How effective are the approved mRNA vaccines?

In the studies for approval, the mRNA vaccines from Pfizer/BionTech and Moderna demonstrated an effectiveness against infection with Covid-19 of over 90 percent.

However, against the Omicron variant of Covid-19, which currently dominates in Switzerland, the protective effect against infection appears to be reduced. In contrast, the mRNA vaccines still offer a high level of protection against a severe course of disease, including against Omicron.

Protection from vaccination declines over time. Especially in older persons. A booster vaccination helps to increase the effectiveness again. The booster vaccination protects against severe infection for at least 3-6 months.

Several booster vaccines adapted to Omicron are authorized in Switzerland. Since March 2023, this also includes a vaccine from Moderna against the Omicron sub-variant BA.4/5 (Spikevax® Original / Omicron BA.4-5).

In studies, this adapted vaccine achieved a stronger immune response against the Omicron sub-variant BA.4/5 than the original vaccines.

It is not yet been conclusively determined whether the adapted vaccines also provide better protection against infection and a severe course of disease caused by Omicron than the original vaccines, and how long the protection lasts.