Yes, I mean sterilizing immunity. Most likely having had Covid-19 will give you a partial immunity to disease.
There are highly effective vaccines that do not provide sterilizing immunity. I.e. they allow the pathogen to spread for a while, but enable the immune system to arrest the infection before the actual illness sets in.
So somebody who has had it once will become sick, will spread it, but will suffer a much milder form of the disease themselves.
Somebody like that would also have less (and in best case negligible) virus reproduction and therefore much lower viral loads in their upper respiratory system. That means less viral shedding and therefore less chance of infecting anybody else.
How would that be studied? Every living human being today, over one year of age, has had previous infections with other Coronaviruses. What's the control group?
This is where I got it from.
Immune cells for common cold may recognize SARS-CoV-2
Obviously there are still many known unknowns and unknown unknowns with this virus. But only ~15% of colds are due to coronaviruses, and it seems you need to have been infected with a strain that is genetically close to SARS-CoV-2 to have significant cross-immunity. That said, of course many people will have had such an infection. But that may explain why so many people are asymptomatic or mildly symptomatic while others, some of them young healthy people get seriously ill and sometimes, like
this student, even die.
Thanks to idiot meddling in testing procedures by Trump (or rather his CDC appointee) the American numbers mean nothing any longer.
Why? They seem realistic to me. Certainly more realistic than
for example Spain.
But the case numbers going up or down... we don't actually know. The other Coronaviruses are seasonal. Meaning that they die out in summer, and come back in winter. Even on the equator. We have no idea why this happens. It baffles science still. It's going to take years before we understand the ins and outs of Covid-19 spread.
It seems that
superspreader events are key. I.e. transmission is highly inconsistent. As far as seasonality, it is really weird. SARS-CoV-2 exploded down south in the Summer. Southern US gets really hot and most people flee for air conditioned indoor spaces, where the virus has easier time spreading. Fall is really pleasant around here, when it's not raining, so I expect more people to spend time outside.
Based on what I've heard/read, when the vaccine arrives, everybody will need to get boosted once ever two months. And this will be ongoing for more than a year. Since the idiotic anti-vaxxers will keep Covid-19 in circulation it might take many years of us having to do this. Chances are that the situation now is a permament situation, even with a vaccine.
There are many vaccine candidates. We shall see what the first approved vaccine requires as far as boosting and how effective it is. But yeah, idiot antivaxxers are a real problem.
