Shares of Moderna (MRNA) - Get Moderna, Inc. Report dropped Wednesday after the regulators in Sweden and Denmark halted COVID-19 shots from the company for younger people following cases of myocarditis.
The Swedish health agency said that it would pause using the shot for people born in 1991 and after as data pointed to cardiovascular side effects that include inflammation of the heart. Denmark will stop giving the shot to those younger than 18.
"The connection is especially clear when it comes to Moderna's vaccine Spikevax, especially after the second dose," the health agency said, according to Reuters. The agency noted that the side effects were rare.
Moderna on Wednesday closed down 8.9% to $302.42 in the regular session..
"These are typically mild cases and individuals tend to recover within a short time following standard treatment and rest. The risk of myocarditis is substantially increased for those who contract COVID-19, and vaccination is the best way to protect against this," Moderna told Reuters in an email.
The two countries recommended Pfizer-BioNTech's (PFE) - Get Pfizer Inc. Report (BNTX) - Get BioNTech SE Sponsored ADR Report vaccine as an alternative though both vaccines use messenger RNA technology to work.
In September, the companies said their latest trial results showed the vaccine had "robust neutralizing antibody responses" for children aged 5 to 11.
But Sweden's public health agency said that new preliminary data suggested the connection between vaccination and heart inflammation is clearest with the Moderna shot, Bloomberg reported.
Meanwhile, the Norwegian Institute of Public Health cited new data from Ontario, Canada as well as Norway in recommending that men under 30 consider choosing the Pfizer shot.