The government implemented new processes to review laboratory processes and test all new vaccine shipments to resolve the issues and then restart production. In subsequent years Albert Sabin developed another polio vaccine. His vaccine uses a weakened version of the live virus and is given by mouth rather than by injection. It is difficult to generate interest in clinical trials of new vaccines because the Salk vaccine has already been approved in the United States. So Sabin conducted clinical trials in the Soviet Union and Czechoslovakia, testing the vaccine on more than 10,000 children.
The World Health Organization later verified the clinical trial norway phone number library results. This is important because of the political tension and international distrust during the Cold War. After validation, the Sabin vaccine was quickly found to be a good tool for mass vaccination because it is an oral droplet form. Millions of people have now been safely vaccinated against polio. Vaccine-induced polio is extremely rare. Both polio vaccines are considered very safe. Only the inactivated polio vaccine, the original Salk vaccine, is approved for use in the United States.
The risk of vaccine-induced polio from these vaccines is now zero. The oral polio vaccine Sabin vaccine is used in other parts of the world. These viruses use extremely weakened versions of the virus that may in rare cases cause actual polio infection. Although there are good reasons for using oral polio vaccines, the immunity they confer not only protects the individual but also prevents the spread of news about vaccine-induced polio, which is likely to contribute to vaccine hesitancy.