Medicine at KI DS

The COMMUNITY (COVID-19 Immunity) Study was initiated in April 2020 and comprises a large longitudinal cohort including 2149 healthcare workers and 118 hospitalized COVID-19 patients. The overall aim is to obtain deep understanding of the generation and dynamics of SARS-CoV-2 immunity (humoral and cellular) following infection and/or vaccination.

Inside COMMUNITY lab in Danderyd Hospital
The COMMUNITY lab at Danderyd Hospital Photo: Ludvig Kostyál


Blood and airway samples are obtained every four months, and relevant clinical data are mapped by continuous data collection through a smart-phone app system. Data on vaccination and SARS-CoV-2 infections are obtained from national registers. Substudies, such as regular qPCR screening studies are conducted in subgroups.

The majority of study participants are now vaccinated with either Pfizer's mRNA vaccine BNT162b2, Astra Zeneca's adenovirus vector vaccine ChAdOx1 nCoV-19, and/or Moderna’s mRNA vaccine mRNA-1273.

Key results

  • Symptomatic infection with SARS-CoV-2 variant BA.2.86 induces a stronger mucosal IgA response to wild-type and BA.5 spike proteins as compared with serum IgG binding to these same proteins
    Mucosal and Serum Antibodies 3 Weeks after Symptomatic BA.2.86 Infection.
    Bladh O, Greilert-Norin N, Havervall S, Marking U, Aguilera K, Alm JJ, Blom K, Åberg M, Klingström J, Thålin C
    N Engl J Med 2023 Oct;389(17):1626-1628
  • A fourth mRNA vaccine dose against SARS-CoV-2 increases serum and nasal IgG levels but fails to enhance mucosal IgA responses, regardless of prior infection status. 
    Mucosal immune responses following a fourth SARS-CoV-2 vaccine dose.
    Bladh O, Marking U, Havervall S, Norin NG, Aguilera K, Hober S, Smed-Sörensen A, Gordon M, Blom K, Åberg M, Klingström J, Thålin C
    Lancet Microbe 2023 Jul;4(7):e488
  • Mucosal IgA antibodies are strongly correlated with protection against infection with SARS-CoV-2 BQ.1 and BQ.1.1 variants, while serum IgG levels show no significant association with protection in multivariate analysis.
    Mucosal IgA protects against BQ.1 and BQ.1.1 infection.
    Marking U, Bladh O, Havervall S, Greilert-Norin N, Gordon M, Alm JJ, Blom K, Åberg M, Klingström J, Thålin C
    Lancet Infect Dis 2023 Aug;23(8):e272-e273
  • Ongoing SARS-CoV-2 Omicron transmission was observed among highly vaccinated healthcare workers in Sweden in 2023, emphasizing the importance of continued surveillance for seasonal effects and emerging virus variants.
    Point prevalence of SARS-CoV-2 infection among healthcare workers in March and June 2023 in Sweden.
    Blom K, Bladh O, Havervall S, Marking U, Greilert Norin N, Alm JJ, Klingström J, Thålin C
    Lancet Reg Health Eur 2023 Oct;33():100725
  • High levels of mucosal IgA antibodies in the airways provides protection from SARS-CoV-2 infection for a period of at least eight months. “7-month duration of SARS-CoV-2 mucosal immunoglobulin-A responses and protection”. Ulrika Marking, Oscar Bladh, Sebastian Havervall, Julia Svensson, Nina Greilert-Norin, Katherina Aguilera, Martha Kihlgren, Ann-Cristin Salomonsson, Maja Månsson, Radiosa Gallini, Cecilia Kriegholm, Philip Bacchus, Sophia Hober, Max Gordon, Kim Blom, Anna Smed-Sörensen, Mikael Åberg, Jonas Klingström, Charlotte Thålin. The Lancet Infectious Diseases, correspondence, online January 12 2023, doi:…
  • High levels of mucosal IgA antibodies in the airways reduce the risk of being infected by omicron, but many did not receive detectable antibodies in the airways despite three doses of the SARS-CoV-2 vaccine. These findings shed light on the potential utility of novel nasal vaccines. ”Anti-Spike Mucosal IgA Protection against SARS-CoV-2 Omicron Infection”, Sebastian Havervall, Ulrika Marking, Julia Svensson, Nina Greilert Norin, Philip Bacchus, Peter Nilsson, Sophia Hober, Max Gordon, Kim Blom, Jonas Klingström, Mikael Åberg, Anna Smed-Sörensen, Charlotte Thålin. The New England Journal of Medicine (NEJM), Letter to the Editor, online 14 september 2022, doi: 10.1056/NEJMc2209651
  •  Healthcare workers are at increased risk of SARS-CoV-2 infection. Most people who became infected with SARS-CoV-2 experienced mild or no symptoms. Early on, we were able to establish the correlation between loss of smell, taste and COVID-19. SARS-CoV-2 exposure, symptoms and seroprevalence in healthcare workers in Sweden.
    Rudberg AS, Havervall S, Månberg A, Jernbom Falk A, Aguilera K, Ng H, Gabrielsson L, Salomonsson AC, Hanke L, Murrell B, McInerney G, Olofsson J, Andersson E, Hellström C, Bayati S, Bergström S, Pin E, Sjöberg R, Tegel H, Hedhammar M, Phillipson M, Nilsson P, Hober S, Thålin C
    Nat Commun 2020 10;11(1):5064
  • One in ten participants with mild COVID-19 report a diversity of long-term symptoms which disrupt work, social, and home life. Symptoms and Functional Impairment Assessed 8 Months After Mild COVID-19 Among Health Care Workers.
    Havervall S, Rosell A, Phillipson M, Mangsbo SM, Nilsson P, Hober S, Thålin C
    JAMA 2021 05;325(19):2015-2016
  • Broad and efficient SARS-CoV-2 immunity 8 months post mild infection. Robust humoral and cellular immune responses and low risk for reinfection at least 8 months following asymptomatic to mild COVID-19.
    Havervall S, Ng H, Jernbom Falk A, Greilert-Norin N, Månberg A, Marking U, Laurén I, Gabrielsson L, Salomonsson AC, Aguilera K, Kihlgren M, Månsson M, Rosell A, Hellström C, Andersson E, Olofsson J, Skoglund L, Yousef J, Pin E, Lord M, Åberg M, Hedhammar M, Tegel H, Dönnes P, Phillipson M, Nilsson P, Klingström J, Mangsbo S, Hober S, Thålin C
    J Intern Med 2022 01;291(1):72-80
  • T cells are an important part of our immune system, but T cell tests remain of limited value in individual diagnostics. An evaluation of a FluoroSpot assay as a diagnostic tool to determine SARS-CoV-2 specific T cell responses.
    Mangsbo SM, Havervall S, Laurén I, Lindsay R, Jernbom Falk A, Marking U, Lord M, Buggert M, Dönnes P, Christoffersson G, Nilsson P, Hober S, Phillipson M, Klingström J, Thålin C
    PLoS One 2021 ;16(9):e0258041
  • A single dose adenovirus-vectored ChAdOx1 nCoV-19 elicits strong humoral immune responses in SARS-CoV-2 recovered study participants. Antibody responses after a single dose of ChAdOx1 nCoV-19 vaccine in healthcare workers previously infected with SARS-CoV-2.
    Havervall S, Marking U, Greilert-Norin N, Ng H, Gordon M, Salomonsson AC, Hellström C, Pin E, Blom K, Mangsbo S, Phillipson M, Klingström J, Hober S, Nilsson P, Åberg M, Thålin C
    EBioMedicine 2021 Aug;70():103523
  • Considerable decline in neutralizing antibodies after both BNT162b2 and ChAdOx1 nCoV-19 vaccination over 3-7 months. Neutralizing antibody titers against all ten tested SARS-CoV-2 variants were at least 2 respectively 3-fold higher in SARS-CoV-2 recovered as compared to naive vaccinees following BNT162b2 and ChAdOx1 nCoV-19, respectively. Impact of SARS-CoV-2 infection on vaccine-induced immune responses over time.
    Havervall S, Marking U, Greilert-Norin N, Gordon M, Ng H, Christ W, Phillipson M, Nilsson P, Hober S, Blom K, Klingström J, Mangsbo S, Åberg M, Thålin C
    Clin Transl Immunology 2022 ;11(4):e1388
  • High rate of omicron breakthrough infections among triple vaccinated healthcare workers. High viral replication despite three vaccine doses and mild symptoms. MedRxiv (DOI: 10.1101/2022.04.02.22273333) and Infection Rate of SARS-CoV-2 in Asymptomatic Healthcare Workers, Sweden, June 2022.
    Blom K, Havervall S, Marking U, Norin NG, Bacchus P, Groenheit R, Bråve A, Thålin C, Klingström J
    Emerg Infect Dis 2022 Aug;28(10):
  • Serological responses to Omicron breakthrough infection in triple vaccinated healthcare workers are hampered by prior infection. Immune responses after omicron infection in triple-vaccinated health-care workers with and without previous SARS-CoV-2 infection.
    Blom K, Marking U, Havervall S, Norin NG, Gordon M, García M, Tecleab T, Christ W, Forsell M, Phillipson M, Nilsson P, Mangsbo S, Hober S, Åberg M, Klingström J, Thålin C
    Lancet Infect Dis 2022 07;22(7):943-945

The COMMUNITY project is financed by Jonas and Christina af Jochnick Foundation, Region Stockholm, Folkhälsomyndigheten, Lundblad Family Foundation, Hjärtlung fonden, and Knut and Alice Wallenberg Foundation.

The COMMUNITY study team

Profile image

Nina Greilert

Project Manager, Research Nurse
Profile image

Sebastian Havervall

M.D., Ph.D. Student
Profile image

Max Gordon

M.D., Ph.D.
Profile image

Oscar Bladh

M.D, PhD student

Ann-Christine Salomonsson, Biomedical Laboratory Scientist

Katherina Aguilera, Biomedical Laboratory Scientist

Martha Kihlgren, Biomedical Laboratory Scientist

Lena Gabrielsson, Research Nurse

Maja Månsson, Research Nurse


Sophia Hober

Peter Nilsson

Uppsala Universitet:

Mia Phillipson

Sara Mangsbo

Mikael Åberg

Karolinska institutet / Public health agency of Sweden:

Jonas Klingström

Kim Blom

Anna Smed-Sörensen


Selected publications

Members and contact

Group leader

All members of the group