Researchers are recruiting thousands of UK volunteers for the final stage clinical trial of a candidate coronavirus vaccine that is being manufactured in Scotland.

Doctors plan to give the Valneva vaccine to 4,000 adults from the beginning of May in a phase 2/3 trial that will run from more than 20 sites across England and two hospitals in Edinburgh and Glasgow.

The move follows promising early stage trial results, which found that two shots of the vaccine produced a good immune response without raising safety concerns. If it performs well in the new trial, Valneva hopes to seek approval as soon as the summer, paving the way for potential booster shots this autumn.

More than half the UK population has received at least one dose of coronavirus vaccine. The rollout includes shots from Pfizer/BioNTech, Oxford/AstraZeneca and Moderna, but adding further vaccines to Britain’s armoury will boost resilience against any manufacturing and supply glitches and the risk that some vaccines may fail against new variants.

“You want several tools in your toolbox in case you have problems,” said Prof Adam Finn, a paediatrician at Bristol University and chief investigator on the Valneva trial. “You want to have not just a number of vaccines, but a number of vaccines that employ different approaches.”

The French company’s vaccine is being produced for the UK in Livingston, West Lothian. Encouraged by early trial data, the government recently upped its original order from 60m to 100m doses, matching the number of shots on order for the Oxford/AstraZeneca vaccine. Valneva said it could manufacture up to a further 150m shots for the rest of the world.

Valneva’s vaccine is based on a more traditional technology than those now being rolled out in Britain. It uses an inactivated coronavirus virus to stimulate the immune system, an approach developed more than 50 years ago for polio and which is used in flu, rabies and hepatitis A vaccines. Because the vaccine incorporates the whole virus, rather than only the surface spike protein, it may produce broader protection against the disease and worrisome variants that have mutations in the spike protein.

The 13-month trial will assess whether the Valneva vaccine produces more neutralising antibodies against the coronavirus than the AstraZeneca shot. Researchers aim to recruit 1,000 people aged 18 to 29 who will receive the Valneva vaccine, and 3,000 older adults who will receive either Valneva or AstraZeneca.

Quick Guide

Covid vaccine side-effects: what are they, who gets them and why?


What are the most common side-effects from the Covid vaccines?

According to Public Health England, most side-effects from the Covid vaccines – Pfizer/BioNTech and Oxford/AstraZeneca – are mild and short-lived. These include soreness where the jab was given, feeling tired or achy and headaches. Uncommon side-effects include having swollen lymph nodes.

Why do the common side-effects occur?

“The sore arm can be either due to the trauma of the needle in the muscle, or local inflammation in the muscle probably because of the chemicals in the injection,” said Prof Robert Read, head of clinical and experimental sciences within medicine at the University of Southampton and director of the NIHR Southampton Biomedical Research Centre.

“The other common side-effects – the muscle aches, flu-like illness and fatigue – are probably due to generalised activation of the immune system caused by the vaccine. What this means is that the white blood cells that are stimulated by the vaccine to make antibodies themselves have to secrete chemicals called cytokines, interferons and chemokines, which function to send messages from cell to cell to become activated.”

Are blood clots a side-effect of the vaccines?

The Oxford/AstraZeneca jab has been linked to a small but concerning number of reports of blood clots combined with low platelet counts (platelets are cell fragments in our blood that help it to clot). Distribution of the Johnson & Johnson vaccine has been “paused” in the US while scientists investigate six incidences of a rare type of blood clot.

These include a rare clot in the brain called cerebral venous sinus thrombosis (CVST). In an unvaccinated population, upper estimates suggest there may be 15 to 16 cases per million people per year.

The Medicines and Healthcare products Regulatory Agency (MHRA) said recipients of the Oxford/AstraZeneca jab should look out for new headaches, blurred vision, confusion or seizures that occur four days or more after vaccination. The MHRA also flagged shortness of breath, chest pain, abdominal pain, leg swelling and unusual skin bruising as reasons to seek medical advice.

Up to and including 31 March, the MHRA said it received 79 reports of cases of blood clots combined with low platelets, including 19 deaths, following more than 20m doses of the Oxford/AstraZeneca jab. That equates to about four cases for every million vaccinated individuals.

Two cases of blood clots with a low platelet count have also been reported among recipients of the Pfizer/BioNTech jab. The European Medicines Agency is also examining three cases of venous thromboembolism blood clots involving the Johnson & Johnson jab.

The MHRA says blood clots combined with low platelets can occur naturally in unvaccinated people as well as in those who have caught Covid, and that while evidence of a link with the Oxford/AstraZeneca vaccine has become stronger, more research is needed.

Nicola Davis Science correspondent

All participants will receive two shots of vaccine four weeks apart. For those aged 30 and above, neither they nor their doctors will know which vaccine they have received during the course of the trial. After both shots have been given, researchers expect those taking part to have four or five follow-up visits for blood and saliva tests.

The Valneva vaccine is the only whole virus, inactivated and adjuvanted vaccine candidate in clinical trials in Europe. An adjuvant is an ingredient that helps to create a stronger immune response. While the trial is open to older adults, the vast majority of over-50s in the UK have already been offered a vaccine. More data on older individuals will be gathered from a parallel trial in Australia.

“If we don’t slip in any way and keep on track, we want to get this to the regulators in the summer so that we have the vaccine available in the autumn if we need it,” said Finn.

Many manufacturers have started work on second-generation jabs to target new variants of the virus that appear to be partially resistant to the vaccines being rolled out around the world.

The UK vaccines minister, Nadhim Zahawi, told MPs in February that the Valneva vaccine could serve as an effective booster in the autumn because it used an approach thought to be more effective against mutants. Further work this year will assess the safety of using Valneva as a booster in people who have already received shots of other vaccines.

This content first appear on the guardian

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