Could one be injected with an infinitesimal amount of Covid-19 viral particles, in a way that it would trigger an immune response long enough before the virus overran the body? Could it be injected into tissue that was far enough away from the lungs, so that some immunity could build up before the virus reached the lungs?

I am talking about something similar to variolation, which was a method used to control the spread of smallpox. Material from smallpox sores (pustules) was given to people who had never had smallpox. This was done either by scratching the material into the arm or inhaling it through the nose.

People usually went on to develop the symptoms associated with smallpox. However, fewer people died than if they had acquired smallpox naturally.

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    You're describing a vaccine, except in the case of a vaccine, one uses virus that is most often attenuated or inactivated. Unlike other SE sites, questions here require prior research - you may be able to ask a better question if you learn a bit about how vaccines work first.
    – Bryan Krause
    Mar 17, 2020 at 16:51
  • No, I am talking about an alternative to a vaccine that may not be coming for 1-3 years from now. I am familiar with how vaccines work. Mar 17, 2020 at 17:00
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    The time it takes to develop a vaccine is the time it takes to test it for safety and efficacy. The same would be required for your suggestion (which is also a vaccine, not an alternative to one), you don't get to skip the clock by working with live virus.
    – Bryan Krause
    Mar 17, 2020 at 17:09
  • Vaccine safety trials i.e. phase 1 have already commenced. Mar 17, 2020 at 18:16
  • The case fatality rate from variolation was said to be 5% which is higher than dying from getting the Covid-19 infection naturally Apr 15, 2020 at 0:34

2 Answers 2


What you're describing is a live-virus vaccine. The only live-virus vaccines ever used were the early smallpox vaccines, which carried a significant risk of causing the disease rather than building immunity. Even attenuated vaccines (using a live but weakened form of the virus) can cause disease; most cases of polio these days are caused by the oral polio vaccine. Vaccines using inactivated viruses or virus fragments are strongly preferred.


This isn't really an answer since you have one already accepted but it postulates one possibility, noting that we are really in an evidence free zone. If the mods think it's unacceptable they can delete it.

The historical case fatality rate from variolation was 5%. The case fatality rate from smallpox was on average 30%. So, let's say approximately 15% of people using variolation got smallpox of whom 30% died to give us the case fatality rate of 5% from variolation.

Now variolation was pretty crude. Now the experts think that the inoculum needed to cause COVID-19 is about a few hundred - few 1000s of virions. So applying the dose is going to be hit and miss. Given that the skin isn't thought to be a major portal of infection, and the virus attacks monocytes and probably very little else in the skin, it may not be effective at all.

But let's say it's effective as smallpox, and we then get 15% of people who go on to develop clinical COVID-19. So, that's 15% of the population of the USA 328M which is 49M who get COVID-19 from your "vaccine" Assuming a case fatality rate of 1%, that's 492,000 deaths. But these people are going to infect other people as well so you're still going to end up with 49M infected people which is more than you have now in the USA.




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