BBC News, Sao Paulo
The World Health Organisation is sending two million doses of vaccine to Paraguay to combat the country's first outbreak of yellow fever in 34 years.
Some of those queuing for vaccines are growing impatient
Local people have been queuing for vaccinations following the outbreak in which seven people died.
Extra vaccines have been sent from other countries in the region. But large amounts of stocks have already been used up.
Paraguay has declared a state of emergency to last 90 days.
The mood of those queuing outside medical centres has become increasingly impatient.
At one medical centre, police in riot gear were reported to have been used to protect the building, as an angry crowd gathered outside.
The government has dismissed as "irresponsible" allegations that health workers have been vaccinating politicians in their homes.
To help meet demand Paraguay has been importing doses of the vaccine from neighbouring Latin American countries and from France, which is a leading supplier.
Brazil, which is also dealing with an outbreak of yellow fever in which 16 people have died, was among the countries to provide assistance.
The authorities in Paraguay say the World Health Organisation supply of vaccines is expected to arrive at some point this weekend.
Yellow fever is contracted through a mosquito bite and the symptoms include fever, muscle pain, nausea and vomiting.
Most people recover after a few days, but a second more toxic phase can prove fatal. It is thought that worldwide around 30,000 people die each year from the disease.