Covid-19: Natural vs. Vaccine Immunity

May 10, 2021: The World Health Organization published a Scientific Brief, with the following key messages:

  1. Within 4 weeks following infection, 90-99% of those infected develop neutralizing antibodies
  2. In most people, immunity remains robust against reinfection for at least 6-8 months (that is the longest followup period so far)
  3. Besides targeting the spike protein, natural immunity’s cellular immunity also targets other viral proteins
  4. Protection is still not well understood

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July 20, 2021: Cohen et al in the journal Cell Reports:  Longitudinal analysis shows durable and broad immune memory after SARS-CoV-2 infection with persisting antibody responses and memory B and T cells

  1. Most recovered Covid-19 patients mount broad, durable immunity after infection
  2. Neutralizing antibodies show a bi-phasic decay with half-lives of more than 200 days
  3. Spike IgG+ memory B cells increase and persist post-infection
  4. Durable polyfunctional CD4 and CD8 T cells recognize distinct viral epitope regions.

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April 20, 2021: Ivanova et al, in MedRxiv: Discrete immune response signature to SARS-CoV-2 mRNA vaccination versus infection

  1. There was a dramatic upregulation of interferon signaling (IFN) in the patients but not in the vaccinated subjects.
  2. Anti-NC antibodies wre only detectec in patients, not in vaccinated subjects.
  3. IgG antibody levels remained high for at least 7 weeks after the first vaccine dose, but IgA antibody titers declined steadily beginning 1 week after the second vaccine dose.
  4. A striking expansion of circulating plasmablasts were observed in patients, but not after vaccination.
  5. Plasmablasts for genes involving IL-6 receptor signaling were enriched for both.
  6. Infection potently induced IFN responses, not observed in the vaccinated subjects.
  7. Cytotoxic CD4 T cells were observed in patients but were absent in vaccinated subjects.

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