Janssen vaccine is vector based, not mRNA like Pfizer Comirnaty or Moderna.
Although vaccinated people can be infected and even spread the virus, the disease is usually mild, amount of infectious virus and the time they are infectious is much smaller. And that is no speciality of covid immunizations, other vaccines like measles or influenza also don't prevent infection, but aim to prevent the disease.
The "not fully tested" meme is nonsense, many hundred million people have been vaccinated in the meantime, the safety profile is known.
Regarding long time effects beside immunity of vaccines, this interview https://lexfridman.com/vincent-racaniello/ goes into some detail. TLDL: there is nothing to expect/fear.
> Although vaccinated people can be infected and even spread the virus, the disease is usually mild, amount of infectious virus and the time they are infectious is much smaller.
I confess I haven't watched that video yet, but I believe there are not any studies that claim that "amount of infectious virus and the time they are infectious is much smaller". But I will watch it later and see if something new came up. I claim this because not long ago, our prime minister was infected after being fully vaccinated and had to be at home for 10 days before coming back to work.
Like I said, I am healthy and can work from home, so I have the luxury of waiting a little while to make my decision. After all, I am only affecting myself with this decision. A lot of people die from smoking/drinking alcohol as well, should we prevent them from getting it?
Part of the Israeli study showed that the viral count/load of breakthrough infections was not significantly lowered compared to non-breakthrough infections.
I know of one other study (can't find it at the moment though) that specifically looked not for CT value but if they are able to infect cells. The outcome was something like vaccinated people do replicate virus, but the spikes of those viruses are (mostly) deactivated by antibodies and therefore not as infectious as virus obtained from unvaccinated people. In rt-PCR tests you can't really distinguish infectious from deactivated virus.
Although vaccinated people can be infected and even spread the virus, the disease is usually mild, amount of infectious virus and the time they are infectious is much smaller. And that is no speciality of covid immunizations, other vaccines like measles or influenza also don't prevent infection, but aim to prevent the disease.
The "not fully tested" meme is nonsense, many hundred million people have been vaccinated in the meantime, the safety profile is known.
Regarding long time effects beside immunity of vaccines, this interview https://lexfridman.com/vincent-racaniello/ goes into some detail. TLDL: there is nothing to expect/fear.