//Long term immunity, looking good

Long term immunity, looking good

Immunological memory to SARS-CoV-2 assessed for greater than six months after infection

(16th November, Institute for Immunology CA, and University of California)

https://www.biorxiv.org/content/10.1101/2020.11.15.383323v1

Humans make:

SARS-CoV-2-specific antibodies

CD4+ T cells (helpers)

CD8+ T cells (killers)

Memory B cells

Neutralizing antibodies have generally not correlated with lessened COVID-19 disease severity

Passive prophylactic antibodies limits disease in animals

Less so after infection

Clinical hepatitis is prevented by vaccine-elicited immune memory even in the absence of circulating antibodies

Six months or more is usually required to ascertain the durability of immune memory

Cross-sectional study

N = 185

41 cases, more than 6 months

Recovered COVID-19 cases

43% male, 57% female

Mild, moderate, and severe COVID-19 cases

Multiple sites throughout the United States

92% of subjects were never hospitalized

7% of subjects were hospitalized

97% symptomatic

Results, B cells

Spike IgG was relatively stable over 6+ months

Spike-specific memory B cells were more abundant at 6 months than at 1 month…

detected in almost all COVID-19 cases

No apparent half-life at 5+ months post-infection

Smallpox vaccine, 60+ years

Influenza infection, 90 years

Results, T cells

SARS-CoV-2-specific CD4+ T cells and CD8+ T cells declined with a half-life of 3-5 months

Decay of circulating SARS-CoV-2- specific CD8+ T cell is consistent with what has been reported for another acute virus

Smallpox also uses CD4+ T cells, t1/2 of ~10 years

T cell memory might reach a more stable plateau, or slower decay phase, later than the first 6 months post-infection.

Each component of SARS-CoV-2 immune memory exhibited distinct kinetics

Immunity and reinfection

Memory B and T cell responses can take 3-5 days to successfully respond to an infection

SARS-CoV T cells 17 years after the initial infection

SARS-CoV, MERS-CoV, and SARS-CoV-2 are all betacoronaviruses

https://www.cell.com/immunity/pdf/S1074-7613(20)30312-5.pdf

SARS-CoV-2 is most similar to SARS-CoV-1

Followed by MERS-CoV (2012)

https://www.medrxiv.org/content/10.1101/2020.04.14.20065771v1.full.pdf

It doesn’t matter that we were all doing social distancing, it doesn’t matter that I’m fit as a butcher’s dog, feel great – so many people do in my circumstances.

And actually it doesn’t matter that I’ve had the disease and I’m bursting with antibodies.

We’ve got to interrupt the spread of the disease…

and one of the ways we can do that now is by self isolating for 14 days when contacted by Test and Trace.