COVID 19 Course Update: Immunity and Antibodies

 

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Antibody Review

IgM – first antibody on site binds to virus and begins the immune cascade

IgA – Principal antibody in secretions, mucosal surfaces

IgG – Main antibody response, persists longest after infection, immunity

 

Natural Immunity vs. Vaccine Induced Immunity CDC 9 State Study Oct 29, 2021

Followed hospitalized patients immune status 

  • 201,269 hospitalizations collected/9 states
  • Previous infection vs. fully vaccinated
  • 3 – 6 months window prior to data collection

Results:

  • Previous infection patients were 5.49 times more likely to end up in hospital than vaccinated patients.
  • Vaccination significantly improved protection from hospitalization.

 

Natural Immunity vs. Vaccine Induced Immunity Israel Study August 25, 2021

  • Three groups matched to time of vax/infection
  • 16,215 in each group

Group 1: SARS-CoV-2-naïve individuals who received a two-dose regimen of the BioNTech/Pfizer mRNA vaccine

  • 238 infections
  • 199 symptomatic
  • 8 hospitalizations
  • 0 death

Group 2: Previously infected individuals who have not been vaccinated

  • 19 infections
  • 8 symptomatic
  • 1 hospitalization
  • 0 deaths

Group 3: Previously infected individuals who received one dose BioNTech/Pfizer mRNA vaccine

  • Infection risk reduced by half over Group 2

 

Natural Immunity American Society of Microbiology Sept 2021 University of Michigan

Prior Infection Vs. Non-infection Prospective Study

  • 653 prospectively followed at 3 and 6 months
  • Prior infection demonstrated persistent Antibody levels at 3 and 6 months
  • Clinical outcomes
    • Control group – 15 cases
    • Prior infection group –  0 cases

 

COVID Infection Seroconversion Rates CDC Sept 2021

72 people with proven SARS COV-2 Infections

  • 2 persons (3%) reported no symptoms
  • 13 (18%) persons reported mild disease
  • 48 (67%) reported moderate disease
  • 9 (12%) reported severe disease

Follow-up antibody testing

  • 46 with detectable IgG, IgA at follow-up
  • 26 no IgG, IgA detected

 

Long Lasting Immunity After COVID Infection Nature May 2021

  • Serum Antibodies
    • Decline rapidly in first 4 months
    • Decline slower after 4 months
    • Detectable at 11 months
  • Plasma Cells – long term immunity component
    • COVID Spike protein Bone Marrow Plasma Cells (BMPC) present at 11 months
    • Resting Memory Circulating B Cells detected at 11 months
    • Long term immunity confirmed
  • Conclusions
    • Mild infection initiated robust immunity
    • Immunity proven at 11 months
    • Immunity likely to be life long

Lasting Immunity Found After Recovery From COVID-19      NIH Jan 26, 2021

Key Points

  • The immune systems of more than 95% of people who recovered from COVID-19 had durable memories of the virus up to eight months after infection.
  • The results provide hope that people receiving SARS-CoV-2 vaccines will develop similar lasting immune memories after vaccination.

 

Long Term B cell memory to SARS-CoV-2 spike and nucleocapsid proteins.  ScienceImmunology Dec 2020

Key Points-LongTerm Immunity – 282 days

  • 25 COVID Patients
    • Followed up to 282 days
    • 3 severe disease
    • 6 moderate disease
    • 16 mild disease
  • Early B Cell Memory appearance
    • Persistence up to 282 days – signifies immunity longevity
    • Long term immunity
    • Accurate test for immunity
  • IgG
    • Spike at 20 days
    • Gradual reduction over time represents a contraction of response not disappearance or weakening
    • Detectable at 240 days along with B memory cells

Study of Healthcare Workers Shows COVID-19 Immunity Lasts Many Months Dec 2020 Oxford University Dec 2020

Key Points

  • 12,219 Healthcare workers tested for COVID anti-spike IgG antibodies
    • 1246 COVID antibodies present
      • No infections over 6 months
    • 11,052 no antibodies
      • 89 symptomatic infections
      • 76 asymptomatic infections
  • Protection from reinfection for at least 6 months
  • Clinical Trial Reference CLICK HERE

Persistence and decay of human antibody responses to the receptor binding domain of SARS-CoV-2 spike protein in COVID-19 patients   Science Immunology Oct 2020

Hospitalized patients (343) compared with pre-COVID controls (1548)

  • Positive sero-conversion median      12 days
  • Antibody IgG at 3 months     99%
    • No decay at 3 months
  • IgA and IgM revert to undetectable    2.5 months

Conclusions:  IgG Antibody measurements are reliable to detecting past infection.  Persistence of IgG at 3 months without decay denotes at least short term immunity.

  

Persistence of serum and saliva antibody responses to SARS-CoV-2 spike antigens in COVID-19 patients  Science Immunology Oct 2020.

  • 439 patients serum testing
  • 128 patients saliva testing
  • Peak IgG 16 – 30 days
  • IgG stable at 115 days 
    • serum
    • saliva

Conclusion:  Stable IgG at 115 denotes at least short term immunity.  Saliva antibody testing may be as effective as serum testing for COVID 19 IgG avoid blood drawing and improving the scalability of antibody testing. 

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  • Immunity Nov 2021
  • Regeneron – April 2021
  • Variants – Aug 2021
  • Vaccines – April 2021
  • Pediatrics – Nov 2021
  • Air travel risk – Dec 2020
  • Antiviral treatments – Dec 2020
  • Surface contact transmission – July 2020

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