Protein-based vaccines will soon be another weapon in the fight against covid-19. These vaccines are well tested against other infections, Swedish researchers emphasize.
Before Christmas, the European Medicines Agency (EMA) approved a new vaccine, Nuvaxovid from Novavax. Its protective effect against serious illness and death is 90 percent, according to the Norwegian Medicines Agency.
Unlike the other vaccines, this is a protein-based vaccine. It uses an older and more conventional technology that is used in vaccines against hepatitis B, among other things.
Researchers hope that protein-based vaccines will be able to provide more long-term antibody protection, and that more people will thus also take the vaccine.
Using mRNA technology, used in the vaccines from Pfizer-Biontech and Moderna, huge amounts of doses could be produced quickly. It has saved millions of lives during the pandemic.
However, the antibodies that protect against infection have been shown to decline relatively quickly, although protection against serious illness is likely to last longer.
– Protein-based vaccines are a type of vaccine that we have used before, and from which we know any side effects. We also hope that the protection lasts a little longer compared to the mRNA vaccines, or the virus vector-based ones, where you see that the effect decreases after six months, says Ali Mirazimi, professor and vaccine researcher at Karolinska Institutet.
He adds that of course you do not know this for sure until you start vaccinating.
Need an excipient
MRNA technology introduces the molecule mRNA, which contains an “instruction template” for how the body itself can produce the proteins that it wants the immune system to respond to.
Protein-based vaccines, on the other hand, contain protein particles from the virus that are produced in the laboratory and injected together with an excipient.
– You must bring another substance that stimulates the immune system, for the body to react to this protein, it is called adjuvant, says Mirazimi.
Common to vaccines is that they stimulate the production of antibodies and memory cells, which train the immune system to recognize and block a virus. The protein vaccines can have an advantage in that they usually give a higher antibody level and thus a longer protective effect.
Know too little
So far, however, too little is known to be able to say which vaccine types are best, emphasizes Karin Loré, professor of immunology at Karolinska Institutet.
– There are many indications that protein-based vaccines provide very good levels of antibodies, but you have to wait a bit before you can say with certainty that it will make a significant difference compared to the mRNA vaccine, she adds.
That antibodies decrease over time is common to all vaccines, but the higher the levels from the start, the longer it takes before the levels are so low that they have no effect. Even with the protein vaccine, everything indicates that there will be a need for filling doses, Loré believes.
Several patient groups
Both Loré and Mirazimi see several benefits of having different types of vaccines on the market.
– It may be that people for various reasons are afraid of mRNA vaccine. Or that they feel safer taking a protein-based vaccine because it is known from before – and you know that they usually work very well, says Karin Loré.
The two experts also point out that protein vaccines can be given to patients who for various reasons can not take the other vaccines.
– Sometimes you may not be able to get a vaccine due to various medical reasons. For example, some people are super allergic and cannot take an mRNA vaccine. A protein vaccine may therefore work for some patient groups, says Mirazimi.
Can be stored in the refrigerator
Protein-based vaccines also have the great advantage of being able to be stored at a refrigerator temperature, which makes both storage and distribution much easier.
According to Loré, there is also data to suggest that protein-based vaccines tend to cause slightly fewer side effects, such as flu-like symptoms or pain in the arm. It has been discussed whether they may therefore be more relevant for children or the elderly in the future.
However, the only approved protein vaccine to date – from Novavax – is recommended for adults aged 18 and over.
An important disadvantage is that protein vaccines take longer to produce on a large scale.
– It will also take longer to update a protein vaccine to work against new variants of the virus, says Karin Loré.
It is unclear when protein-based vaccines can be used on a large scale. Vaccine coordinator Richard Bergström says that Sweden has already ordered 4.1 million doses from Novavax, but that he will be happy if Sweden receives 100,000 during the first quarter of 2022.
The end of covid-19?
Karin Loré thinks it may take some time before the production reaches the volumes needed, but hopes that the supply will eventually be so good that you can choose the vaccine yourself – or at least discuss the choice with your doctor.
She believes the protein-based vaccines may help eradicate covid-19.
– Yes, like the mRNA vaccines. If we continue to vaccinate diligently, the virus will eventually be eradicated. But I do not think that the protein-based vaccines are the miracle. What is important is that people get vaccinated, says Loré.
Mirazimi believes that the virus will not disappear completely because it is a zoonosis, an infectious disease that can be spread between animals and humans.
– But what is quite clear is that we can reduce the spread of infection and the burden on the health care system. This fight requires both vaccines and antiviral drugs. And protein-based vaccines can definitely contribute, he says.