Long-term immunity after COVID-19
One of the big questions that still need to be answered about the corona pandemic is: How long does immunity against COVID-19 last after a SARS-CoV-2 infection or after a vaccination? Results so far indicated that immune protection persists for at least six months. Now a German research team has published more recent data that paint a more optimistic picture.
Researchers from the University of Lübeck and the Health Department of the Hanseatic City of Lübeck have completed another study on the duration of immunity after a COVID-19 infection. It was found that the immune protection after COVID-19 still persists in a majority of the people examined after ten months. A pre-release version of the study can be downloaded from the medical pre-release server “medRxiv“Can be viewed.
How does the body generate SARS-CoV-2 immunity?
The aim of the study was to clarify whether and for how long infected people produce antibodies and interferon-gamma (IFN-γ) after a SARS-CoV-2 infection in order to have a sufficient defense mechanism against the pandemic coronavirus.
According to the study, the acquired immune protection against COVID-19 consists of a combination of cell immunity and antibodies. On the one hand, the body develops specific anti-SARS-CoV-2 IgG antibodies as part of a SARS-CoV-2 infection or a vaccination. In addition, so-called T lymphocytes (T cells) produce IFN-γ, one of the most important messenger substances in the immune system.
What was investigated?
The Lübeck working group analyzed the blood of 412 participants who had experienced predominantly mild or moderate symptoms after a SARS-CoV-2 infection. Using the antibodies and the IFN-γ messenger substances, the team was able to provide a statement about the average minimum duration of immunity.
Immune defense against SARS-CoV-2 after ten months
The participants’ blood was examined ten months after the SARS-CoV-2 infection. It was found that 316 of 412 people (76.7 percent) still had both antibodies (IgG) and IFN-γ messenger substances in their blood. 300 days after the coronavirus infection, an average of 50 percent of the immune defense against COVID-19 was still active.
Some participants had either high antibody levels but low IFN-γ levels or vice versa. The researchers have not yet found an explanation for this observation. The phenomenon will now be investigated further.
Immunity lasts longer than previously thought
“Our data show that almost all participants had an adequate immune reaction after they had been infected with COVID,” explains Professor Dr. Werner Solbach from the Center for Infection and Inflammation Research at the University of Lübeck. The protection lasts for at least ten months after infection. The results could help in deciding whether and at what intervals a booster vaccination is necessary.
Measure antibodies and IFN-γ
“In our joint study, in addition to the established antibody test, we followed the approach of being able to make a statement about so-called cellular immunity, that is, the defense situation at the cellular level, with the help of IFN-γ measurement”, adds Dr. Alexander Mischnik, head of the Lübeck health department and last author of the study.
The results are reassuring and allow the conclusion that only by looking at antibodies and cell immunity can a statement be made about how long one is protected after a COVID infection.
Limitation of the study results
The study results have so far only been presented in advance. A so-called peer review by independent scientists and a publication in a renowned specialist journal is still pending. (vb)
Author and source information
This text complies with the requirements of specialist medical literature, medical guidelines and current studies and has been checked by medical professionals.
Diploma-Editor (FH) Volker Blasek
- Julia Schiffner, Insa Backhaus, Jens Rimmele, et al.: Long-term course of humoral and cellular immune responses in outpatients after SARS-CoV-2 infection; in: medRxiv, 2021, medrxiv.org
- University of Lübeck: New data on long-term immunity of people infected with COVID-19 (published: June 29, 2021), uni-luebeck.de
This article is for general guidance only and is not intended to be used for self-diagnosis or self-treatment. He can not substitute a visit at the doctor.