Vaccinations have had various long-term effects attributed to them ("autism" really took off), most of which have been debunked. I found a good overview addressing the popular claims:I'm trying to think of a drug that has delayed long term side effects after just two doses.
In Germany, a large number of biased reports against vaccination have recently been published in all of the news media, and particularly on the internet. This paper discusses the safety profile of modern vaccines and their continuous surveillance and shows why the current criticism of vaccination on safety grounds is unjustified.
One of the issues that appear to remain unresolved is the Guillain-Barre-Syndrome, which is usually triggered by an infection (e.g. Covid-19), and since a vaccination is a mock infection, it might trigger the syndrome as well. This is also an issue with some Covid vaccines.
GBS has a severe acute phase and often comes with lesser enduring effects.The risk appears to be very small. So far, there have been 100 reports of the syndrome in people who had received the Johnson & Johnson vaccine. Nearly 13 million doses of the vaccine have been administered in the United States.
This is not the first vaccine that has been linked to Guillain-Barré, although the risk appears to be tiny. A large swine flu vaccination campaign in 1976 led to a small uptick in the incidence of syndrome; the vaccine caused roughly one extra case of Guillain-Barré for every 100,000 people vaccinated. The seasonal flu shot is associated with roughly one to two additional cases for every million vaccines administered.
“I think the data are pretty compelling that the flu vaccine causes Guillain-Barré syndrome, but it’s a very small risk,” said Daniel Salmon, the director of the Institute for Vaccine Safety at Johns Hopkins University.
Obviously you need to weigh that small risk against the risk of contracting Covid and the common long-term effects of that.
Also, that effect is not "delayed". Delayed long-term effects often involve cancer, but that typically requires a more enduring exposure?