Swiss pharmaceutical giant Novartis insisted early Thursday that its flu vaccines were safe despite a sales ban by Italy, Switzerland and Austria.
"Novartis confirms its confidence in the safety and efficacy of its seasonal influenza vaccines Agrippal and Fluad," the company said in a statement released overnight.
On Wednesday, Italian, Swiss and Austrian authorities stopped sales of the vaccines pending tests into possible side effects.
The alarm was first raised in Italy after white particles were seen in syringes carrying the vaccines, but Novartis stressed that "these particles can occur in the vaccine manufacturing process," adding it was "confident that there is no impact on the safety or efficacy of the vaccine."
The company said it had voluntarily provided Italian health authorities with its assessments "supporting the quality, efficacy and safety" of the vaccines, and that it would continue working with them in a bid to understand their decision to put a freeze on the vaccines.
Shortly after the Italian decision, the Swiss national drug agency Swissmedic also ordered an "immediate halt" of the vaccines due to "possible impurities", and were followed by Austrian health authorities.
The Swiss decision affects some 160,000 vaccine doses, Swissmedic said.
Novartis meanwhile stressed that it was "fully committed to providing high quality vaccines to patients and will continue to work with the authorities to make vaccines available."