pandemic.The researchers say they have designed Covid-19 vaccines in ways that aim to make sure they fight off infections, rather than worsen them.The large, final-stage trials starting to get under way will look for signs of rare side effects like the ones that arose for vaccines for dengue and other respiratory conditions, including other coronaviruses.
The rare complication, known as disease enhancement because it worsens the disease the vaccine is supposed to protect against, is a concern for vaccine research generally.“I think it’s important that we do rapid vaccine development, but I also think it’s important we do it safely," said Dr Barney Graham, deputy director of the vaccine research center at the National Institute of Allergy.