MOIRA PETTY: Why mixing your jabs could be even more effective

Mixing Covid vaccines is not only safe and effective, but could give even greater immunity than having the same vaccine twice, according to a German study published a few days ago.

The research, involving 340 healthcare workers, suggests the immune response was nearly four times greater than with two doses of the same vaccine — the theory is that the different types of vaccine (here AstraZeneca and Pfizer jabs) trigger different immune reactions.

It wasn’t the first such finding — previous trials including another in Germany and one in Spain involving 670 people, have found that an AstraZeneca (AZ) and Pfizer jab combination produced a strong immune response.

The idea of mixing vaccine types is not new. In devising a vaccination for Ebola, it was found that a mixed dose worked best, activating both the T cells and B cells of the immune system [File photo]

You only have to note the apparent hiccough in the supply of the AZ jab in April to see why health authorities might want to be able to mix jabs — to keep roll-out programmes running.

Indeed, Professor Jeremy Brown, a member of the vaccine authority, the Joint Committee on Vaccinations and Immunisation (JCVI) has already said mixing vaccines is going to be inevitable.

‘It’s practically going to have to be that way,’ he said two weeks ago. ‘Once you’ve completed a course of, say, the Moderna or Pfizer or the AstraZeneca with two doses, in the future it’s going to be quite difficult to guarantee you get the same type of vaccine again.’

But for people such as me, it’s a real and immediate concern — arguably one of life or death. That’s because I’m at risk of a stroke — I’m not unhealthy (I don’t smoke, drink alcohol moderately and have been vegetarian since I was 12) but in March last year I had Covid-19 badly.

Not so terribly that I rang 999 but seriously enough for my GP to describe it as ‘severe’. As well as complications of viral pneumonia plus bacterial pneumonia, as the months went on, I developed extreme fatigue, chest pains, liver inflammation, breathlessness, as well as losing my hair (about 60 per cent).

Then in December, I suddenly felt very dizzy. It was only 7.30pm, but all I could think of was going to bed. As my right leg wasn’t cooperating, I somehow crawled up the stairs and slept for ten hours.

The next morning, with my right side, and especially my hand, weak and feeble, I called an ambulance and was admitted to hospital. Investigations confirmed that I’d had a stroke caused by a blood clot on the right side of the brain.

Mixing Covid vaccines is not only safe and effective, but could give even greater immunity than having the same vaccine twice, according to a German study published a few days ago

Strokes are a known side effect of Covid, which makes the blood ‘sticky’ and more liable to clot. When I returned home three days later I had a big bag of pills including two blood thinners, and three drugs to lower blood pressure and a statin.

For someone who’d otherwise been so healthy it was all a bit of a shock.

I struggled with terrible side effects on my right side. I couldn’t write or type — an abysmal hindrance for a writer. I dropped and smashed things as my grip was poor, I sometimes fell over if I bent too far.

Classed as extremely clinically vulnerable, I was bumped up the queue for the Covid-19 vaccination, and in late January, I was given the AstraZeneca vaccine.

But before I could have the second, in March came news that some people had developed rare blood clots (in the brain and occasionally the stomach) after the first AstraZeneca jab.

Then in April, news that the death rate among those who developed the clots was high — 19 per cent of those affected. And in May, the AZ jab was linked to strokes.

When you’ve been devastated by a stroke, you will do anything to avoid another —so before my second AZ jab was due in late April, I contacted my GP to ask if I could have Pfizer instead.

I was told I’d been referred to a local hospital where the Pfizer jab was being offered. But the hospital said no, blaming national guidelines issued by the JCVI.

In fact, under the guidelines, mixing is allowed in some circumstances, for example, if someone had to be hospitalised after reacting badly to the first one.

On April 23, just a day after this, a friend of mine was given Pfizer having had AstraZeneca in February.

‘It was only when I looked at the card when in the ‘recovery’ room that I realised,’ he told me. He assumes they only had Pfizer to offer that day.

The idea of mixing vaccine types is not new. In devising a vaccination for Ebola, it was found that a mixed dose worked best, activating both the T cells and B cells of the immune system.

T cells destroy infected cells and B cells sweep up leftover virus and make antibodies.

A Chinese study in March revealed combinations of four Covid-19 vaccines improved immune responses in mice.

Then in mid-May the Spanish trial, with 670 volunteers, found those who’d had AZ and then Pfizer had an antibody response 30 to 40 times greater than the double AZ group.

And there is now talk of ‘mixing’ jabs with the boosters for the over-55s that seem inevitable next autumn.

But what about those like me, still waiting for their second jab, who don’t want the AZ? The question has become more pressing, as last month we learned the chance of getting the rare brain clot after a first dose of AZ has risen from one in 250,000 to one in 81,300.

Storing up trouble 

This week: Eggs

‘For optimum freshness and food safety, eggs should be kept at a constant temperature below 20c and we recommended they be kept in their original boxes in the fridge,’ says Andrew Joret, chairman of the British Egg Industry Council.

‘In the extremely unlikely event that salmonella [a bacterium] is present in an egg, storing it below 20c would minimise the risk of this multiplying.’

The box may help prevent other smells (e.g. onion) from permeating the eggs — which is why keeping them in the container is suggested.

 

The new Delta variant is thought to be more transmissible. A study led by Public Health England found that to adequately protect ourselves against it, we need two vaccinations. 

After the first dose, we are 33 per cent protected against it; this rises to 88 per cent two weeks after the second dose of Pfizer and 66 per cent after the second AZ.

I contacted the vaccination centre again but on May 25 received confirmation it won’t budge from its policy.

Just a day later came a shattering revelation: the AZ vaccine had been linked to ischaemic strokes (caused by blood clots), the type I’d had. Three people in the UK who’d suffered clots after being given the AZ jab had been admitted to hospital and one, a 35-year-old woman, had died.

The report, from the National Hospital for Neurology and Neurosurgery in London, put the chance of a blood clot at one in 100,000 doses.

But when you’ve already had a stroke, which doubles your chance of another within five years, surely it must put you at a greater than average risk of one after the AZ vaccine? I know of friends and their relatives who’d previously had blood clots refusing to have a second AZ. Should they go unvaccinated?

Professor Anthony Harnden, deputy chairman of the JCVI, suggests they should have the same vaccine ‘as there is no published data on mixing vaccine schedules’.

Two weeks ago my GP told me he was now able to refer me for a Pfizer or Moderna jab — although the JCVI guidance hasn’t changed.

Yesterday a stroke doctor confirmed I should avoid the AZ as having one stroke greatly increases your risk of a second. I can’t wait to be called up!