Dynamics of T-cell Responses Following COVID-19 mRNA Vaccination and Breakthrough Infection in Older Adults

Main Article Content

Sneha Datwani
Rebecca Kalikawe
Francis Mwimanzi
Sarah Speckmaier
Richard Liang
Yurou Sang
Rachel Waterworth
Fatima Yaseen
Hope R. Lapointe
Evan Barad
Mari L. DeMarco
Daniel T. Holmes
Janet Simons
Julio S.G. Montaner
Marc G. Romney
Zabrina L. Brumme
Mark A. Brockman


Introduction: While older adults generally mount weaker antibody responses to a primary COVID-19 vaccine series, T-cell responses remain less well characterized in this population. We compared SARS-CoV-2 spike-specific T-cell responses after 2- and 3-dose COVID-19 mRNA vaccination and subsequent breakthrough infection in older and younger adults.

Methods: We quantified CD4+ and CD8+ T-cells reactive to overlapping peptides spanning the ancestral SARS-CoV-2 spike protein in 40 older adults (median age 79) and 50 younger health care workers (median age 39), all COVID-19 naive, using an activation-induced marker assay. T-cell responses were further assessed in 24 participants, including 8 older adults, who subsequently experienced their first SARS-CoV-2 breakthrough infection.

Results: A third COVID-19 mRNA vaccine dose significantly boosted spike-specific CD4+ and CD8+ T-cell frequencies to above 2-dose levels in older and younger adults. T-cell frequencies did not significantly differ between older and younger adults after either dose. Multivariable analyses adjusting for sociodemographic, health, and vaccine-related variables confirmed that older age was not associated with impaired cellular responses. Instead, the strongest predictors of CD4+ and CD8+ T-cell frequencies post-third-dose were their corresponding post-second-dose frequencies. Breakthrough infection significantly increased both CD4+ and CD8+ T-cell frequencies, to comparable levels in older and younger adults. Exploratory analyses revealed an association between HLA-A*02:03 and higher post-vaccination CD8+ T-cell frequencies, which may be attributable to numerous strong-binding HLA-A*02:03-specific CD8+ T-cell epitopes in the spike protein.

Conclusion: Older adults mount robust T-cell responses to 2- and 3-dose COVID-19 mRNA vaccination, which are further boosted following breakthrough infection. 


Download data is not yet available.

Article Details



1. Onder G, Rezza G, Brusaferro S. Case-Fatality Rate and Characteristics of Patients Dying in Relation to COVID-19 in Italy. JAMA. 2020;323(18):1775-6. doi: 10.1001/jama.2020.4683. PubMed PMID: 32203977.

2. Richardson S, Hirsch JS, Narasimhan M, Crawford JM, McGinn T, Davidson KW, the Northwell C-RC, Barnaby DP, Becker LB, Chelico JD, Cohen SL, Cookingham J, Coppa K, Diefenbach MA, Dominello AJ, Duer-Hefele J, Falzon L, Gitlin J, Hajizadeh N, Harvin TG, Hirschwerk DA, Kim EJ, Kozel ZM, Marrast LM, Mogavero JN, Osorio GA, Qiu M, Zanos TP. Presenting Characteristics, Comorbidities, and Outcomes Among 5700 Patients Hospitalized With COVID-19 in the New York City Area. JAMA. 2020;323(20):2052-9. doi: 10.1001/jama.2020.6775. PubMed PMID: 32320003; PMCID: PMC7177629.

3. Williamson EJ, Walker AJ, Bhaskaran K, Bacon S, Bates C, Morton CE, Curtis HJ, Mehrkar A, Evans D, Inglesby P, Cockburn J, McDonald HI, MacKenna B, Tomlinson L, Douglas IJ, Rentsch CT, Mathur R, Wong AYS, Grieve R, Harrison D, Forbes H, Schultze A, Croker R, Parry J, Hester F, Harper S, Perera R, Evans SJW, Smeeth L, Goldacre B. Factors associated with COVID-19-related death using OpenSAFELY. Nature. 2020;584(7821):430-6. Epub 20200708. doi: 10.1038/s41586-020-2521-4. PubMed PMID: 32640463; PMCID: PMC7611074.

4. Polack FP, Thomas SJ, Kitchin N, Absalon J, Gurtman A, Lockhart S, Perez JL, Perez Marc G, Moreira ED, Zerbini C, Bailey R, Swanson KA, Roychoudhury S, Koury K, Li P, Kalina WV, Cooper D, Frenck RW, Jr., Hammitt LL, Tureci O, Nell H, Schaefer A, Unal S, Tresnan DB, Mather S, Dormitzer PR, Sahin U, Jansen KU, Gruber WC, Group CCT. Safety and Efficacy of the BNT162b2 mRNA Covid-19 Vaccine. N Engl J Med. 2020;383(27):2603-15. Epub 20201210. doi: 10.1056/NEJMoa2034577. PubMed PMID: 33301246; PMCID: PMC7745181.

5. Goronzy JJ, Li G, Yang Z, Weyand CM. The janus head of T cell aging - autoimmunity and immunodeficiency. Front Immunol. 2013;4:131. Epub 20130604. doi: 10.3389/fimmu.2013.00131. PubMed PMID: 23761790; PMCID: PMC3671290.

6. Jefferson T, Rivetti D, Rivetti A, Rudin M, Di Pietrantonj C, Demicheli V. Efficacy and effectiveness of influenza vaccines in elderly people: a systematic review. Lancet. 2005;366(9492):1165-74. Epub 20050922. doi: 10.1016/S0140-6736(05)67339-4. PubMed PMID: 16198765.

7. Nichol KL, Nordin JD, Nelson DB, Mullooly JP, Hak E. Effectiveness of influenza vaccine in the community-dwelling elderly. N Engl J Med. 2007;357(14):1373-81. doi: 10.1056/NEJMoa070844. PubMed PMID: 17914038.

8. Goronzy JJ, Weyand CM. Understanding immunosenescence to improve responses to vaccines. Nat Immunol. 2013;14(5):428-36. Epub 20130418. doi: 10.1038/ni.2588. PubMed PMID: 23598398; PMCID: PMC4183346.

9. Goronzy JJ, Weyand CM. Mechanisms underlying T cell ageing. Nat Rev Immunol. 2019;19(9):573-83. Epub 20190611. doi: 10.1038/s41577-019-0180-1. PubMed PMID: 31186548; PMCID: PMC7584388.

10. Andrews N, Tessier E, Stowe J, Gower C, Kirsebom F, Simmons R, Gallagher E, Thelwall S, Groves N, Dabrera G, Myers R, Campbell CNJ, Amirthalingam G, Edmunds M, Zambon M, Brown K, Hopkins S, Chand M, Ladhani SN, Ramsay M, Lopez Bernal J. Duration of Protection against Mild and Severe Disease by Covid-19 Vaccines. N Engl J Med. 2022;386(4):340-50. Epub 20220112. doi: 10.1056/NEJMoa2115481. PubMed PMID: 35021002; PMCID: PMC8781262.

11. Collier DA, Ferreira I, Kotagiri P, Datir RP, Lim EY, Touizer E, Meng B, Abdullahi A, Collaboration C-NBC-, Elmer A, Kingston N, Graves B, Le Gresley E, Caputo D, Bergamaschi L, Smith KGC, Bradley JR, Ceron-Gutierrez L, Cortes-Acevedo P, Barcenas-Morales G, Linterman MA, McCoy LE, Davis C, Thomson E, Lyons PA, McKinney E, Doffinger R, Wills M, Gupta RK. Age-related immune response heterogeneity to SARS-CoV-2 vaccine BNT162b2. Nature. 2021;596(7872):417-22. Epub 20210630. doi: 10.1038/s41586-021-03739-1. PubMed PMID: 34192737; PMCID: PMC8373615.

12. Levin EG, Lustig Y, Cohen C, Fluss R, Indenbaum V, Amit S, Doolman R, Asraf K, Mendelson E, Ziv A, Rubin C, Freedman L, Kreiss Y, Regev-Yochay G. Waning Immune Humoral Response to BNT162b2 Covid-19 Vaccine over 6 Months. N Engl J Med. 2021;385(24):e84. Epub 20211006. doi: 10.1056/NEJMoa2114583. PubMed PMID: 34614326; PMCID: PMC8522797.

13. Palacios-Pedrero MA, Jansen JM, Blume C, Stanislawski N, Jonczyk R, Molle A, Hernandez MG, Kaiser FK, Jung K, Osterhaus A, Rimmelzwaan GF, Saletti G. Signs of immunosenescence correlate with poor outcome of mRNA COVID-19 vaccination in older adults. Nat Aging. 2022;2(10):896-905. Epub 20221014. doi: 10.1038/s43587-022-00292-y. PubMed PMID: 37118289; PMCID: PMC10154205.

14. Mwimanzi F, Lapointe HR, Cheung PK, Sang Y, Yaseen F, Kalikawe R, Datwani S, Burns L, Young L, Leung V, Ennis S, Brumme CJ, Montaner JSG, Dong W, Prystajecky N, Lowe CF, DeMarco ML, Holmes D, Simons J, Niikura M, Romney MG, Brumme ZL, Brockman MA. Impact of age and SARS-CoV-2 breakthrough infection on humoral immune responses after three doses of COVID-19 mRNA vaccine. Open Forum Infectious Diseases. 2023; Accepted, In Press.

15. Mwimanzi F, Lapointe HR, Cheung PK, Sang Y, Yaseen F, Umviligihozo G, Kalikawe R, Datwani S, Omondi FH, Burns L, Young L, Leung V, Agafitei O, Ennis S, Dong W, Basra S, Lim LY, Ng K, Pantophlet R, Brumme CJ, Montaner JSG, Prystajecky N, Lowe CF, DeMarco ML, Holmes DT, Simons J, Niikura M, Romney MG, Brumme ZL, Brockman MA. Older Adults Mount Less Durable Humoral Responses to Two Doses of COVID-19 mRNA Vaccine but Strong Initial Responses to a Third Dose. J Infect Dis. 2022;226(6):983-94. Epub 2022/05/12. doi: 10.1093/infdis/jiac199. PubMed PMID: 35543278; PMCID: PMC9129202.

16. US Food and Drug Administration. FDA Authorizes Booster Dose of Pfizer-BioNTech COVID-19 Vaccine for Certain Populations. fda.gov2021.

17. Bowman E. A CDC Panel Backs Booster Shots For Older Adults, A Step Toward Making Them Available. ‘National Public Radio, USA. 2021 23 Sept 2021.

18. Moss P. The T cell immune response against SARS-CoV-2. Nat Immunol. 2022;23(2):186-93. Epub 20220201. doi: 10.1038/s41590-021-01122-w. PubMed PMID: 35105982.

19. Painter MM, Mathew D, Goel RR, Apostolidis SA, Pattekar A, Kuthuru O, Baxter AE, Herati RS, Oldridge DA, Gouma S, Hicks P, Dysinger S, Lundgreen KA, Kuri-Cervantes L, Adamski S, Hicks A, Korte S, Giles JR, Weirick ME, McAllister CM, Dougherty J, Long S, D’Andrea K, Hamilton JT, Betts MR, Bates P, Hensley SE, Grifoni A, Weiskopf D, Sette A, Greenplate AR, Wherry EJ. Rapid induction of antigen-specific CD4(+) T cells is associated with coordinated humoral and cellular immunity to SARS-CoV-2 mRNA vaccination. Immunity. 2021;54(9):2133-42 e3. Epub 20210813. doi: 10.1016/j.immuni.2021.08.001. PubMed PMID: 34453880; PMCID: PMC8361141.

20. Sahin U, Muik A, Derhovanessian E, Vogler I, Kranz LM, Vormehr M, Baum A, Pascal K, Quandt J, Maurus D, Brachtendorf S, Lorks V, Sikorski J, Hilker R, Becker D, Eller AK, Grutzner J, Boesler C, Rosenbaum C, Kuhnle MC, Luxemburger U, Kemmer-Bruck A, Langer D, Bexon M, Bolte S, Kariko K, Palanche T, Fischer B, Schultz A, Shi PY, Fontes-Garfias C, Perez JL, Swanson KA, Loschko J, Scully IL, Cutler M, Kalina W, Kyratsous CA, Cooper D, Dormitzer PR, Jansen KU, Tureci O. COVID-19 vaccine BNT162b1 elicits human antibody and T(H)1 T cell responses. Nature. 2020;586(7830):594-9. Epub 20200930. doi: 10.1038/s41586-020-2814-7. PubMed PMID: 32998157.

21. Jo N, Hidaka Y, Kikuchi O, Fukahori M, Sawada T, Aoki M, Yamamoto M, Nagao M, Morita S, Nakajima TE, Muto M, Hamazaki Y. Impaired CD4(+) T cell response in older adults is associated with reduced immunogenicity and reactogenicity of mRNA COVID-19 vaccination. Nat Aging. 2023;3(1):82-92. Epub 20230112. doi: 10.1038/s43587-022-00343-4. PubMed PMID: 37118516; PMCID: PMC10154196.

22. Brockman MA, Mwimanzi F, Lapointe HR, Sang Y, Agafitei O, Cheung PK, Ennis S, Ng K, Basra S, Lim LY, Yaseen F, Young L, Umviligihozo G, Omondi FH, Kalikawe R, Burns L, Brumme CJ, Leung V, Montaner JSG, Holmes D, DeMarco ML, Simons J, Pantophlet R, Niikura M, Romney MG, Brumme ZL. Reduced Magnitude and Durability of Humoral Immune Responses to COVID-19 mRNA Vaccines Among Older Adults. J Infect Dis. 2022;225(7):1129-40. Epub 2021/12/11. doi: 10.1093/infdis/jiab592. PubMed PMID: 34888688; PMCID: PMC8689804.

23. Brumme ZL, Brumme CJ, Chui C, Mo T, Wynhoven B, Woods CK, Henrick BM, Hogg RS, Montaner JS, Harrigan PR. Effects of human leukocyte antigen class I genetic parameters on clinical outcomes and survival after initiation of highly active antiretroviral therapy. J Infect Dis. 2007;195(11):1694-704. Epub 20070424. doi: 10.1086/516789. PubMed PMID: 17471440.

24. Woods CK, Brumme CJ, Liu TF, Chui CK, Chu AL, Wynhoven B, Hall TA, Trevino C, Shafer RW, Harrigan PR. Automating HIV drug resistance genotyping with RECall, a freely accessible sequence analysis tool. J Clin Microbiol. 2012;50(6):1936-42. Epub 20120307. doi: 10.1128/JCM.06689-11. PubMed PMID: 22403431; PMCID: PMC3372133.

25. Reynisson B, Alvarez B, Paul S, Peters B, Nielsen M. NetMHCpan-4.1 and NetMHCIIpan-4.0: improved predictions of MHC antigen presentation by concurrent motif deconvolution and integration of MS MHC eluted ligand data. Nucleic Acids Res. 2020;48(W1):W449-W54. doi: 10.1093/nar/gkaa379. PubMed PMID: 32406916; PMCID: PMC7319546.

26. Storey JD, Tibshirani R. Statistical significance for genomewide studies. Proc Natl Acad Sci U S A. 2003;100(16):9440-5. Epub 20030725. doi: 10.1073/pnas.1530509100. PubMed PMID: 12883005; PMCID: PMC170937.

27. Skowronski DM, Febriani Y, Ouakki M, Setayeshgar S, El Adam S, Zou M, Talbot D, Prystajecky N, Tyson JR, Gilca R, Brousseau N, Deceuninck G, Galanis E, Fjell CD, Sbihi H, Fortin E, Barkati S, Sauvageau C, Naus M, Patrick DM, Henry B, Hoang LMN, De Wals P, Garenc C, Carignan A, Drolet M, Jassem AN, Sadarangani M, Brisson M, Krajden M, De Serres G. Two-Dose Severe Acute Respiratory Syndrome Coronavirus 2 Vaccine Effectiveness With Mixed Schedules and Extended Dosing Intervals: Test-Negative Design Studies From British Columbia and Quebec, Canada. Clin Infect Dis. 2022;75(11):1980-92. doi: 10.1093/cid/ciac290. PubMed PMID: 35438175; PMCID: PMC9047203.

28. Buchan SA, Seo CY, Johnson C, Alley S, Kwong JC, Nasreen S, Calzavara A, Lu D, Harris TM, Yu K, Wilson SE. Epidemiology of Myocarditis and Pericarditis Following mRNA Vaccination by Vaccine Product, Schedule, and Interdose Interval Among Adolescents and Adults in Ontario, Canada. JAMA Netw Open. 2022;5(6):e2218505. Epub 20220601. doi: 10.1001/jamanetworkopen.2022.18505. PubMed PMID: 35749115; PMCID: PMC9233237.

29. Organization WH. Interim recommendations for use of the Moderna mRNA-1273 vaccine against COVID-19. 2021 Updated 18 August 2022. Report No.

30. BC Centre for Disease Control. Weekly update on Variants of Concern 2022. Available from: http://www.bccdc.ca/health-info/diseases-conditions/covid-19/data.

31. Muller L, Andree M, Moskorz W, Drexler I, Walotka L, Grothmann R, Ptok J, Hillebrandt J, Ritchie A, Rabl D, Ostermann PN, Robitzsch R, Hauka S, Walker A, Menne C, Grutza R, Timm J, Adams O, Schaal H. Age-dependent Immune Response to the Biontech/Pfizer BNT162b2 Coronavirus Disease 2019 Vaccination. Clin Infect Dis. 2021;73(11):2065-72. Epub 2021/04/28. doi: 10.1093/cid/ciab381. PubMed PMID: 33906236; PMCID: PMC8135422.

32. Bose T, Pant N, Pinna NK, Bhar S, Dutta A, Mande SS. Does immune recognition of SARS-CoV2 epitopes vary between different ethnic groups? Virus Res. 2021;305:198579. Epub 20210921. doi: 10.1016/j.virusres.2021.198579. PubMed PMID: 34560183; PMCID: PMC8453877.

33. Rao V, Chandra N. In-silico study of influence of HLA heterogeneity on CTL responses across ethnicities to SARS-CoV-2. Hum Immunol. 2022;83(12):797-802. Epub 20221011. doi: 10.1016/j.humimm.2022.09.008. PubMed PMID: 36229378; PMCID: PMC9550298.

34. Bertinetto FE, Magistroni P, Mazzola GA, Costa C, Elena G, Alizzi S, Scozzari G, Migliore E, Galassi C, Ciccone G, Ricciardelli G, Scarmozzino A, Angelone L, Cassoni P, Cavallo R, Vaisitti T, Deaglio S, Amoroso A, Collaborative G. The humoral and cellular response to mRNA SARS-CoV-2 vaccine is influenced by HLA polymorphisms. HLA. 2023. Epub 20230403. doi: 10.1111/tan.15049. PubMed PMID: 37010080.

35. Srivastava A, Hollenbach JA. The immunogenetics of COVID-19. Immunogenetics. 2023;75(3):309-20. Epub 20221219. doi: 10.1007/s00251-022-01284-3. PubMed PMID: 36534127; PMCID: PMC9762652.

36. Sacco K, Castagnoli R, Vakkilainen S, Liu C, Delmonte OM, Oguz C, Kaplan IM, Alehashemi S, Burbelo PD, Bhuyan F, de Jesus AA, Dobbs K, Rosen LB, Cheng A, Shaw E, Vakkilainen MS, Pala F, Lack J, Zhang Y, Fink DL, Oikonomou V, Snow AL, Dalgard CL, Chen J, Sellers BA, Montealegre Sanchez GA, Barron K, Rey-Jurado E, Vial C, Poli MC, Licari A, Montagna D, Marseglia GL, Licciardi F, Ramenghi U, Discepolo V, Lo Vecchio A, Guarino A, Eisenstein EM, Imberti L, Sottini A, Biondi A, Mato S, Gerstbacher D, Truong M, Stack MA, Magliocco M, Bosticardo M, Kawai T, Danielson JJ, Hulett T, Askenazi M, Hu S, Group NIRtC, Chile MISCG, Pavia Pediatric C-G, Cohen JI, Su HC, Kuhns DB, Lionakis MS, Snyder TM, Holland SM, Goldbach-Mansky R, Tsang JS, Notarangelo LD. Immunopathological signatures in multisystem inflammatory syndrome in children and pediatric COVID-19. Nat Med. 2022;28(5):1050-62. Epub 20220217. doi: 10.1038/s41591-022-01724-3. PubMed PMID: 35177862; PMCID: PMC9119950.

37. Smith M, Abdesselem HB, Mullins M, Tan TM, Nel AJM, Al-Nesf MAY, Bensmail I, Majbour NK, Vaikath NN, Naik A, Ouararhni K, Mohamed-Ali V, Al-Maadheed M, Schell DT, Baros-Steyl SS, Anuar ND, Ismail NH, Morris PE, Mamat RNR, Rosli NSM, Anwar A, Ellan K, Zain RM, Burgers WA, Mayne ES, El-Agnaf OMA, Blackburn JM. Age, Disease Severity and Ethnicity Influence Humoral Responses in a Multi-Ethnic COVID-19 Cohort. Viruses. 2021;13(5). Epub 20210428. doi: 10.3390/v13050786. PubMed PMID: 33925055; PMCID: PMC8146997.

38. Martin CA, Nazareth J, Jarkhi A, Pan D, Das M, Logan N, Scott S, Bryant L, Abeywickrama N, Adeoye O, Ahmed A, Asif A, Bandi S, George N, Gohar M, Gray LJ, Kaszuba R, Mangwani J, Martin M, Moorthy A, Renals V, Teece L, Vail D, Khunti K, Moss P, Tattersall A, Hallis B, Otter AD, Rowe C, Willett BJ, Haldar P, Cooper A, Pareek M. Ethnic differences in cellular and humoral immune responses to SARS-CoV-2 vaccination in UK healthcare workers: a cross-sectional analysis. EClinicalMedicine. 2023;58:101926. Epub 20230404. doi: 10.1016/j.eclinm.2023.101926. PubMed PMID: 37034357; PMCID: PMC10071048.