From a piece by Australian epidemiologist Adrian Enterman claiming the vaccine won’t mean a safe return to international travel:
Let’s take the Pfizer/BioNTech vaccine as an example. They have reported the efficacy of their mRNA vaccine to be 95% in preventing symptomatic Covid-19, having tested it on around half of the 43,000 participants in their phase 3 trial (the other half received a placebo).
… However, the study hasn’t officially reported the efficacy of the vaccine against becoming infected, as opposed to displaying symptoms. While it’s encouraging to know a vaccine stops people getting sick, this point is important because if people can still become infected with SARS-CoV-2 (the virus that causes Covid-19), they may still be able to spread it.
So the Pfizer vaccine still allows people to become infected and spread the disease; they’re simply asymptomatic?
If so, I have other questions, but let’s start there.
They don’t know yet. This guy is just saying they haven’t proved vaccinated people aren’t infectious.
Making you be asymptomatic or very mild symptoms is used as the mark of a successful vaccine because that’s a more readily thing to test. How infectious people are is something that akes more time and effort to figure. Generally though, a vaccine that helps well with symptoms is probably good for lowering infectiousness.
I posed this exact question to an epidemiologist I follow on social media. She says they just don’t know yet. They also don’t know how long, if it confers immunity, that it will confer immunity. They are saying what President Elect Biden has been saying, we will need to continue in masks and social distancing for now.
The way the “questions” in the thread title and OP are framed, they are drawing a conclusion that is plainly not stated in the very thing that she quoted and bolded. In the current environment, in my opinion OP should be doing better than starting a thread where the thread title could be construed as a rhetorical question that is misinformation about the vaccine.
Well, I’d cut them some slack because as yet it’s not misinformation. It is a legitimate concern. Especially considering how asymptomatic people seem to be a contagion concern with this virus.
I apologize. The thread title should have been something more like: “Does lifesaving COVID vaccine make us asymptomatic carriers?” Or maybe you have a better way of phrasing it. If so, I’d be happy to request a title change. It certainly was NOT intended “to be construed as a rhetorical question that is misinformation about the vaccine.” My post should also have been worded better. Considering that and all the anti-science, anti-vaxx bullshit out there, it’s not surprising you drew the conclusion you did. In fact, I’ve been a strong proponent of safety measures and COVID vaccination, as my previous posts in QZ show. Not that I expect anyone to keep track. I’m distressed, though, to think I came off otherwise.
However, my questions–quotation marks unnecessary–came from a sincere desire to have my ignorance fought. People who are vaccinated against measles, I’d understood, are much less likely to spread the measles virus than the unvaccinated. I’d assumed that the COVID vaccine would work the same way; hence my confusion.
I’m not blaming the article in my OP for my ignorance or confusion, but I find this one clearer and wish it had come out before I posted:
Here’s what the studies don’t yet show. They haven’t looked at whether the vaccine prevents someone from carrying Covid-19 and spreading it to others. It’s possible that someone could get the vaccine but could still be an asymptomatic carrier. They may not show symptoms, but they have the virus in their nasal passageway so that if they’re speaking, breathing, sneezing and so on, they can still transmit it to others.
Thanks to all who fought my ignorance. I remain as strongly committed to vaccination as I’ve been all along. I don’t think posts can be removed, but if that’s changed with the move here, I’ll gladly request that.
Does any existing vaccine prevent virus transmission?
Maybe I’m misunderstanding what vaccines were meant to do … but I always thought of it as something that purely benefits the person getting vaccinated in the event of an infection. Although, logically … a person whose immune system beats back an infection should shed less virus and for a shorter time than someone with a full-blown infection and obvious symptoms.
Is it conclusively known one way or the other that, say, the flu vaccine has an effect of any kind on influenza transmission? Measles? Rubella? Chicken Pox? And so on.
Yes. The greatest level of protection, when an infection cannot take hold at all, is called sterilizing immunity.
Many vaccines are primarily intended to prevent disease and do not necessarily protect against infection. Some vaccines protect against infection as well. Hepatitis A vaccine has been shown to be equally efficacious (over 90% protection) against symptomatic disease and asymptomatic infections.26 Complete prevention of persistent vaccine-type infection has been demonstrated for human papillomavirus (HPV) vaccine.27 Such protection is referred to as “sterilizing immunity”.
However, as you note, even without fully sterilizing immunity, somebody with an immune system primed to fight the virus is likely to shed less virus and for a shorter time. It’s not as thought the sensible null hypothesis here is that the COVID vaccines will probably only reduce symptoms and do nothing to prevent infection or transmission. It’s just that we have little data, and nothing is certain in biology.
If it didn’t, would herd (vaccine induced) immunity be a thing?
Why would we be pushing for everyone to get flu shots or measles shots in the name of herd immunity and protecting those that can’t get the vaccine? If getting a vaccine only prevented you from having symptoms but still allowed you to become infected and contagious? At that point, I’d think the only thing slowing down transmission would be the absence of certain symptoms (like coughing) would make you not fling a few less germs all over the place.
This is an honest question, only in the past few weeks have I heard of vaccines making you asymptomatic if you catch a virus as opposed to not being able to catch it in the first place.
ETA Riemann’s reply wasn’t there when I started typing this a while ago and got distracted. I’ll have to read up on sterilizing immunity, I’ve never heard of it. I’ll apparently also have to get a better understanding of the difference between disease and infection.
To the contrary, your response was probably more on point than mine, with the examples of flu & measles etc. Sterilizing immunity is the highest level of protection, but we certainly don’t need that level of total resistance to infection to reduce transmission sufficiently for herd immunity.
The idea is more that if you get the vaccine, you may get infected, meaning that COVID takes some foothold in your body, but you’ll neither show symptoms nor die from it. That’s a huge game-changer for the elderly and/or at-risk population.
I think the rest is just an acknowledgement that the research and/or trials to determine if the vaccines prevent virus transmission haven’t been done yet, so they don’t know.
I got that, my point was more about the idea that if I get the vaccine and the second dose, if applicable, and I wait a the mandatory amount of time and I’m in the percentage of people for whom it works etc, IOW, I’m ‘immune’, I still can’t walk into a nursing home full of unvaccinated people since I could still have it and give it to them.
That was what I was saying. This is new to me, I understand that if your asymptomatic, it’s not going to harm you, I just didn’t realize vaccines (some? all? a few?) worked not be preventing you from catching the illness, but they simply keep the symptoms at bay, but leave those around you vulnerable.
Whenever there’s a discussion about the order people should get the vaccine in, a lot of people will make the (kinda) joke that those that have been calling this a hoax, those that have been going out to bars and parties, those who refuse to wear a mask, those who have generally acted like nothing out of the ordinary is happening should be last to get it.
My reply was generally that I don’t have a problem with the concept (in theory, of course it’s not actually going to happen that way), but I’d suggest that those people actually get bumped to the front of the line. Since they’re the ones causing the most problems, might as well get them inoculated ASAP so they stop making everyone else sick. If it makes you feel better, consider them the guinea pigs. You can see how they do until it’s your turn.
Having said that, if the vaccine really only protects you and anyone else is as likely to get sick because of you as they were before you were vaccinated, then fuck’em, I’ve stayed home, I’ve worn a mask, I’ve done what I can, I’d like my FastPass please. (But I’m ‘essential’, so I should be sooner [relatively] sooner rather than later anyway).
You can’t get COVID from an mRNA vaccine. It doesn’t contain any live virus; if a person were to get the vax and then get COVID, they were already in the incubation phase or, unfortunately, be one of the people who doesn’t make antibodies.
A good illustration is the Ebola vaccine, which is also mRNA. A scientist explained it this way: If the Ebola virus was a hand, the vaccine would be part of a fingernail.
I’m not sure if this was meant for me or not, but I wasn’t suggesting getting covid from that vaccine, but the possibility that vaccine doesn’t prevent you from getting or transmitting covid, it just keeps you asymptomatic.
If that’s directed at the OP, the question wasn’t asking if you get it from the vaccine. The question was about whether the vaccine just protects you from disease, or whether it also protects you from asymptomatic infection, and concomitantly whether it reduces transmission.
If this epidemiologist’s take was contributory/informed by the official AAHMS report then there seem to be some conflicting takes on whether we can say “not yet shown to be likely to stop infection” or “not likely to stop infection”
The money quote is “Evidence from animal studies and emerging data from clinical trials indicates that while the vaccines currently in clinical trials have a good chance of preventing COVID-19 illness, they are less likely to completely prevent infection with the SARSCoV-2 virus.” and this links back to this paper in The Lancet which says
Challenge studies in vaccinated primates showed reductions in pathology, symptoms, and viral load in the lower respiratory tract,6,7 but failed to elicit sterilising immunity in the upper airways. Sterilising immunity in the upper airways has been claimed for one vaccine, but peer-reviewed publication of these data are awaited.
(my bolds)
I interpret that as meaning that there is actual preliminary evidence leaning towards “the vaccines won’t cause immunity” which is somewhat worse than “we don’t have evidence yet either way”
I think it’s a fair reading that these very preliminary data indicate that we are unlikely to get complete sterilizing immunity. But this is not a binary outcome, the question is the size of the effect. It’s unlikely to eliminate transmission completely, but is also unlikely to have no effect at all. There’s an obvious a priori likelihood that if a vaccine equips your body to stop the virus enough to make any infection asymptomatic, it will reduce the likelihood of transmission to at least to some degree. At the very least, we know that if vaccinated people are infected, they will not be coughing and sneezing.
But it behooves scientists and authorities to be very cautious and conservative on guidance, because most especially in the early stages when (a) few people are vaccinated and (b) we don’t have good data on transmission, we absolutely don’t want vaccinated people throwing caution to the wind and thinking they can now start kissing strangers on the street. We need to maintain common sense physical distancing measures for the time being.