I am not a biology people. But this question has been bothering me for months.

I read the news that, even if an effective vaccine (for Covid-19) successfully created, the transport of the vaccine and its acceptance might still be a big problem; some vaccine need to be kept at extremely low temperature prior to using.

But then, what if the vaccine could cause one recipient to fall sick and the recipient spreads the mild disease to other people? This might sound bad, but then the community will develop immunity against the notorious Covid far much faster, more effectively and possibly free of charge for most of us. Instead of injecting the recipients one by one, just spread the vaccine like how Covid-19 spread.

Maybe the vaccine contains only part of the virus but not living virus, but considering those infected by mild cowpox will develop immunity against small pox, can't we just synthesize the cowpox-analogue for Covid-19? (Cowpox might not be spread through air, or from people to people, I am just saying, use highly contagious living virus that cause mild symptoms as vaccine)

Or is it because deliberately spreading viruses might be labelled as immoral so no one attempted this?

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    $\begingroup$ Hello. This may interest you. This question explains how the vaccines for Covid. Also note covid vaccines are not attenuated viruses. Also think about this - you have no control on the dosage each person will receive once you release a virus into the air. That does not sound ethical and healthy. $\endgroup$
    – Roni Saiba
    Commented Dec 8, 2020 at 13:47
  • $\begingroup$ I’m voting to close this question because it is primarily a medical question and so would be more appropriate on Medical Sciences, but please do not crosspost, instead request migration. ——— Please also take the tour and then go through the help center pages starting with How to Ask questions effectively on this site. Thanks! 😊 $\endgroup$
    – tyersome
    Commented Dec 8, 2020 at 19:32
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    $\begingroup$ I don't see how this is a medical question. However, it is poorly phrased and displays some misconceptions. $\endgroup$
    – KaPy3141
    Commented Dec 9, 2020 at 15:48

1 Answer 1


First: This is ethically completely out of question. Then: You could of course think about a attenuated virus, but these are designed to not spread like the disease, as they might mutate back and cause problems. This was a problem with the oral polio vaccine which is not used anymore for this reason.

This virus would need a higher transmissibility than the original virus to outcompete its spread. Creating a virus that spreads more easily but is less dangerous always harbours the danger that this virus mutates into something ways more dangerous than the original SARS-CoV-2 virus. Would you want to risk this? Also: We barely know the long-term consequences of COVID, what about another virus?

So, no, this is not a possible way.

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    $\begingroup$ Live attenuated poliovirus vaccines are still in use in various parts of the world. And yes, I agree it is an ethical concern, resulting in (rare) polio cases from vaccine derived polioviruses, particularly in immunodeficient children. $\endgroup$
    – De Novo
    Commented Dec 12, 2020 at 5:55
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    $\begingroup$ @user1136 Yes, to clarify, the ethical issue isn't that it's a live vaccine, it's that it is a live vaccine that is transmissible, and therefore exposes people who (a) haven't consented to receive the vaccine and (b) may be harmed by the vaccine (e.g., those with certain immunodeficiencies). For modern vaccines, transmissibility is only an issue with certain oral poliovirus vaccines. $\endgroup$
    – De Novo
    Commented Dec 13, 2020 at 3:10

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