Convalescent antibodies from COVID-19 last up to 18 months

Posted on by Jesse Santiano, M.D.

A study in Italy compared two groups of people. Both groups have recovered from COVID-19. One group (n=21) was vaccinated with two doses of the Pfizer-Biontech COVID vaccine, and the other group (n=19) did not.

Backgrounder: The SARS-CoV-2 virus has several proteins, including the spike and nucleocapsid protein (NCP). After a COVID-19 infection, antibodies (IgG) to both are produced. Meanwhile, the Pfizer COVID vaccine contains the instructions for the spike protein, and therefore after a Pfizer shot, only the antibodies to the spike protein are expected to increase.

All participants had an infection in March 2020 when the predominant type is the Wuhan.  Serial blood samples were collected at several time points.

Results

A. Unvaccinated convalescent antibodies last 18 months

The unvaccinated convalescent group continued to have anti-spike and anti-nucleocapsid antibodies up to 18 months and did not report any COVID-19 reinfection despite multiple waves of variant strains.

According to the authors, this study shows the longest duration of antibody presence after a COVID-19 infection in unvaccinated people.

Other studies showing the duration of antibody levels post COVID-19

  • Seven months [6]
  • Eight months [7]
  • Ten months [8]
  • Eleven [9]
  • Thirteen  [10]
  • Fourteen [11]

Antinucleocapsid antibodies protect by facilitating antibody-dependent cytotoxicity and the complement system.

B. The rapid rise and decline of vaccinated antibodies

The graphs below represent the antibody levels (IgG) developed after the vaccination (vertical blue line). Two patients dropped off the study (33),(36), which is why there is no red line after their shots.

Note the rapid and steep increase in the antibody levels after vaccination. The rise in the IgG averaged 161 times immediately after the shots, and however,  the rise is short-lived.

Dehgani-Mobaraki et al, 2022

The assignment of numbers to the study participants was random. That’s is why some numbers are missing in the figure above. Those missing numbers represent the unvaccinated.

 Thoughts about the study

In their discussion, the investigators mentioned that mRNA vaccination also produces another antibody aside from the anti-spike IgG, which is called an IgA. However, the IgA from the vaccination is produced in the blood.

SARS-CoV-2 infections elicit secretory IgAs present in the linings of the nose and throat. These secretory IgAs bind to the SARS-CoV-2 viruses before they attach to human cells and thus prevent infections. In contrast, vaccine-induced IgA floating in the blood does not prevent infection.

The rise in the anti-spike IgG after the COVID shots (161 times) may look protective against COVID-19, and that is true. However, several studies [2][3][4][5] have shown that some of the spike proteins produced after the shots go to the bloodstream and potentially incite an inflammatory and thrombotic response wherever they may go. Those studies are featured in the following articles.

Furthermore, the featured study [1] can only conclude up to 18 months because that is the duration of the study. Future antibody duration studies will probably show a longer duration.

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  6. Protective Antibodies against SARS-CoV-2 are the same in Convalescent and Vaccinated
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  14. Antibodies to COVID-19 can Exist in the Uninfected

References:

  1. Puya-Dehgani-Mobaraki et al. Long-Term Persistence of IgG Antibodies in recovered COVID-19 individuals at 18 months and the impact of two-dose BNT162b2 (Pfizer-BioNTech) mRNA vaccination on the antibody response.  medRxiv 2022.01.18.22269349; doi: https://doi.org/10.1101/2022.01.18.22269349
  2. Kowarz E, Krutzke L, Reis J, et al. “Vaccine-Induced Covid-19 Mimicry” Syndrome: Splice reactions within the SARS-CoV-2 Spike open reading frame result in Spike protein variants that may cause thromboembolic events in patients immunized with vector-based vaccines. Research Square; 2021. DOI: 10.21203/rs.3.rs-558954/v1.
  3. Lee LL, Chintalgattu V. Pericytes in the Heart. Adv Exp Med Biol. 2019;1122:187-210. doi: 10.1007/978-3-030-11093-2_11. PMID: 30937870.
  4. Ogata AF. et al. Circulating SARS-CoV-2 Vaccine Antigen Detected in the Plasma of mRNA-1273 Vaccine Recipients [published online ahead of print, 2021 May 20]. Clin Infect Dis. 2021;ciab465. doi:10.1093/CID/ciab465
  5. Bansal et al. Cutting Edge: Circulating Exosomes with COVID Spike Protein Are Induced by BNT162b2 (Pfizer–BioNTech) Vaccination before Development of Antibodies: A Novel Mechanism for Immune Activation by mRNA Vaccines. J Immunol November 15, 2021, 207 (10) 2405-2410
  6. Abu-Raddad LJ et al. SARS-CoV-2 antibody-positivity protects against reinfection for
    at least seven months with 95% efficacy. EClinicalMedicine. 2021 May;35:100861. doi:
    10.1016/j.eclinm.2021.100861. Epub 2021 Apr 28. PMID: 33937733; PMCID: PMC8079668. 
  7. Anand SP, Prévost J, Nayrac M, et al. Longitudinal analysis of humoral immunity against SARS-CoV-2 Spike in convalescent individuals up to 8 months post-symptom onset. Cell Rep Med. 2021;2(6):100290. doi:10.1016/j.xcrm.2021.100290 
  8. Egbert ER, Xiao S, Colantuoni E, et al. Durability of Spike Immunoglobin G Antibodies to SARS-CoV-2 Among Health Care Workers With Prior Infection. JAMA Netw
    Open. 2021;4(8):e2123256. doi:10.1001/jamanetworkopen.2021.23256 
  9. Turner JS, et al. SARS-CoV-2 infection induces long-lived bone marrow plasma cells in humans. Nature. 2021 Jul;595(7867):421-425. doi: 10.1038/s41586-021-03647-4. Epub 2021 May 24. PMID: 34030176. 
  10. Gallais F, et al.  Evolution of antibody responses up to 13 months after SARS-CoV-2
    infection and risk of reinfection. EBioMedicine. 2021 Sep;71:103561. doi:
    10.1016/j.ebiom.2021.103561. Epub 2021 Aug 27. PMID: 34455390; PMCID: PMC8390300. 
  11. Dehgani-Mobaraki P et al. Longitudinal observation of antibody responses for 14 months after SARS-CoV-2 infection. Clin Immunol. 2021 
    Sep;230:108814.  doi: 10.1016/j.clim.2021.108814. Epub 2021 Jul 31. PMID: 34343708; PMCID: PMC8325385.

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