COVID-19 Vaccines: What We Know About Side Effects and Vaccine Safety

The COVID-19 pandemic changed the world within a matter of months. As the virus spread internationally in early 2020, researchers worked at unprecedented speed to develop vaccines that could reduce severe illness, hospitalization, and death.

More than five years of vaccination and safety monitoring have now provided scientists with a much larger body of evidence about the benefits and possible side effects of COVID-19 vaccines.

Some side effects are common and temporary, while a small number of rare but potentially serious adverse events have been identified. Understanding the difference is important when evaluating vaccine safety.

1/10 — A Look Back at COVID-19

In December 2019, health authorities reported a cluster of unusual respiratory illnesses in Wuhan, China. The disease, later named COVID-19, was caused by a previously unknown coronavirus called SARS-CoV-2.

The virus spread rapidly across international borders, eventually leading the World Health Organization to declare a global pandemic in March 2020.

The pandemic placed enormous pressure on hospitals, healthcare workers, governments, businesses, and families around the world.

2/10 — The First Cases in France

France reported its first confirmed COVID-19 cases in January 2020.

As infections increased, authorities introduced increasingly strict public-health measures to slow transmission and protect healthcare systems.

By March 2020, France entered a nationwide lockdown.

3/10 — Lockdowns and the Search for a Vaccine

On March 17, 2020, France introduced a nationwide lockdown.

Restrictions were gradually eased in the following months, although face coverings, social distancing, testing, and other measures remained important parts of the public-health response.

At the same time, researchers around the world were working on vaccines.

The unprecedented urgency led governments, universities, biotechnology companies, and pharmaceutical manufacturers to invest enormous resources into vaccine research and clinical trials.