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Ampoule with corona vaccine: advantage of easy handling
Photo: John Cairns / University Of Oxford / dpa
On Monday, the third corona vaccine manufacturer announced the first results from larger studies on humans.
According to this, the vaccine, which the British pharmaceutical manufacturer AstraZeneca developed in collaboration with the University of Oxford, could protect about 70 percent against Covid-19 disease.
The information on efficacy varies greatly depending on the vaccination schedule - i.e. the type and dose with which vaccination is carried out.
In a press release, the developers announced interim results from two clinical studies.
In a combined Phase II and Phase III trial, 2,741 subjects in the UK received the vaccine or an ineffective placebo.
The vaccination was carried out in two steps.
Doctors first gave the subjects in the vaccination group half a dose of the active ingredient and a month later a full dose.
Effectiveness between 60 and 90 percent
According to the press release, 90 percent of the Covid 19 cases in the vaccine group could be prevented in this way.
However, it is not clear how many Covid 19 diseases there were in absolute terms among those vaccinated with the active ingredient compared to the placebo group.
The data should be published in the next few days.
Only then can it be said on which database the number is based.
An efficacy of 90 percent would be in a similar order of magnitude as the manufacturers Biontech / Pfizer and Moderna claim for their vaccines.
They name an effectiveness of up to 95 percent (read more about this here and here), Biontech and Pfizer have already applied for emergency approvals in the USA.
In a second vaccination scheme, however, the AstraZeneca / Uni-Oxford vaccine performed significantly worse.
In a phase III study with 8,898 test subjects in Brazil, the experts administered two full doses of the vaccine.
The effectiveness here was around 60 percent.
On average, the vaccine has so far shown an effectiveness of 70 percent from both studies, according to the company.
The figures are based on a total of 131 Covid-19 cases, the greater part of which occurred in the placebo group, but also affected those vaccinated with the active ingredient more often than in the studies by the other manufacturers.
No serious side effects
Biotech / Pfizer and Moderna had made the data from their corona vaccination studies public after a similar number of cases.
However, they have already vaccinated more people overall, so that they have a larger dataset on side effects, for example.
Nevertheless, AstraZeneca is confident: There were no serious side effects among the vaccinated, it said.
The company had previously had to interrupt its vaccination studies twice because test subjects fell ill, but experts found no causal link with the vaccination.
The company also plans to apply for approvals in several countries around the world soon and register the vaccine with the WHO for rapid use in poorer countries.
The phase III studies are also to be adapted so that the vaccination schedule with half the dose is tested in larger studies.
Advantage of simple storage
The basis of the AstraZeneca / Uni-Oxford vaccine called AZD1222 or ChAdOx1 nCoV-19 is an attenuated cold virus from chimpanzees.
It contains genetic material from a surface protein with which the Sars-CoV-2 pathogen docks onto human cells.
When the immune system comes into contact with this protein, it forms targeted antibodies and T cells.
In contrast to vaccines from Biontech / Pfizer and Moderna, the agent does not belong to the mRNA vaccines, but to the so-called vector vaccines.
The principle has been known for a long time and has a decisive advantage: The vaccine can be stored in the refrigerator and, unlike the mRNA products, does not need double-digit minus degrees (read more here).
This makes storage and transport easier.
This could make the vaccine important, even if it is slightly less effective.
"AZD1222 is robust and easy to use, so to speak the worker bee among the potentially available vaccines against Covid-19," said Clemens Wendtner from the Munich Clinic Schwabing to the Science Media Center.
The vaccine can be safely stored in the refrigerator at two to eight degrees Celsius for six months.
"This should make vaccination campaigns easier in countries with fewer resources for complex cold chains."
In any case, the world is not getting along with a corona vaccine, said vaccine researcher Andrew Pollard from Oxford University, who was involved in the vaccination test, in a press briefing.
No company has the capacity to quickly make enough vaccine available to the entire world population.
AstraZeneca has already prepared to mass-produce its vaccine.
Production manager Pam Cheng said 200 million cans could be delivered this year.
The production of three billion cans will be possible in 2021.
Switching production in parts to half cans at short notice is not a problem.
Details unclear
As with the other manufacturers, however, the AstraZenca study cannot answer all questions.
It is still unclear how reliably the vaccines not only prevent Covid-19, but also infections with the Sars-CoV-2 coronavirus.
According to a press release from Oxford University, there are initial indications of infection protection in connection with the active ingredient that it helped to develop.
The final results are not yet available.
Also, no data is yet public showing how well the vaccines work in different age groups.
An evaluation of the first results of their vaccination study in Great Britain published last week by Oxford researchers in the specialist magazine "The Lancet", however, at least raises hope that the vaccine will also work well in the elderly.
In the phase II study, there was a good immune response in participants both under and over 56 years of age, the researchers write.
The vaccine was even better tolerated by the elderly than by the younger ones.
According to the information, around 240 of the 560 healthy study participants included in the analysis were over 70 years old.
According to AstraZeneca and Oxford University, there were no severe courses of Covid-19 in their studies among those vaccinated with the active ingredient.
How much rarer they were compared to the placebo group remains open.
So it is not possible to say how many serious illnesses the vaccine prevented.
The full data on the studies, which are not yet public, should soon provide answers to some of these questions.
Mystery of the benefit of half the dose
Researchers are still puzzling, however, why, of all things, the vaccination schedule with half a dose at the beginning showed better effectiveness.
That was not immediately obvious, explained Gerd Fätkenheuer from Cologne University Hospital to the Science Media Center.
“Is that a purely coincidental effect?
Or are there immunological factors that justify this? "
Clemens Wendtner from the Munich Clinic Schwabing suspects that the immune system may react to the carrier virus from the monkey and that the vaccine effect is weakened as a result.
If the first vaccine dose is too high, the body may fight the carrier virus with the second vaccination.
Oxford vaccination researcher Pollard explained that vaccinations for infants, whose immune system does not in principle know any pathogens, are often more effective with a lower initial dose.
It is conceivable that it is similar in adults who come into contact with a completely new virus.
However, the experts agree that more data is needed for a clear answer.
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With material from dpa