Immunization lasts a long time: Good news for the vaccine developers
Studies suggest that vaccines provide immunity over time. Meanwhile, the pharmaceutical companies Biontech and Pfizer want to deliver their vaccine with an emergency ordinance in the USA.
The duration of immunity after a coronavirus infection is crucial for the future success of a Covid-19 vaccination. For a long time, ongoing immunity was questioned. However, there is now increasing knowledge that immunity lasts for a long time. According to a comprehensive, not yet scientifically published study by the renowned US institutes La Jolla Instituts of Immunology and the Mount Sinai Clinic, even over years or decades.
Antibody levels drop
Three weeks ago, a study published in the scientific journal Science with 30,000 Covid 19 patients showed that robust, neutralizing antibodies against Sars CoV-2 infections persist for at least five months. These neutralizing antibodies lead to a sterilizing immunization. This means that a second infection is prevented and the person does not become contagious. As in other studies, it was shown that the antibody levels decrease over time. But antibodies are only part of the immune system against a virus.
Antibodies and memory cells for months
So it is good news for the vaccine developers that the new US study with 185 corona patients between the ages of 19 and 81 found not only antibodies, but also many B memory cells, so-called memory cells, eight months after the infection . These form the hidden reserve of the body’s defenses. “It’s a well-known biological phenomenon. It is not surprising that this is also the case with Covid-19, ”says Pietro Vernazza, chief physician at the Infectious Disease Clinic at the St.
Memory cells help against viruses in the long term
“With many infections, such as flu and coronaviruses, the immune system builds up a memory. These memory cells lead to a more rapid response in the event of a re-infection. ” While antibodies in the blood are required to block the virus and prevent a second infection, immune cells that remember the virus more often are responsible for preventing serious illness in the long term.
The immune response can be cellular as well as by antibodies. “The antibody response can be less active or it can drop. That doesn’t mean that the immune system can’t defend itself. A second infection is usually much milder. The severe cases observed with Covid-19 occur in old age in immunocompromised people. ” In these people, the cellular immune system is generally degraded and this makes them susceptible to viral infections. “That is the reason why elderly people die more often in the winter months,” says Vernazza.
Sars survivors still carry immune cells after 17 years
Based on their study, the US researchers assume that thanks to the immune cells, immunity could last for years. The American study authors also hope that survivors of the Sars infection, which was also caused by a coronavirus, still carried immune cells 17 years later. The Basel biomedical scientist Manuel Battegay from the management team of the Covid-19 Task Force is cautious about the assessment of the study. Whether the corona vaccination has a sterilizing effect or not cannot be answered from the previous study results. For this, the final results would have to be awaited.
It is also noteworthy that the researchers at the La Jolla Institute recognized in very few patients that their immune protection did not last long – perhaps because they were exposed to a greater viral load. However, this has no effect on the vaccine effect, because the active ingredient covers the individual variability and has a stronger effect than the body’s own immune response, the researchers write. In general, according to Vernazza, the vaccination cannot prevent the normal, biological breakdown of the immune system with increasing age. Vernazza says:
“Therefore, a flu shot becomes ineffective with age. It won’t be any different with the Covid-19 vaccination. “
The pharmaceutical companies Biontech and Pfizer explain that, according to their own analyzes, their active ingredient has the same effect across all generations and offers 95 percent protection. The companies were the first to apply for emergency approval from the US FDA yesterday. That could mean their vaccine could be delivered by the end of this year.