New results show broad immunity against covid-19 after nine months

2021-02-16

96 percent of those who develop antibodies to SARS-CoV-2 still carry them after nine months shows research at Danderyd University Hospital, Uppsala University and KI. The results are based on the third phase of the COMMUNITY study, examining long-term immunity after covid-19.

The COMMUNITY-stduy shows Broad immunity against covid-19 after 9 months
The COMMUNITY-study shows broad immunity against covid-19 after nine months

In the spring of 2020, samples were taken from 2,149 employees at Danderyd University Hospital. Of these, 19 percent were confirmed to have developed antibodies to SARS-CoV-2. In the third phase of the study, 1,884 people in the cohort have provided new blood samples. The results show that after 9 months, 96 percent of the 370 participants who in the spring had developed antibodies to the spike protein - which can neutralise the virus - still carry measurable levels of these.

In a sub-study, Sara Mangsbo, research director in immuno-oncology at Uppsala University's Faculty of Pharmacy, analyses how long our immune system provides protection after a covid-19 infection.

Sara Mangsbo, Faculty of Pharmacy
Sara Mangsbo, Faculty of Pharmacy

“When we are infected, our body activates T-cells that can kill virus-infected cells, direct the remaining immune system and generate lasting protection against future infections. The memory T-cells created against the virus can quickly be activated upon re-infection. By testing the COMMUNITY cohort against synthetic pieces of the coronavirus, we are able to measure how long the memory cells remain active and study the immune response over time”.

Sara Mangsbo and her research team have, together with Pierre Dönnes at SciCross, developed a synthetic peptide that can identify SARS-CoV-2 specific T-cell responses. The analysis conducted shows that the SARS-CoV-2-specific T cell memory follows the serological response.

"The ability to measure a virus-specific T cell response in blood decreases over time, but the serological response is more stable when measuring the antibodies to the spike protein, which, as mentioned, are the antibodies that can prevent the virus from infecting cells," says Sara Mangsbo.

Although circulating SARS-CoV-2-specific T cells are not measurable in all individuals over time, the cells may still remain in tissues as memory cells.

“When analysing T-cell responses, using synthetic pieces of the virus that also overlap with other coronaviruses, we can - as previously reported - also see that the immunological response is evident in more individuals than those exposed to SARS-CoV-2,” states Sara Mangsbo

In the third phase of the study, SARS-CoV-2 screening was also performed, where 340 participants with antibodies were tested once a week for a 10-week period. Viruses could be detected in less than 1 percent of the participants, which indicates a low risk of re-infection.

“By examining several components of the immune system nine months after the infection, we can see that even mild symptoms provide long-lasting and broad immunity. There has been uncertainty whether an individual with antibodies can carry the virus and spread the infection without showing any symptoms, but that risk seems very small,” says Charlotte Thålin, specialist doctor and Principal Investigator for the COMMUNITY study at Danderyd University Hospital and KI.

“In our study, we measured both antibodies and T-cell memory in all 1,884 study participants. In addition to the fact that we see that 40 percent of the entire group have had covid-19, we also see that less than 2 percent of those who do not have antibodies have signs of a SARS-CoV-2 specific T-cell memory, which suggests that antibodies to the spike protein reflect the general immunity, says Sebastian Havervall, PhD student at KI.

Facts

The COMMUNITY study is conducted and carried out in close collaboration between Danderyd University Hospital, Uppsala University, KI, KTH, SciLifeLab and the Swedish Public Health Agency.

MORE INFORMATION

CONTACT

Sara Mangsbo, research director in immuno-oncology
Faculty of Pharmacy, Uppsala University
Email Sara.Mangsbo@farmbio.uu.se


Charlotte Thålin, specialist doctor and Principal Investigator
Department of Clinical Sciences, Danderyd Hospital
E-mail: charlotte.thalin@ki.se

text: Magnus Alsne and Danderyd University Hospital
photo: Mikael Wallerstedt, Danderyd University Hospital

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Last modified: 2021-06-22