BANGKOK (REUTERS) - Just two weeks before her long-awaited vaccine appointment in Bangkok, Ms Anyamanee Puttaraksa's 62-year-old mother became feverish. Three days later, her mother tested positive for Covid-19. Four hours afterwards, she died.

Alongside Ms Anyamanee's grief is anger at a vaccine roll-out that has left the elderly among Thailand's least-vaccinated groups - a contrast to much of the rest of the world, where vulnerable older people have been a priority.

"If she had been vaccinated, her symptoms wouldn't have been so severe," Ms Anyamanee said.

Government data analysed for the first time by Reuters shows that Thailand has fully vaccinated 6.7 per cent of an estimated 10.9 million people aged 60 and older, compared with 15 per cent of adults aged 18 to 59 and 10.2 per cent of the total population - including children, who are not being vaccinated.

Thailand was the only one of 30 countries for which Reuters reviewed data that had a lower percentage of seniors vaccinated than those in younger age groups.

Neighbouring Malaysia had fully vaccinated at least 64 per cent of its senior citizens by Aug 2, according to government data, compared with 42 per cent of its total population.

In Indonesia, only 17 per cent of the elderly have been fully vaccinated, but that is still higher than the 13 per cent for the total population.

Dr Chawetsan Namwat, a senior official at the Public Health Ministry's Department of Disease Control, said plans to prioritise the elderly shifted after a major outbreak in Bangkok and added that the relatively low rate of vaccinations in that age group could have led to more deaths among senior citizens.

Since April, people aged 60 and over have accounted for at least 62 per cent of deaths in Thailand and about 8.7 per cent of cases. The proportion of elderly deaths has risen, pointing to the possible impact of slow vaccinations.

In Indonesia, the elderly account for nearly 12 per cent of cases, but only 47 per cent of deaths.

Critics of Thailand's vaccination policy blame it in part for a spike to more than 10,000 deaths in a country where fewer than 100 people died of Covid-19 last year.

"The higher death toll now is a direct result of the failure to prioritise the elderly earlier," said Mr Chris Potranandana, co-founder of Zendai, a volunteer group helping the old and the poor access Covid-19 tests and treatment.

Dr Chawetsan said that the higher number of deaths in the current outbreak corresponded with higher case numbers and that death rates were only slightly higher in this outbreak.

Since April, Thailand's case fatality rate - the ratio between confirmed deaths and confirmed cases - has nearly tripled to 0.96 per cent, from the first two outbreaks' average of 0.33 per cent, data analysed by Reuters showed. The rate for the elderly is 7.2 per cent, up from 4 per cent earlier.

Although the government initially announced that the elderly would be a priority group for vaccinations, planning shifted from an age-based priority system to a geographically based one after an outbreak in Bangkok in April.

But younger and working-age groups in the capital ended up being able to access vaccination centres more easily than senior citizens, resulting in lower inoculation rates for the elderly, Dr Chawetsan said.

"We were going to prioritise the elderly but we didn't foresee the massive wave of infections from the Delta variant," Dr Chawetsan said. "When that happened, we had to pool our supply for the risk area with high infection rates and vaccinate all age groups there to curb infections."

Bangkok was allocated a third of Thailand's vaccine supply when the country's mass roll-out began in June, despite having only a tenth of the population, official data analysed by Reuters showed.

Another chunk of vaccines went to the tourist island of Phuket, where a government plan to vaccinate all adults has allowed it to resume limited international tourism.

A chaotic start to the vaccine roll-out could also have made it harder for the elderly, Mr Potranandana said. Vaccination bookings were invited on a plethora of mobile apps and websites and sometimes cancelled at short notice or set far in the future because of vaccine shortages.

"Access wasn't oriented towards the elderly, who are the least technologically savvy group," he said.

Dr Chawetsan said early registration numbers were also low because of vaccine hesitancy among the elderly.

The government says it now aims to step up vaccinations for the elderly. Dr Chawetsan said that 70 per cent or more of senior citizens should have at least gotten their first dose by the end of September.

A concerted vaccination push in Bangkok now means 97 per cent of senior citizens there have had at least one dose - higher than the 90 per cent for the city's total population - with 7 per cent of the elderly fully vaccinated.

Many families complain it came too late.

"They should have vaccinated the elderly right after health and front-line workers," said 18-year-old Thippawan Rodinthra, whose 78-year-old grandfather died of Covid-19 last month.

"Between grief and anger, I'm more angry at the government."