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Comment by anonytrary | Hacker News Reader

These vaccines do not prevent spread! They decrease the probability of symptoms, and with any coronavirus, the main vector of spread is going to be through symptoms (coughing, sneezing, etc.). This means that if you are vaccinated, you will be less likely to spread the virus, but you must still wear a mask in order to protect those around you!

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That intuitively doesn't make sense for the fact that vaccines help produce antibodies which prevent the virus from spreading within the body and reproducing within the body. The spike protein is detected as something bad, and the body becomes furious and destroys the whole shebang, but not before binding to the spike protein as well and preventing it from infecting cells. If there's a lower viral load in the body, then it reduces the chance of spread (hint, because viral shedding is what causes spread across people).

Put away your exclamation points and have a glance at https://www.nytimes.com/interactive/2020/health/pfizer-biont...

Please don't spread misinformation. We don't yet have any reliable evidence on that one way or the other.

Source? This is ongoing research but the hypothesis is that vaccinated people spread the same rate as asymptonic COVID-19 carriers.

For example: https://globalnews-ca.cdn.ampproject.org/v/s/globalnews.ca/n...

Your link 404'd for me. Here is the direct link: https://globalnews.ca/news/7559408/health-matters-covid-19-v...

As I said, my contacts in the medical field have the same opinion as the article. It's "unknown" officially, but apparently people on HN don't know anyone in the field who is literally on the front lines researching this. The overwhelming opinion (articles aren't being written yet, expect some in a few weeks) is that the Pfizer vaccine does not actually prevent spread of the virus, only symptoms which decreases the probability of spread, but does not completely prevent spread.

So for the vaccination it seems that:

It does not prevent the virus from spreading It does not protect against certain variations that we are seeing like in South Africa

This means that the pandemic will still be there next winter some how. Likely not as bad as it is now. But it won't be over yet as a thread for societies. Remember most emerging/developing countries are not expected to receive vaccinations any time soon.

They'll be able to update the vaccination but many people will lose trust in them unfortunately

Means that our economies & currencies will be in trouble

Remote work will break through. After 2 years nobody is used to anything else anymore

Many people will permanently lose their job/business, but software companies will continue to do extremely well (although there will be some regulatory crack down on the largest companies)

Another option would be for Europe and the US to get people from Asia and Australia/NZ to teach us how to track and trace.

The article is asking the wrong question (Immune but infectious: Can someone vaccinated against COVID-19 still spread the virus?). The question is not whether or not, but to which degree. That is, how likely are they to spread the disease, how many people do they infect on average, how much virus do they shed...

The right term would be sterilization vaccine, at least thats what a epidemiologist recently called it, if I remember the term correctly?

This is not true, the Pfizer vaccine does not prevent you from carrying the virus and spreading it to others who do not have the vaccine. This is what a medical professional told me who was required to get the vaccine. Their entire department had to get vaccinated (Pfizer, not Moderna) and they are still required to wear masks for this very reason. Do your research.

> is what a medical professional told me.

> Do your research.

I don't mean this abrasively but, referring to an unknown third party for credibility and then telling people to do their research does not seem overly convincing to me.

Is my conclusion wrong? Best to err on the side of caution -- wear a mask, even if you got the vaccine. Period.

This is the right conclusion, but for the wrong reasons. A vaccine which induces antibodies should prevent spread because it will prevent your body from producing large quantities of the virus and hence prevent viral shedding.

The remaining factors which still require masks are the non-perfect efficiency (~5% of people will still get it), social factors (related to creating two classes of people; the immune and non-immune) and perhaps some others I forgot.

While I think I agree with you high-level, you and GP may be talking past each other when you use “prevent” when you more precisely mean “dramatically reduce [possibly to the point where you effectively prevent]”.

You're right. I also just found out about research (mentioned somewhere downthread) on differences between antibody expression in different tissue types (some IgA subtypes predominantly found in mucosa while other IgG types being dominantly systemic and/or in the lower respiratory system). The discussion there is on a whole other level of precision and points toward a mechanism which might indeed make it possible for vaccinated people to transmit the disease with some degree so it's not quite as clear cut as I presented it.

Though, intuitively, I'd still bet that vaccination will reduce viral shedding and the total load shedded, thus also reducing transmission.

Your tone is somewhat hostile.

As far as I can tell, we just don't know yet. Until we know, some preventative measures would be prudent.

So yes, the scenario you layout is possible. However, it is also possible that it does stop spread.

Even if it's unknown, my advice is still the correct advice, and this is what is recommended by medical professionals. Wear a mask after you got the vaccine.

You cannot say definitively “this is not true”. The advice to wear a mask after vaccination is still the best advice with the data we have, but you made a statement of fact that is currently unknown.

Why do you say not Moderna? Are they not equally effective?

Source?

Most other vaccines prevent spread. Why don't these?

It's been covered well in other comments, so read the whole thread, but basically it's expected that the vaccine would greatly decrease your ability to spread if not completely eliminate it. It's just pending hard data which is a bit complicated to study.

tl;dr per this Nature article, there's different type of antibody responses, intramuscular vaccines are better at inducing the flavor of antibody that works in the lower respiratory tract (which is excellent at attenuating disease severity) but not the kind that works in the upper respiratory tract. Also afaict, sars 2.0 reproduces in the upper respiratory tract, and it's this type of reproduction that allows for disease spread.

i'm not a virologist nor an immunologist but this is my understanding of the situation.

https://www.nature.com/articles/s41586-020-2798-3

> it is important to note that natural infection induces both mucosal antibody responses (secretory immunoglobulin A (IgA)) and systemic antibody responses (IgG). The upper respiratory tract is thought to be mainly protected by secretory IgA, whereas the lower respiratory tract is thought to be mainly protected by IgG27,28,29. Vaccines that are administered intramuscularly or intradermally induce mainly IgG, and no secretory IgA30. It is therefore possible that most vaccines currently in development induce disease-preventing or disease-attenuating immunity, but not necessarily sterilizing immunity (Fig. 2).

> The lower human respiratory tract is thought to be mostly protected by IgG (IgG1 is most prevalent), the main type of antibody in serum, which is transported into the lung. The upper respiratory tract is thought to be mostly protected by secretory IgA1 (sIgA1). a, Natural infection with respiratory viruses induces both a systemic immune response, dominated by IgG1, as well as a mucosal immune response in the upper respiratory tract that is dominated by sIgA1. This process can lead to sterilizing immunity for many respiratory viruses. b, Intramuscular or intradermal vaccination leads in many cases to a strong induction of serum IgG but not to an induction of mucosal IgA. Although some IgG can also be found on the mucosal surfaces of the upper respiratory tract, the lack of sIgA often leaves an individual vulnerable to infection of the upper respiratory tract. c, Intranasal vaccination can efficiently induce mucosal antibody responses, thereby potentially providing sterilizing immunity in the upper respiratory tract. However, systemic immune responses are often lower after this type of vaccination. Currently, all SARS-CoV-2 vaccine candidates in clinical development are administered intramuscularly, and very few of the more than 180 vaccine candidates in development are designed to induce mucosal immunity. Although mucosal immunity might not be required to protect from severe or even symptomatic disease, it could be required to achieve optimal protection from infection and onward transmission of SARS-CoV-2.

How about intranasal flu vaccines?

If we developed intranasal covid vaccines, would those also produce IgA antibodies?

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