How do we know if COVID-19 vaccines are safe?

How do we know that COVID-19 vaccines are safe?

Scientists look for potential safety issues during the testing phase and remain vigilant as vaccination campaigns progress around the world. For now, the only serious warning that has come up is a rare risk of a serious allergic reaction.

Different types of coronavirus vaccines have been licensed, and side effects may differ between them, although there is more public data on vaccines that are developed in Western countries than in the rest of the world. There are also differences between the vaccination standards of the countries, and some allow to inoculate some in their last phase of trials with a large number of volunteers.

But in the United States, Britain and the European Union, regulators require that any vaccine be tested in tens of thousands of people before distribution. For the moment, the United States uses those of Pfizer-BioNTech and Moderna, and Great Britain and Europe have also given the green light to that of AstraZeneca and the University of Oxford.

The large studies of all three found that common side effects were minor and typical of the immune system’s reaction: arm pain, fever, and flu-like symptoms like fatigue, chills and headache.

But since extremely rare problems may not show up even in the largest trials, vaccines remain under control. The US and British governments and the European Medicines Agency track reports from healthcare workers and the public on possible side effects. In the United States, there is additional scrutiny that includes following insurer claims for potential warnings. In addition, those who receive the injection there can join a program that sends them messages to check if they notice any symptoms.

These controls turn out to be reassuring.

After receiving the injection, people are supposed to stay in the center for a time in case they develop a severe allergic reaction, called anaphylaxis. So far, these cases have been rare, with between 2 and 5 per million vaccines given in the first weeks of the US campaign, according to the Centers for Disease Control and Prevention (CDC). country.

Authorities expect to receive reports of health problems, and even deaths, that occur just by chance in the days or weeks after vaccination given the large number of people, including elderly with more delicate health, who are inoculated.

The deaths and other serious cases are being investigated to see if the vaccine played a role. The authorities consider the general state of health of the person and the frequency with which the problem occurs without the vaccine. With more than 52 million vaccines administered in the United States through mid-February, the CDC said it has not detected any patterns in deaths that indicate a safety concern.