The father of one of 17 infants who died after receiving hepatitis B vaccine on Friday dismissed as "total rubbish" claims by Chinese officials that the deaths were unrelated to the inoculation.
Nine of the babies' deaths had nothing to do with the vaccines, the official news agency Xinhua quoted disease control and prevention official Yu Jingjin as saying on Friday.
Autopsies had yet to be carried out on the remaining eight infants, but a "preliminary analysis" also showed no link between the deaths and the vaccines, Yu said.
Shanxi-based Yang Wenlong, whose own child was among those who died, said the official account of the babies' deaths was groundless.
"They are talking absolute rubbish, and no one in China will believe it unless they are idiots," Yang said.
"I for one don't believe their results."
He said Yu's account had been roundly criticized by Chinese netizens, who are deeply suspicious of the government following a series of product safety and public health scandals in recent years.
"If you look at [chat site] QQ and online, you will see how many people are cursing him," Yang said. "I think they are afraid of affecting people's uptake of the vaccine."
"But I think that what they've done here will have the opposite effect to the one they intended."
The deaths were reported following inoculation with a hepatitis B vaccine, made by Shenzhen-based BioKangtai, between Dec. 13 and Dec. 31.
BioKangtai said in a statement last month that it has "rigorously" followed safety rules but that company is also testing the batches concerned.
On popular social media sites, many commentators agreed with Yang, however.
"Seventeen lives have been lost, and you still talk about your vaccine being viable?" wrote user @sz1961sy. "We call on relevant experts to carry out some research in the hospitals with a view to protecting young lives."
Parent activist Zhao Lianhai, whose child was made ill by melamine in the 2008 tainted milk formula scandal, said there had been well-documented cases of tainted vaccines before in China.
"This has been going on for years now," Zhao said. "We have met with the parents of children affected by tainted vaccines, but they have never won any sort of redress."
He called for an investigation into the source of the problem. "There should be an investigation in all areas [of vaccine production, storage and administration]," he said. "This cannot be tolerated."
"Is it with the vaccines themselves, or with the hospital?" he said.
"Some companies in China have common interests with certain government departments," Zhao said. "This is pretty much an open secret nowadays."
"If problems occur, they use their relationships [with government] or money to get around it."
China's pharmaceutical industry is highly lucrative but poorly regulated, resulting in a string of fatalities blamed on counterfeit or shoddy medications in recent years.
An investigative report in the China Economic Observer newspaper in 2010 said that improperly stored vaccines administered by Shanxi health officials for encephalitis, hepatitis B, and rabies between 2006 and 2008 had killed four children and sickened more than 70 others, with tainted vaccines being used as late as March 2009.
Top investigative reporter Wang Keqin, who exposed the vaccine scandal among others, was forced out of his job at the newspaper in February 2013.
Parents who complain about mishaps linked to health and safety issues say they are frequently themselves targeted for official harassment and punishment.
In 2011, authorities in Beijing sentenced parent activist Yang Yukui to five months' "re-education through labor" on charges of "provoking disputes and causing trouble" after he complained that his son had been in and out of the hospital since being given a bacille Calmette-Guerin (BCG) tuberculosis vaccination shortly after birth.
Reported by Yang Fan for RFA's Mandarin Service. Translated and written in English by Luisetta Mudie.