“Vaccines will be administered to thousands of people in clinical trials before being made widely available to the public. They will continue to be closely monitored after approval.”
Before a vaccine is made available to the public, it will be given to thousands of people to test whether it can safely prevent serious illness. After getting vaccinated, many people roll up their sleeves and get through the rest of the day without any problems. Some people may have a sore arm or feel tired or feel generally unwell after certain vaccinations. This is usually mild and short-lived, lasting 1 to 2 days.
Independent regulatory authorities will decide whether to approve a vaccine based on the balance between these adverse events and its protective effect against severe disease. All medical interventions, from cholesterol drugs to chemotherapy and surgery, have potential downsides that patients and clinicians must consider. Removing a brain tumor comes with risks, but doing nothing may be even worse.
The standards are particularly high for vaccines, as the entire population is vaccinated, including infants, vulnerable people and healthy people. That’s why clinical trials on healthy people are closely studied before experts give a new vaccine the green light.
But once millions of people are vaccinated after approval, rare problems may arise. This means that there is a 1 in 1 million chance of an event occurring that would not have been detected in a trial of 5,000 people. This is where “post-market surveillance” comes into play. Individuals and medical professionals can report suspicious symptoms to regulatory authorities. These may include a rash or dizziness immediately after vaccination, or less common health problems several weeks after vaccination.
Regulators look for patterns in these reports and consider plausible links between vaccination and the reported problem to determine whether the vaccine could be the cause. In some cases, the vaccine may be the culprit, leading regulators to suspend its use or limit advice on who it can be offered to. In other cases, vaccination may be unrelated to the suspected problem.
Related articles
Bridging the gap: A data-driven vision for life course immunization November 10, 2023
What does ChatGPT think about vaccines? March 24, 2023
