The CDC page is meant to end an old discussion about a decades old cover up, by admitting some undisputed facts and leaving open the rest of the allegations. It started 1942 with the invention of Penicillin, that suppressed bacteria in the gut, that suppressed the polio virus, leading to an epidemic, leading to a rush for the first polio vaccine in the fifties, leading to errors, leading to cover ups until today. The first cover up was that the first vaccine caused additional cases of polio because it used a dead virus that was not so dead as expected. The vaccine was distributed AFTER it was discovered that the virus was not always dead. The second cover up was that the SV40 virus, that causes cancer in apes, was found in the second batch of vaccines. Researchers at that time were sure that SV40 can cause cancer in humans too, but they got no funding so that the virus-cancer connection is mostly forgotten now. Only the CIA got the funding to further research the virus, because they needed something to finally get Fidel Castro. We don't know if they succeeded in creating a silent and slow assassination weapon.