Vaccine won't stop infection?

[PastTense]

@puzzlegal

Although… thanks to the magic of the internet and the international nature of science, most of the vaccines that might be available in the US are likely to be available in other nations, as well.

Eventually, but not immediately. Countries, particularly the U.S., have been making deals to buy up the first several months worth of production.

[Sunny_Daze]

Having worked in pharmaceutical research, I can tell you that the timeframes for testing allowed here do not allow for sufficient analysis of prevention. In fact, I am skeptical about the long-term efficacy of any of these, because it’s simply too fast to analyze it. I really believe that at-risk populations would be foolish to take these vaccines without more time in the field.

[puzzlegal]

Based on people catching colds more than once, I’m guessing the covid vaccines WON’T have long-term effectiveness. That doesn’t mean aren’t worth getting. It just means that they might be like flu, something you have to keep doing.

[Sunny_Daze]

I definitely believe the vaccines will eventually be worth getting. I just don’t believe that at risk people should rush to get them. Another 6 months and I’ll start feeling more confident in efficacy and safety.

[Irishman]

They are now saying antibody counts start dropping after 3 months. That’s a hell of a lot worse than the flu. Do you see quarterly immunizations as something people will get on board for?

[puzzlegal]

The issue with flu isn’t actually that we lose our immunity, it’s that the flu virus mutates very quickly. This one seems to mutate somewhat slowly, fwiw.

There are a couple of possible ways a vaccine might work:

• It might engender longer-lasting immunity than a mild case of covid
• It might be really easy to take – think an oral vaccine
• It might provide “good enough” protection for a year, even if it only provides full protection for a few months.

[DSeid]

@puzzlegal

Based on people catching colds more than once, I’m guessing the covid vaccines WON’T have long-term effectiveness.

There are many viruses, even several hCoVs, that cause common cold symptoms, HCoVs are estimated to be about 15% of the common cold. Catching several common colds, even in a single season, informs little.

@Irishman

They are now saying antibody counts start dropping after 3 months.

“They” are always saying something.

FWIW there were two articles published in recent days, one in Nature that followed 65 individuals’ antibody responses for up to 94 days. These had been 59 individuals admitted to the hospital and six healthcare workers there. That study found that

the kinetics of the antibody response in SARS-CoV-2 infection is typical of an acute viral infection14,22,23,24. The peak in neutralizing antibodies arises due to a rapid production of short-lived plasmablasts30 that secrete high titres of antibodies; this is subsequently followed by a decline in virus-specific antibodies as these cells die.

The bigger and longer term study was published in Science

Robust neutralizing antibodies to SARS-CoV-2 infection persist for months
… the vast majority of infected individuals with mild-to-moderate COVID-19 experience robust IgG antibody responses against the viral spike protein, based on a dataset of 30,082 individuals screened at Mount Sinai Health System in New York City. We also show that titers are relatively stable for at least a period approximating 5 months and that anti-spike binding titers significantly correlate with neutralization of authentic SARS-CoV-2. Our data suggests that more than 90% of seroconverters make detectible neutralizing antibody responses. These titers remain relatively stable for several months after infection.

That’s what “they” are now saying. Unclear still about T-cell responses, strength against infection, and whether any immunization will work similarly.
.
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Antibody level persistence with influenza and influenza immunization is quagmire that I’ll avoid stepping into much (with August not recommended most years because protection might wane before the season is over, but before October ends advised to be sure of having protection in time), but this is interesting: influenza immunization MAY protect some against COVID-19.
https://www.medrxiv.org/content/10.1101/2020.10.14.20212498v1

[casdave]

Anti-bodies are only one part of the immune response, not all vaccines ensure a long term antibody count and this is not necessarily needed.

[puzzlegal]

@DSeid

There are many viruses, even several hCoVs, that cause common cold symptoms, HCoVs are estimated to be about 15% of the common cold. Catching several common colds, even in a single season, informs little.

I don’t have the cites handy, but I’ve seen two studies showing that the same person can catch the same corona virus repeatedly. I thought I’d posted one of them here previously…

Anyway, in one study a subsequent infection wasn’t as serious (maybe the person tested positive but didn’t really have a cold) and in the other at least one person got sick a second time in 3 months from the same corona virus. (One of the ones that can cause ‘a cold’)

So I’m not just taking about people catching multiple colds in a winter.

I’m dealing with a family medical crisis that i might want about in some other thread, so i doubt I’ll chase down those citations today. My recollection is that at least one of them was fairly hard to Google, despite being published in a journal I’d heard of. And at least one of the studies was done in NYC. Sigh.

[puzzlegal]

And then we’ve had several recent reports of people catching covid 19 more than once. There have been suggestions it happens since the start. But it can only be proven if they happen to sequence both stains so they can prove the second is a new infection, and not a recurrence of the initial infection. But just, “it can recur” suggests that many people don’t develop strong immunity from natural infection.

[DSeid]

@puzzlegal - not to worry. I (for reasons other than yours I am sure) am personally spending very little time in this particular forum anymore myself.

Here, for your interest, is a recent review of the various studies on antibody-mediated immunity to the other hCoVs, for however much into the weeds you want to get. Even with the same specific hCoV the data can get conflictual. The short version is that antibody levels stay high for a long time with MERS and SARS and less long for the endemic ones. Specific to the reinfection risk after infection with the common cold causing hCoVs there is this bit:

Several studies exposed volunteers to two viral challenges, some months apart. Reed 9 rechallenged six volunteers who had been experimentally infected with HCoV-229E 8–12 months previously9. On the first challenge, all six developed symptoms and detectable viruses, and five of six experienced a significant rise in titer. In the second, zero of six experienced illness, detectable virus or significant rise in titer. Callow et al.8 rechallenged volunteers with the same dose of HCoV-229E, 1 year apart. Of nine volunteers who were infected in the first exposure, 6 (67%) were infected in the second exposure. However, none of these individuals developed respiratory illness symptoms and they experienced a mean duration of detectable virus of 2 days compared to a mean of 5.6 in the initial challenge. Of note, these experimental doses may differ from the amounts of virus that people are exposed to in natural infections.

Clearly though SARS-CoV2 is neither one of the endemic common cold causing hCoVs or MERS or SARS. Probably somewhere between. This line in that article is the bottom line there:

Modeling studies will be crucial to answer these questions, but they will rely on an understanding of immune responses to SARS-CoV-2 and interactions with other coronaviruses to make relevant predictions. Analysis of datasets, specifically of serosurveys, needs to account for the kinetics of waning immunity and effects of imperfect assays to draw meaningful inferences.

As to “several recent reports of people catching covid 19 more than once” … I don’t think any one with any actual knowledge who has ever thought that all infected with SARS-CoV-2 would fully protected nor expected that whatever level of protection that did occur would stay the same level forever. My WAG is that in an absolute sense there are many who have been reinfected already, some of whom had undiagnosed initial infections and some of whom had asymptomatic to very mild second infections. But many in an absolute numbers sense may still be very very few in a relative sense, a very tiny percent of the huge number of infections that have occurred.

Relevant to this thread, if a vaccine protects from infection half of the time and decreases risk of severe infection significantly in many of those who still get infected, it would be considered a solid success.

At least that is what they say …

[puzzlegal]

@DSeid

Relevant to this thread, if a vaccine protects from infection half of the time and decreases risk of severe infection significantly in many of those who still get infected, it would be considered a solid success.

I certainly would consider that a major success. And I’d want to get that vaccine, unless a better one was available.

Everything you say is consistent with what I’ve seen. Also, people who have a more serious case of covid seem to show more persistent antibodies. Which suggests that a well designed vaccine might give better protection than a mild natural case.