The country's forensic agency said it found no causal link between the mass vaccination program and the rising number of deaths.

The government plans to push ahead despite calls for a suspension.

The National Forensic Service in South Korea announced to local media on Friday that it could find no causal link between the death of a 17-year-old boy and the flu vaccine he had been given.

Concerns over the vaccination program have grown following the recent deaths of at least 32 people who had previously been immunized. 

The deaths had sparked calls from doctors and politicians to end the vaccination program, but the Korean Disease Control and Prevention Agency (KDCA) announced on Friday that it would press ahead with its plan to immunize 30 million people against the flu in an attempt to avoid further potential complications with the novel coronavirus.

Death toll causing anxiety

An autopsy on the deceased teenager had revealed that the flu shot had not been the cause of death. Seven of the nine people whose deaths were investigated by the KDCA had underlying health problems.

Prime Minister Chung Sye-kyun called for a full investigation into the actual causes of death, saying in a meeting that "so far experts said there was low possibility that the shots and deaths were related but many citizens remain anxious."

He also sent his condolences to the families of those who had died.

Doctors call to suspend the program
The rising number of deaths led to the country's biggest group of doctors calling for the program to be suspended until the safety of the vaccine could be verified. At the same time a major vaccine organization said that the program should keep going since no link had been found between the vaccine and the deaths.

Some local governments had voluntarily advised residents not to take the shot or had considered unilaterally suspending the program.

KDCA chief Jeong Eun-kyeong said on Thursday that a possible option would be to suspend the use of vaccine doses with identification numbers matching those of batches manufactured at the same plant on the same day as batches which had been given to people who had then died.

The inoculation program has already vaccinated 8.3 million people against winter flu. Of those, around 350 people had reported adverse effects after the vaccination.