The staff took antigen tests before the event and were negative, which is making authorities question whether the dinner gathering was the cause of the outbreak, Spanish private news agency Europa Press reported.
The infected staff were all fully vaccinated and are showing no symptoms, Europa Press said, citing unidentified hospital sources.
The Andalucia province, where Malaga is located, has recently witnessed a rise in cases. Its 14-day infection rate stands at 136 cases per 100,000 inhabitants.
In Spain as a whole, that rate stood at 248 last Friday.
Authorities are also mindful of the new omicron variant, with 10 cases reported nationwide, though the scale of the threat from it isn't yet clear.
The regional government of the Balearic Islands in the Mediterranean, which includes Mallorca, announced Monday it had detected four new omicron cases. It found two other cases last week.
Follow AP’s pandemic coverage at https://apnews.com/hub/coronavirus-pandemic