The European Medicines Agency (EMA) has today approved the Oxford-AstraZeneca vaccine for use in adults over 18. The jab got the green light from the UK regulator, the MHRA, last month.
There’s been some discussion in the German and UK press this week about how effective it is for older people.
Now we know that the EMA and MHRA are in agreement: the jab is safe, and while we don’t yet have data on the precise level of efficacy in older groups, it is expected to protect elderly people from covid.
Let’s take a look at the details.
Where did those ‘less than 10% effective’ claims come from?
Two German newspapers claimed this week that official sources there expected the AstraZeneca jab to protect less than ten per cent of people aged over 65 from covid.
The German government suggested there might have been a mix-up between the proportion of study participants aged 56 to 69 (who made up 8 per cent of the sample) and the efficacy of the vaccine in older people.
But the Handelsblatt newspaper, one of those that ran the original report, insisted there was no such confusion.
We don’t know for certain, but it now looks like the stories are based on this table by STIKO, the German body tasked with working out who should get which vaccine. It puts the jab’s efficacy in the over-65s at 6.3 per cent.
But experts say the figure is useless.
According to the table, STIKO is 95 per cent confident that the true efficacy rate lies somewhere between -1,405 per cent and 94.2 per cent.
Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine says this data “is so uncertain as to be meaningless”.
Professor Paul Morgan, Director of the Systems Immunity Research Institute at Cardiff University, said: “Regarding the figure of 6.3 per cent in one of the tables in the [STIKO] document, nothing can be concluded from the data it refers to.”
But how did STIKO get such a massive range?
In order to work out whether a vaccine protects someone from covid, they need to be exposed to the virus in the first place. Professor Evans points out that most of the older participants were recruited to the study in summer 2020, when covid cases in the UK were low.
As a result, there were just two cases of coronavirus among study participants aged over 65. One was in the “control” group (and therefore didn’t get the vaccine), while the other was in the group that received the vaccine. That’s the basis of the “6.3 per cent” figure.
Professor Morgan says it “would be scientifically illiterate and wrong to quote significance on the basis of [one case of covid] in each arm of the trial.”
And this is not new information – it’s the same dataset that the Oxford-AstraZeneca researchers published in the Lancet back in December, the details of which were published on the UK government website at the time.
But while their German counterparts attempted to put a number on it, UK officials wrote: “The number of COVID-19 cases (2) in 660 participants ≥65 years old were too few to draw conclusions on efficacy”.
EMA: ‘protection is expected’
It seems the EMA and the UK regulator are in agreement.
The EMA said today: “There are not yet enough results in older participants (over 55 years old) to provide a figure for how well the vaccine will work in this group.”
But, it continued: “protection is expected, given that an immune response is seen in this age group and based on experience with other vaccines; as there is reliable information on safety in this population, EMA’s scientific experts considered that the vaccine can be used in older adults.”
A spokesperson for AstraZeneca gives a little more detail on that “immune response”: “The most recent Lancet publication has demonstrated that older adults showed strong immune responses to the vaccine, with 100 per cent of older adults generating spike-specific antibodies after the second dose.”
Though this metric is not perfect. Dr Simon Clarke, associate professor in cellular microbiology at the University of Reading, notes that while the immune response data is positive, “it does not guarantee protection against infection or disease.” He says we need to know more about what exactly makes a person immune from covid-19 before we can draw firm conclusions.
Nevertheless, Professor Evans says: “The Lancet paper made it clear that the blood test results (immunogenicity) does not suggest that there will be notably lower efficacy at older ages for the Oxford/AstraZeneca vaccine.”
He adds: “There is no reason at all for anyone in the UK or elsewhere to think that this Oxford/AstraZeneca vaccine is ineffective at any age. Its ability to be delivered to people in GP surgeries and care homes makes it a vital component in the attempts to reduce hospitalisation and deaths, especially in the elderly.”
We’ve known since it was approved by the UK regulator in December that there wasn’t yet enough data to quantify the precise efficacy of the Oxford-AstraZeneca vaccine on people aged over 65.
That’s because relatively few people in that age group took part in the study, and they were recruited later than younger participants. We’ll get more detailed figures over time.
But we now know that the UK and EU medicines regulators are in agreement that the jab is safe, and based on other immune system data, they expect it to protect elderly people from covid.