RIO DE JANEIRO: Four months into a Covid-19 vaccination campaign marred by shortages and delays, hard-hit Brazil is still struggling to find enough doses, as political and diplomatic blunders prolong its pandemic nightmare.

Around 33 million people -- 15 percent of the population -- have received at least one vaccine dose in Brazil, a proportion still too small to have a substantial impact on the virus' spread.

Targeted by a Senate inquiry over its handling of the pandemic, President Jair Bolsonaro's government is facing criticism for failing to secure more vaccines, including its refusal of offers to purchase millions of doses and diplomatic tension with China that may be slowing the import of vaccine ingredients.

"We don't have enough doses right now to vaccinate as fast as we should," said Margareth Dalcolmo, a pulmonologist and researcher at leading public health institute Fiocruz.

"We ought to be vaccinating younger people already, especially given that younger demographic groups are currently driving transmission," she told AFP.

But first, Brazil still has to vaccinate 80 million people from high-priority groups, including the elderly, indigenous people and health workers.

Vaccine doses meanwhile continue to arrive in a trickle -- although the government maintains it will be able to vaccinate all adults by the end of the year.

Brazil has lost more lives to Covid-19 than any country except the United States -- more than 430,000 -- and has one of the highest death tolls per capita in the world.

Though the current wave has eased somewhat since April, the virus is still killing a staggeringly high number of people in the country -- nearly 2,000 a day.