccine — the traces of the virus that it contains are still infectious but considerably weaker than the real thing, so are very unlikely to cause any illness.
This type of vaccine is nothing new. Every year, around three million children in the UK are immunised against flu using a live attenuated vaccine — also a nasal spray.
The MMR jab against measles, mumps and rubella is a live attenuated vaccine, too.
Scientists believe live Covid-19 vaccines could be more effective than many jabs in trials which instead target one specific protein — the spike protein — found on the surface of the Covid-19 virus.
When injected into the arm, vaccines marshal the immune system’s response by stimulating cells in our bone marrow to produce antibodies
These vaccines use genetic fragments of this protein to prime the immune system to produce antibodies, which look for the protein in the blood and destroy it.
The Government has ordered millions of doses of the Pfizer and Oxford-AstraZeneca vaccines, which both work this way.
But antibodies are just one of the immune system’s numerous weapons. Live attenuated vaccines — whether in a nasal spray or an injection — work by deploying all of the infection-fighting troops, including more sophisticated T cells and B cells that can hunt down viral invaders.
It’s like calling up an entire army against the enemy rather than one platoon. ‘The rationale behind live attenuated vaccines like this one is that the patient experiences an infection that does not cause any symptoms,’ says Professor Andrew Easton, a virologist at the University of Warwick.
‘That triggers the full range of reactions from the immune system, just as you would get with a genuine viral infection. It gives you a broader immune response, which could potentially give longer-lasting immunity.’
Giving the vaccine via the nose could increase its effectiveness. When injected into the arm, vaccines marshal the immune system’s response by stimulating cells in our bone marrow to produce antibodies.
Nasal vaccines do this, but also prime cells in the mucosa — the sticky membranes lining the respiratory tract — to be on the look-out for the virus, increasing the chances of destroying it before it reaches the lungs.
‘Nasal sprays deliver the vaccine straight into the respiratory tract,’ says Professor Easton. ‘That’s where it’s most needed because that’s mostly where the Covid-19 virus replicates.’
However, the nasal route is only an advantage when vaccinating against respiratory infections. Additionally, with an injection, you know how much of the vaccine has been delivered, whereas with a nasal spray it’s harder to be sure.
And for all the excitement over a Covid-19 nasal vaccine, there is one major problem.
The flu vaccine nasal spray is not approved for use in children or adults whose immune systems are weakened by chronic illness; children under two, whose immune systems are not developed enough; and those over the age of 65. The latter is the key risk group for Covid infection.
Professor Easton warns that the same is likely to be true with the Covid-19 nasal spray, which is being developed by New York-based firm Codagenix.
This potentially rules out its use for millions of Britons most at risk of severe illness or death from the virus.
‘You have to remember you are administering a live virus and that the body’s immune system wanes as we age,’ says Professor Easton.
Scientists believe live Covid-19 vaccines could be more effective than many jabs in trials which instead target one specific protein — the spike protein — found on the surface of the Covid-19 virus
‘It can be too risky to give the elderly or very young a vaccine that could cause a full-blown infection; even though the risk is very small, it’s still there.’
Live attenuated vaccines also carry the risk of ‘reversion’ — where a virus that has been genetically modified to make it weaker gradually mutates to become highly infectious once more. In the case of the flu nasal spray vaccine, scientists spent years perfecting the formula to minimise the risk of this happening.
So, will needle-phobics be allowed to request the new nasal vaccine? In ‘exceptional circumstances’, for example, patients with learning difficulties who might become ‘seriously distressed’ about needles.
Public Health England does allow those terrified of injections to request the nasal flu vaccine, so there may be hope ahead.