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Berlin (dpa) - The idea is simple and plausible at first glance: In order to have at least some protection against Corona, as many people as possible could first get the first dose of the vaccine.
The second dose, which is necessary for better protection, would then come later than intended.
Due to the limited vaccine quantities, the Federal Ministry of Health (BMG) wants to have it checked whether such a procedure is an option for Germany.
This is also being discussed in other countries.
Experts have different opinions - also because there is a lack of data.
Important aspects:
What is it about?
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Since the end of December, certain sections of the population in Germany have been injected with the "Comirnaty" vaccine from Biontech and Pfizer.
In order for the product to offer a lot of protection, two doses must be given about three weeks apart.
It would now be conceivable to inject the second dose much later.
This could give more people a first dose - and with it at least some protection against Covid-19, so the hope.
In Great Britain, the vaccine committee responsible had recommended that as many people as possible should only be given the first dose for the time being.
The second dose can be injected twelve weeks after the first.
What exactly does the BMG want to have checked?
According to a BMG paper, the Standing Vaccination Commission has been asked to view and evaluate available data and studies on such a practice and to make a recommendation on this issue.
"Such a decision deviating from the approval requires in-depth scientific consideration and weighing."
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What is the current vaccination procedure?
Since vaccination only started in Germany at the end of December, it is not yet known that anyone would have already received the second dose regularly.
According to the European Medicines Agency, it is recommended to inject the second dose “at least 21 days” after the first.
The WHO recommends an interval of 21 to 28 days.
In the decisive phase III study on Comirnaty with around 36,000 participants, according to Biontech, the majority of the test subjects received “the second dose of vaccine as prescribed in the study protocol” - after 21 days.
The results showed that the vaccine was 95 percent effective seven days after the second dose.
This means that 95 percent fewer diseases occurred among the subjects in the vaccinated group than among those in a control group.
Why do you need a second dose at all?
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When vaccinated with Comirnaty, the body cells are stimulated to produce a certain virus component themselves.
This building block leads the body to believe that there is an infection, the immune system is activated and forms antibodies, for example.
However, this reaction is not particularly pronounced after the first dose, explains Sebastian Ulbert from the Fraunhofer Institute for Cell Therapy and Immunology (IZI).
Only after the second does a so-called boost effect occur, the immune system really jumps on and is prepared for a later infection with Sars-CoV-2.
What are the advantages of only giving the first dose initially?
If you push back the second dose, there is more vaccine available to give more people the first injection.
The hope is that this alone offers some protection.
The Society for Immunology, for example, points out that “the first vaccination from day 14 can offer considerable protection against the course of the disease”.
The second dose should not be dispensed with, but: “In this particular pandemic situation, it is justifiable to use the vaccine doses now available to enable as many people as possible to have the first immunization and the second vaccination delayed, but necessarily within 60 days to catch up. "
What is known about the protection after the 1st dose?
That was not specifically researched.
"The study was not designed to examine the effectiveness of the vaccine with just one dose," says the specialist publication for the phase III study.
The authors also write: "Nonetheless, the observed effectiveness in the period between the first and the second dose was 52 percent."
Why are there concerns about giving a large number of people one dose first?
Because, according to some experts, the data situation for such a decision is quite weak.
"I think that people are not well protected after the first injection," says Ulbert.
Published data on the immune response of volunteers would show that the body hardly produces any protective antibodies after the first dose.
There is no study with tens of thousands of test persons to correctly assess the duration and strength of the protective effect after just one dose.
He describes the information on an effectiveness of 52 percent after just one injection as "not very reliable" due to the low number of Covid 19 diseases that occurred in the study.
In addition, it is unclear how long you can postpone the second dose in order to achieve a boost effect.
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What does the manufacturer say?
Biontech stated in a statement that the phase III study examined the safety and effectiveness of the vaccine only in the event that the second dose was given 21 days after the first.
"Even if data from the study have shown that a certain protection already exists 12 days after the first vaccination, there is so far no data that protection is maintained after the first dose beyond 21 days."
And the licensing authority?
The EMA in Amsterdam is responsible for corona vaccines in the EU.
In an email, the authorities stated that the recommendations for the vaccination procedure were based on data from the phase III study.
In this study, the interval between the two doses was a maximum of 42 days.
If the interval were to be increased to around six months, “this would make a change in the conditional marketing authorization and more clinical data” necessary.
So far there is no data to show that there is protection after the first dose that lasts for two to three weeks.
The EMA counterpart in the US, the FDA, warns against deviating from the prescribed administration of the two doses.
Possible changes in this process, such as reducing doses or lengthening the intervals, could pose a threat to public health.
Changes could only be considered if there were scientifically sound data on them.
If the vaccination is insufficient, can it be that the coronavirus becomes resistant to the vaccine?
The expert Ulbert considers this to be “extremely unlikely”.
In his assessment, fears in this direction are based on experience with antibiotics.
Bacteria can develop resistance to these substances comparatively easily by changing the exact location of a protein where the drug attacks.
With the corona vaccines, however, the situation is different.
The corona antibodies formed by the body are very diverse and bind the virus in many different places.
In order to make the vaccine ineffective, the virus would have to change in all of these places.
© dpa-infocom, dpa: 210106-99-914789 / 2
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Phase III results in NEJM
UK Vaccine Committee Recommendations
Product information on Comirnaty at Ema (4.2., 4.2. And 5.2.)