How long do vaccines stay effective?
How long protection really takes after vaccination against COVID-19 is also influenced by the number of new variants of the virus, because in the worst case it can avoid the stimulated immune reaction. It is already clear that regular adjustments of COVID-19 vaccines will likely be necessary. Do we need new vaccines next year?
In a current study, researchers at Charité – Universitätsmedizin Berlin compared the evolution of common coronaviruses and influenza viruses, from which data on the duration of protection against vaccination can be derived. Because influenza vaccines must be adjusted annually due to the constant changes in viruses. Researchers now expect the same for COVID-19 vaccines, albeit in the hope that after a few years the intervals between vaccinations can be extended. The study was published in the specialized journal Virus evolution.
Flu vaccinations should be adjusted annually
“Influenza viruses are adept at evading human immune reactions: they change so quickly that the antibodies produced by the immune system after infection or vaccination earlier cannot identify them well,” the Charity researchers explain. A thorough vaccine modification is necessary in nearly every flu season.
Mutants can undermine immune reactions
In the case of SARS-CoV-2, first mutations such as the so-called South African variant can partially undermine the immune reaction after vaccination. “The first vaccine manufacturers are already working on developing new versions of their vaccines,” the Sharetti newspaper says. In the current study, researchers thus attempted to find out if SARS-CoV-2 would exhibit a clear long-term “flight” from the immune system like influenza viruses.
To do this, they compared the evolution of two known coronavirus strains (229E and OC43), which have been circulating in humans for a much longer period of time than SARS-CoV-2, with the evolution of H3N2 influenza viruses. For the study, the research team tracked how the spiny gene of the two longest known coronaviruses had changed over the past 40 years, and based on mutations that evolved over time, they developed a family tree for each of the coronaviruses.
Family trees in the form of a staircase
Compare this family tree with the H3N2 influenza strain tree, which avoids the human immune reaction with special efficiency. Both family trees showed a clear ladder shape. The lead author of the study, Dr. Wendy K. Jó of the Institute for Virology at Charité – Universitätsmedizin Berlin.
Antigen drift in influenza and corona viruses
According to the virologist, this is “an indication of what is called antigen drift, that is, the constant change in the surface structures through which viruses evade the human immune response.” Consequently, both coronavirus and influenza viruses frequently escape from the immune system through changes. “However, you also have to look at the speed at which this development is taking place,” the expert stresses.
Flu viruses change faster
To do this, the researchers determined the evolution rates of the three viruses. It became clear that 25 mutations per 10,000 genetic components accumulated in the flu sequence annually, while there were only about six mutations in coronaviruses. Accordingly, the common corona viruses changed four times slower than the influenza virus, which is “good news regarding SARS-CoV-2,” Professor Dr. Christian Drosten, Director of the Institute for Virology at Charité – Universitätsmedizin Berlin.
More mutations when there is a high infection rate
The rate of development of SARS-CoV-2 currently, with an estimated ten mutations per 10,000 genetic components annually, is still much higher than the coronaviruses examined, which is also reflected in the occurrence of many different viral variants around the world, according to the study leader Professor Dr. Jan Felix Drexler from the Institute of Virology at Charité – Universitätsmedizin Berlin. However, the reason for this is mainly the high level of infection during the pandemic
Where there are many infections, the virus can develop more quickly. On the basis of local cold coronavirus development rates, we assume that SARS-CoV-2 will also change more slowly once the infection process subsides – that is, after a large portion of the world’s population has acquired immune protection either through the disease itself or through vaccination. Professor Drexler confirms.
Vaccines may be used for a longer period in the future
Researchers have come to the conclusion that COVID-19 vaccines should be checked regularly during a pandemic and adjusted if necessary. Once the situation stabilizes, vaccines are expected to be usable for a longer period. Charité summarizes the results of the study: “Regular vaccine updates will be necessary during a pandemic, but after a few years, a longer lifespan of vaccines can be expected.” (fp)
Author and source information
This text complies with the requirements of the specialized medical literature, medical guidelines and current studies and has been examined by medical professionals.
- Charité – Universitätsmedizin Berlin: Should COVID-19 vaccines be adjusted regularly in the future? (Posted on March 25, 2021), charite.de
- Wendy K. Joe, Christian Drosten, Jan-Felix Drexler: Evolutionary Dynamics of Endemic Human Coronaviruses; In: Virus Evolution (veröffentlicht 20.03. 2021), Academ.oup.com
This article is for general guidance only and is not intended to be used for self-diagnosis or self-medication. He cannot replace a visit to the doctor.