The Danish Health Authority is keeping its recommendation to refrain from vaccinating the population against coronavirus vaccine produced by AstraZeneca and Johnson&Johnson.

In a statement, the health authority explained that professional studies formed the basis of previous decisions to conduct a general vaccination program without the use of Janssen and Vaxzevria COVID-19 vaccines.

“Against this background, the authority still cannot recommend the use of the two vaccines at present,” the statement read.

Denmark repeatedly suspended these drugs from its national immunization campaign on April 14 and May 3 over reports of post-vaccination blood clots. Citizens, however, can be inoculated with these shots voluntarily and if approved by their physician.

According to its updated information, vaccines developed by Pfizer/BioNTech and Moderna were more effective against COVID-19.