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Comment by fspeech | Hacker News Reader

Antibody diversity is created through a process called hypervariation. It is basically a random generation process. We then filter out those that recognize markers produced by our own body. So each person's antibody will work differently in recognizing the virus, that is choosing what markers to bind to. Whatever antibody that works will go through a clonal multiplication that causes the B cells that produced the antibodies to replicate, conferring resistance to reinfection. So long as your choice of antibody does not happen to depend on the SNP (a seemingly small chance but we also don't know its function for the virus so hard to say) you will be resistant to both types.

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How come folks are saying you can get reinfected tho? Has there ever been a disease that the same strain can reinfect someone? Wouldn’t that imply they’d never recover?

The exact same way that people repeatedly catch the common coronavirus year after year. 2019's novel coronavirus is destined to end up being known as the "common cold" or coronavirus with time. All common colds are a coronavirus and newly discovered ones are novel. IOW there is no vaccine in the pipeline because there's never been a vaccine for the common cold.

https://www.who.int/health-topics/coronavirus

But you’re talking about mutations or other strains. My question is can the exact same virus reinfect a person?

I’d think you’d never clear it to begin with if that was the case.

> All common colds are a coronavirus and newly discovered ones are novel.

Technically not true - coronaviruses cause 15-30% of common colds. The most common cause of the common cold is rhinovirus (30-80%); coronavirus is next, followed by influenza (10-15%), adenovirus, and then other viruses like RSV. The rest of your comment is fairly likely IMHO, though.

I think there have been a few unverified reports of people catching the virus again. However these might be caused by false negative tests (viral load being lower during the time of testing), then they re-take the test when they have a higher viral load(?) and it comes back positive.

This is purely based on other comments I've read, I personally know nothing about viruses.

Some diseases have 2 phases (biphasic), so you get sick, recover somewhat, get sick again, often with different symptoms.

I've read in the press that corona virus might be biphasic, which is a big problem for an air-borne transmissable disease. In the jet age, quarantining potentially thousands or millions of passengers becomes expensive and disruptive when there's a week between phases.

Lyme disease is like that. First you get a bullseye rash and flu-like symtoms, it goes away, then later your organs are attacked.

https://en.wikipedia.org/wiki/Biphasic_disease

That's different than a chronic disease, where you never recover.

Why can’t the memory cells help for the second phase?

Shouldn’t the first phase act as a sort of vaccine?

I wonder if it's possible that the virus can take shelter in cells that are not exposed to the antibodies. Don't herpes viruses do something like that? People get chicken pox as a kid, and later get shingles.

Just to be clarify, B cells undergo somatic hypermutation while undergoing expansion after antigen recognition. On re-exposure, memory cells will be available to identify existing antigens and re-expand the B cells involved with attacking the viral particles.

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