TOKYO — Japan said it’s investigating the deaths of two people who had Moderna Inc.’s COVID-19 vaccines as Tokyo’s seven-day average of new cases fell 16%, a sign its worst surge yet may be peaking.

While the relationship between the deaths and the shots is unclear, the Health Ministry will conduct the investigations together with external experts, and continue to assess the safety of the vaccine, according to a statement on Saturday.

Japan is investigating the death of two men who received jabs from batches of Moderna's COVID-19 vaccine suspended from use due to contamination, the Health Ministry said Saturday.

The men aged 30 and 38 died earlier this month after getting their second Moderna doses from one of three manufacturing lots suspended by the government on Thursday after several vials were found to be contaminated, the ministry said in a statement.

The ministry said the cause of death was still being investigated and "currently, causal relations with the vaccinations are unknown".

Both men contracted fever after receiving their vaccinations and neither had underlying health conditions or allergic history, the ministry said.

Japan halted the use of 1.63 million Moderna doses shipped to 863 vaccination centres nationwide, more than a week after the domestic distributor, Takeda Pharmaceutical Co , received reports of contaminants in some vials.

“At this time, we do not have any evidence that these deaths are caused by the Moderna COVID-19 vaccine,” Moderna and Takeda said in a statement on Saturday. “It is important to conduct a formal investigation to determine whether there is any connection.”

The government has also said no safety or efficacy issues had been identified and the suspension of the three Moderna batches was a precaution.

Fumie Sakamoto, the infection control manager at St. Luke’s International Hospital in Tokyo, cautioned against drawing a connection between the shots and the fatalities reported on Saturday.

“There may only be a temporal relationship between vaccination and death,” Sakamoto told Reuters. “There are so many things we still don’t know to make any conclusions on these two cases.”

The contaminants found in some vials in Japan are believed to be metallic particles, public broadcaster NHK reported, citing Health Ministry sources.

Japan has administered more than 124 million COVID-19 vaccine shots, with about 44 percent of the population fully inoculated.

As of Aug. 8, 991 people had died in Japan after receiving shots of Pfizer Inc’s vaccine and 11 after receiving Moderna’s, but no causality between the injections and the deaths has been established, according to the Health Ministry. Adverse reactions have been reported at a frequency of 0.01 percent for the Moderna shot. — Agencies