Peggy Riese: “The corona vaccines were meant to protect against severe disease. And that is what they do”
Dr. Peggy Riese is a scientist in the Department of Vaccinology and Applied Microbiology at the Helmholtz Centre for Infection Research (HZI) in Braunschweig. She conducts research on the specifics of the immune system in interaction with vaccines. In this interview, she talks about current developments in SARS-CoV-2 vaccine research.
The mRNA vaccines are currently considered the gold standard among corona vaccines. A protein vaccine has recently been approved. How does it work, and how should it be viewed in terms of its effectiveness?
Protein vaccines belong to the classic types of vaccine, like those we are familiar with from flu vaccines, for example. The new protein vaccine Nuvaxovid contains the spike protein of SARS-CoV-2 and an additional immune modulator promoting the activation of the immune response. The results of the clinical trials are quite promising: They show that vaccinated people are very well protected against developing a severe course of the disease. Unfortunately, much like its mRNA counterparts, this vaccine does not protect against infection. Only time will tell whether or not the immune response will last over an extended period of time.
Do we already know more about this for the mRNA vaccines?
What we do know about the efficacy of mRNA vaccines is that they provide good protection against severe disease for about three to six months. After that, they should receive a booster. This is the case because these vaccines primarily address the so-called humoral immune response. This is the part of our immune system that is responsible for rapid production of precision-fit antibodies. Although, of course, this is enormously important in the fight against a pathogen, it sadly is not enough to build up long-term immunity. This requires the activation of the so-called cellular immune response: Memory cells that remember unwelcome invaders even years after an infection and can quickly produce antibodies when they re-encounter the same pathogen. This immunological memory seems to be only weakly activated by the mRNA vaccines. We do not yet understand why this is the case. But let me stress the following: The corona vaccines developed so far were primarily intended to protect against severe disease. And they do – they have achieved their original goal.
With its new mutations, doesn't the virus also outrun the effectiveness of the vaccination?
Yes, unfortunately this is true. The vaccines available today are based on the spike protein of the original virus strain from 2019. And both, the delta variant and the new omicron variants, include a considerable number of mutations in the spike protein. This causes the antibodies produced in the course of a vaccination to no longer fit optimally. It was a surprise to scientists that SARS-CoV-2 was able to change so quickly because the coronaviruses we know from harmless colds do not do this to the same extent. I don't like to compare Corona and influenza, but the challenge of having to adapt vaccines on a regular basis because the pathogen changes so quickly now seems to be evident with SARS-CoV-2 as well. Currently, some clinical trials on mRNA vaccines adapted to the omicron variant are already underway.
Are there any other promising candidate vaccines currently under development?
Yes, for example the vaccine called VLA2001, which is currently going through the regulatory process. It is a so-called inactivated whole-virus vaccine. The core of the vaccine is a complete, inactivated SARS-CoV-2 virus, whose multiple targets should trigger a broader immune response. Furthermore, there is an interesting study from the USA on a vaccine that contains spike proteins of several virus variants and might thus stimulate the development of broader immune protection against different variants of SARS-CoV-2. You see, the development of new corona vaccines remains exciting.
SARS-CoV-2 has taken the research labs virtually by storm in the past two years – has it found a place in your research as well?
Yes, of course. We aim to understand why the immune response after vaccination is better in some people than in others. As part of this work, we are also looking for differences between different vaccines and vaccine combinations after the first, second or third vaccination. We are particularly interested in the immune mechanisms in humans that might explain why the vaccine response can vary so strongly. We have been investigating this for some time using the influenza vaccine as an example and are now including Corona in our studies. In addition, we are doing research on the development of next-generation corona vaccines. In this context, we are focussing primarily on vaccinations via the mucous membranes – for example as a spray acting on the nasal mucosa – aiming to perhaps get a future vaccine that protects against infection as well.
In your view, has the Corona pandemic been a booster for vaccine research?
Oh yes, I would fully subscribe to that. But that is also the only good thing to emerge from the pandemic. The sudden appearance of a previously unknown and dangerous pathogen has shown: We need forward-looking research. We can't just start when the pandemic is in full swing already. In order to be able to counteract pathogens, basic research in the literal sense is fundamental. The more we know about viruses, bacteria and how our immune system works, the faster and more efficiently we can produce vaccines. Of course, another important component is good interdisciplinary and international cooperation. And this has indeed been evident during the past two years of the pandemic: The scientific community has moved closer together and is exchanging ideas better than ever before.
Interview: Nicole Silbermann
Publication: May 2022