How the vaccine works
The COVID-19 vaccine from Moderna works by strengthening the body’s ability to defend itself against infection with coronavirus (COVID-19).
Prior to its authorisation, the Moderna vaccine was tested in major clinical trials with more than 28,000 voluntary trial subjects over the age of 18, and the vaccine demonstrated 94% efficacy against coronavirus two weeks after the second vaccine dose. In other words, there were 94% fewer COVID-19 cases among the trial subjects given the real vaccine than among those given a placebo.
Vaccinated people can still get ill if they are exposed to virus, but they will usually have milder symptoms than if they had not been vaccinated.
The vaccines’ benefits for the entire population are fewer hospital admissions, fewer severe disease cases and fewer deaths. The higher the infection rate, the greater the impact of vaccinating people, in overall terms.
To be fully vaccinated with the Moderna vaccine, two vaccine doses are given about four weeks apart.
Common side effects to expect after vaccination
All vaccines can cause side effects; the Moderna vaccine is no exception.
It is expected that more than half of those vaccinated will get mild side effects lasting for a few days such as tenderness where the injection was given, tiredness and headache.
More than one (1 to 2) in ten are likely to develop a fever.
Mild and moderate side effects, that pass within days, are common after vaccination and usually completely harmless. So, if you develop a mild fever or your muscles ache, this is a sign that your immune system is reacting. There is no need to contact your doctor about this. Further information about the mild and moderate side effects is provided in our information sheet and in the vaccine’s summary of product characteristics at www.ema.europa.eu.
If, on the other hand, you experience serious symptoms after vaccination, you should contact a doctor. Examples are allergic reactions like shortness of breath, swelling of the face or on the neck, and rash.
Please read our information sheet or the product information for details on all the known side effects (see links below).
Information sheet on the COVID-19 Vaccine Moderna from the Danish Medicines Agency