Indonesia began revaccinating children on Monday after a revelation that hospitals and clinics had administered fake vaccines, prompting parents to attack doctors and other staff members.
The Health Ministry revealed last week that 14 hospitals and clinics in the capital and nearby cities had used fake vaccines, after police arrested more than a dozen people for allegedly making and distributing them across the country.
Protesters in Jakarta and neighbouring Bekasi rallied at several hospitals named by the ministry, and attacked staff members in at least two locations, the Indonesian Medical Association said.
"We will revaccinate the affected children in stages," Health Minister Nila Moeloek said.
She did not say how many children were injected with fake vaccines, saying that data were still being collected.
Police last month said they had arrested 15 people for alleged involvement in a criminal syndicate that has produced and distributed fake vaccines since 2003.
The revelation has shocked Indonesians and prompted questions about supervision of drugs and vaccines in the country.
The alleged ringleaders were a married couple who had posted photos of themselves on Facebook flaunting their luxury house and cars, police said.
The police said the syndicate had produced fake vaccines using intravenous solutions injected into old vials for 13 years and distributed them across the country.
Intravenous solutions are a sterile liquid used to supply fluids and sometimes nutrients or medication directly to a patient's bloodstream. They do not present a health risk, beyond failing to provide any of the protection of a real vaccination.