Can we develop vaccines that transmit from person to person by themselves?
The usual way to vaccinate is for a person to go to a medical facility and get a vaccination.
While a virus like SARS-CoV-2 can spread exponentially from an infected person to other persons, the vaccines against a virus have to be given in a linear way to each person individually by hand.
Put simply: An infected person can infect other persons — but a vaccinated person cannot vaccinate other persons.
This difference between exponential and linear spread/distribution can have important effects on the time-critical race between virus infections/variations/mutations versus virus vaccinations in the world.
What if we could design safe vaccines that can transmit themselves from a vaccinated person to others, vaccines that are infectious just like a virus, but are protecting persons by giving immunity?
Obviously, infectious, replicating, self-disseminating vaccines for humans, which could be based on the targeted viruses themselves, potentially pose immense risks that have to be averted with the highest safety. Designing such a vaccine virus could be one of the most challenging tasks for humanity.
But the chance to vaccinate exponentially/self-distributing could make it possible to win the race against dangerous viruses like SARS-CoV-2. It could make it possible to save humans which would otherwise not get a vaccine in time, especially in regions and groups without good production or distribution logistics, financial priority or societal privilege. This could become even more important in case vaccinations against new viruses or new virus variants become a constant, regular necessity.
In the discussion about the SARS-CoV-2 virus, there was talk about virus variants/mutations emerging evolutionary that are less dangerous to humans but still confer immunity against the virus. The idea here would be to develop harmless virus variants, ourselves, as humans. Some current vaccinations against the SARS-CoV-2 virus are based on viruses but without the ability to replicate or transmit from person to person, which in their cases is a good safety measure and not their aim.
The aim here would be to create a vaccine which can replicate and transmit from person to person without causing disease and harm but with bringing immunity. The most demanding task would be to ensure the safety of such a vaccine virus. For example, to make it impossible for the vaccine to infect tissues or cells in the human body which should not be infected; for instance to only stay in the throat or nose region to transmit, but still confer full immunity. The human immune system must be able to recognize motifs which protect from the dangerous virus while being in no danger from the vaccine. There also would have to be hard-coded measures by design to exclude the possibility that the vaccine evolutionarily gains escalating, harmful, disease-causing functions, or that it interacts harmfully with other viruses present at the same time or in the same person.
There has been a lot of reporting on virus laboratories working on gain-of-function with viruses. Can we develop a vaccine based on a virus that has lost its functions to cause harm but still transmits immunity from human to human? Is it possible or too far-fetched right now? Do we have knowledge and tools to be able to accomplish it? Is there any discussion and research available on this topic/idea/question?
