What is an mRNA vaccine?

mRNA stands for messenger RNA, a molecule cells already use to carry instructions for making proteins. In a vaccine, the message contains instructions for a harmless piece or feature of a target germ. Your cells read the message briefly and make that piece; the immune system then notices it and practises responding. The mRNA does not enter the cell nucleus, does not alter your genes, and is broken down after the instructions have been used. It cannot cause the infection it is designed to prevent.

The immune response can include soreness, tiredness, headache, chills, or fever for a short time. These effects reflect immune activity and are different from catching the infection itself.

Tell the vaccinator about a previous severe allergic reaction to a vaccine or one of its ingredients, current illness, pregnancy, immune conditions, and medicines. Follow the schedule offered for your age and health needs. After vaccination, remain in the observation area for the period advised by the clinic, drink fluids, and use simple comfort measures for a sore arm. Keep your vaccination record so future doses can be checked.

Seek urgent help for trouble breathing, swelling of the face or throat, widespread hives, fainting, or sudden severe weakness after vaccination. Contact a clinician promptly for chest pain, shortness of breath, a racing or irregular heartbeat, or symptoms that are severe, worsening, or not settling. A mild sore arm or brief fever can usually be monitored, but your clinician can help if you are unsure.

Ask which vaccine is recommended for you, which doses or timing apply, whether a past reaction changes your options, and what symptoms should prompt a call. You can also ask how vaccination fits with your existing medicines and other scheduled vaccines.