Why should South Africans care about the AstraZeneca Covid-19 vaccine? After all, the country’s one million AZ doses have already been redistributed to 16 African countries, who received them eagerly to protect their health-care workers.
The vials are not coming back.
What still needs attention, however, is the ongoing confusion about AstraZeneca’s safety and efficacy which has stirred mistrust over Covid-19 vaccines, worsening vaccine hesitancy.
To date the AstraZeneca vaccine has been given to more than 20 million people in the UK and Europe, 27 million people in India and tens of thousands in Africa.
Rare and severe side effects have been reported in fewer than 50 people in Europe and the UK, causing countries to pause their rollouts to investigate — and no causal link has been found to the vaccine to date.
But the stop-start decisions about AstraZeneca’s rollout (first in Europe, then in Canada and most recently in the Netherlands) have cast a shadow over the world’s most affordable vaccine — which works.
As the director of the Scripps Research Translational Institute in California, clinical scientist Prof Eric Topol, told the journal Nature: “The world, the species, depends on this vaccine. This is 2.5 billion people’s worth of vaccine.”
So what are the concerns, pros, cons and questions?
IS BLOOD CLOTTING A RISK? No, for the overwhelming majority of people
The vaccine may be linked to two very rare and serious blood clotting conditions, prompting countries to act with caution - even though no causal link has been proven to date.
The condition, cerebral venous sinus thrombosis, typically occurs in one to two people out of a million.
Early in March, Germany, followed by other countries, briefly suspended their rollout of AZ vaccinations because of the occurrence of these blood-clotting conditions.
Of the 31 cases out of 2.7 million doses given, the Paul-Ehrlich Institute, in Germany, reported that 29 were women and they were noticed in younger ages. Nine deaths were reported but no causal link was found to the vaccine.
On March 18, after investigating the reported cases, the European Medicines Agency (EMA) found the vaccine was safe and not generally “associated with a higher risk of blood clotting” and recommended that countries should resume their programmes.
The EMA recommended this condition be listed as a potential risk on the AstraZeneca packaging.
By March 24, the UK’s Medicines and Healthcare products Regulatory Agency had received 22 reports of cerebral venous sinus thrombosis, out of 18.1 million doses given. The agency declared the risk of this type of clot to be “very small”.
On March 29, Canada paused its offering of the AstraZeneca vaccine for people under 55, and the Netherlands is the latest country to take this step.
Some countries have restricted the jab for people under 55 or 60 years old, but stated that the benefits massively outweigh any risks for older citizens who are more vulnerable to Covid-19.
To put this in perspective: if 45 million adults in SA got the AZ vaccine, then there was a risk of a total of 45 to 90 people getting the blood clotting condition and possibly dying.
But so far at least 53,000 South Africans have died of Covid-19. The risk of dying of Covid-19 is therefore up to 1,000 times higher than the risk of these possible side effects.
WHAT DOES THE BIGGEST ASTRAZENECA TRIAL SHOW? 69% to 79% efficacy
On March 23, the US National Institutes of Allergy and Infectious Diseases questioned the results of a major AstraZeneca trial in the US showing 79% efficacy against symptomatic infection and 100% protection against severe disease and death.
The agency said AstraZeneca had used “outdated information”, saying the data safety monitoring board had recommended that AstraZeneca report 69% to 74% “based on more current data”.
This is the biggest trial of the vaccine to date, involving more than 32,000 people in the US, Peru and Chile. No participants died of Covid-19 or were hospitalised.
In this trial, a fifth of participants were older than 65, 22% were Hispanic, 8% Black and 4% Native American and no differences were reported in efficacy and safety.
Earlier trials in the UK, Brazil and SA had more than 20,000 participants and efficacies ranged from 60% to 70% based on pooled results and different dosing regimens.
ASTRAZENECA, J&J and NOVAVAX vs VARIANT IN SA?
If the AstraZeneca vaccine can protect against severe disease and hospitalisation, how much does it matter that a small SA trial among younger people showed no efficacy against “mild and moderate disease” caused by the B.135 variant?
Six eminent scientists from SA argued in a recent editorial in the SA Medical Journal that these results were not a reason to reject SA’s million doses.
“Even if the protection against severe disease and death afforded by the AstraZeneca vaccine ends up being just half or a third of what it is with comparator vaccines (a highly unlikely scenario), it is irresponsible to pass up the opportunity to reduce the number of deaths in the absence of alternative vaccines,” they wrote.
Top clinical scientists including Professors Glenda Gray and Linda-Gail Bekker — co-principal investigators of the J & J implementation study which has vaccinated nearly 300,000 health-care workers in the last month — point out that this may be true, but there is no scientific evidence yet to prove it.
“It is a data free zone,” said Bekker. “AstraZeneca may be effective against severe disease and death with our variant but we just don't have the data at present.”
The J & J vaccine has been proven to be 66% effective including against SA’s dominant variant (B1.351/N501Y.V2) and has the advantage of being a single-dose vaccine.
The Novavax vaccine has also been proven to work against the variant but SA has expressed no interest in securing it, or shown transparency about its decision-making on its choice of vaccines.
AZ PROS:
- 47+ million people vaccinated; side effects very rare;
- Strong protection against Covid-19, 69%-79% in latest trial results;
- Most affordable vaccine, at a couple of dollars per dose; the vaccine-sharing platform Covax has secured 170 million doses;
- Easy to store, in a fridge;
- Produced en masse at the Serum Institute in India, 3 billion doses expected by the end of 2021;
- More than 100 countries have given it regulatory approval;
AZ CONS:
- An estimated one or two people per million risk developing a very rare and serious blood clotting disorder; women under 55 years are at more risk; more than 2.8 million people have died of Covid-19 worldwide;
- Does not work against mild and moderate disease in a young population against the B. 1.351 variant dominant in SA, a small study showed;
QUESTIONS:
- Dose intervals are unclear. WHO recommends 8 to 12 weeks between jabs;
- Protection vs severe Covid-19 caused by the B1.351 variant in SA, and other variants? unknown — needs to be studied.
Clinical trials are likely to begin soon on the next-generation vaccines against all existing variants, according to AstraZeneca’s executive VP of biopharmaceuticals research and development, Mene Pangalos.
DECLARATION OF (PERSONAL) INTEREST
As a vaccine volunteer in an AstraZeneca (ChAdOx1 nCoV-19) trial in SA, I have a vested interest in the AZ vaccine.
All participants have been informed that we will be offered the AstraZeneca vaccine if the scientists get regulatory approval to go ahead with this step. Let's hope the SA Health Products Regulatory Authority expedites this process.
If I got a placebo in the trial, I will be offered the vaccine. If I got the vaccine, I will be offered a booster. I can’t wait!
