In recent weeks, Moderna has had to deal with reports of contaminants discovered in vials of its COVID-19 vaccine in Japan.
Now it’s Pfizer doing the same after white floating matter was found in five unused vials of its COVID-19 vaccine.
The vials, which belonged to the same supply lot, were discovered between Saturday and Tuesday in two cities near Tokyo and in Sakai in the western part of the country, Kyodo News reports.
Officials said that vaccination sites continued to use shots from the same lot after visual inspection of vials showed no further contamination.
At a press conference on Wednesday, Pfizer’s Japanese subsidiary said the material was likely vaccine ingredients that had not been fully dissolved and would not affect the safety or the performance of the vaccine. Pfizer revealed that through Sept. 5, floating matter had been reported in 95 vials.
"The Pfizer-BioNTech COVID-19 vaccine is manufactured under the strictest of controls to ensure consistent identity, quality, purity and potency to assure patient safety and efficacy," the company said in a statement. "Pfizer is aware of the report, and is conducting a full investigation."
Last month, Japan halted the distribution of more than 1.6 million doses of the Moderna vaccine after metallic particles and rubber stopper material were found in three vaccine lots. Moderna traced the contamination to a manufacturer in Spain, Rovi Laboratories, which supplies vaccines to Japan.
Three deaths have been reported in Japan among recent recipients of the Moderna vaccine, but no link was established. Health officials in Japan and the U.S. said it was highly unlikely that the contaminants that were found could have caused fatalities.
After the Moderna snafus in Japan, its distribution partner there, Takeda, revealed a deal with U.S. COVID-19 vaccine maker Novavax to provide 150 million doses of its yet-to-be-approved shot to the government.
Both Pfizer and Moderna have had highly successful rollouts of their mRNA COVID-19 vaccines, suffering few regulatory delays, safety concerns and production and supply problems.