Dhaka, Bangladesh – One-year-old Saif Hasan died within minutes of being taken into intensive care at Dhaka’s Infectious Diseases Hospital (IDH) on August 27.

The child from the southern Bangladesh district of Shariatpur had developed a fever and rashes days after receiving his first measles-rubella vaccine. His family wondered whether the vaccine had made him ill.

But Saif, who had been receiving treatment for a pre-existing respiratory illness, was likely infected with measles before the vaccine had time to protect him, Shrebash Paul, a junior consultant at the hospital, said. “The infection then aggravated his underlying condition.”

Saif’s death points to the challenge Bangladesh faces in containing a measles epidemic that is now believed to have killed more than 1,000 people since March 15 this year. Last year, Bangladesh recorded 132 measles cases in total, with zero deaths.

The deaths come despite an emergency campaign that has administered nearly 20 million vaccine doses over this period.

By September 9, health authorities had recorded 1,009 deaths – 100 among laboratory-confirmed measles patients and 909 classified as suspected measles deaths. Yet the same official data shows 19.75 million children vaccinated since the emergency campaign began in April against the target of 18 million.

But public health experts say that apparently extraordinary figure helps expose one of the problems Bangladesh has faced in controlling the epidemic: On the one hand, the original estimate of the children needing vaccines was too low, while on the other, national coverage figures can obscure pockets where large numbers of susceptible children remain.

A target that underestimated the problem

Bangladesh’s vulnerability to measles did not emerge overnight.

The South Asian nation of about 178 million people had been moving towards eliminating the disease before years of declining immunisation coverage left a growing number of children susceptible.

Bangladesh’s 2023 Coverage Evaluation Survey found that first-dose measles-rubella coverage had declined from 88.6 percent in 2019 to 86 percent in 2023, while second-dose coverage fell from 89 percent to 80.7 percent.

Routine immunisation was disrupted during the COVID-19 pandemic, while UNICEF has also cited misinformation and vaccine hesitancy among factors contributing to children missing vaccinations.

Besides, before this year’s effort, Bangladesh had not conducted a nationwide supplementary measles-rubella campaign since the last one ran from December 2020 to January 2021. Coverage therefore remained below the approximately 95 percent level needed to interrupt measles transmission, allowing the number of susceptible children to grow over successive years.

The problem worsened amid political upheaval following the July 2024 uprising, when then-Prime Minister Sheikh Hasina was ousted, and disruptions to the country’s immunisation programme.

The change in government led to delays in vaccine procurement, said Mushtuq Hussain, a former principal scientific officer at Bangladesh’s Institute of Epidemiology, Disease Control and Research (IEDCR). That, in turn, led to vaccine shortages in 2024 and 2025.

Cases began rising markedly in January 2026 and surged through March, prompting Bangladesh to notify the World Health Organization (WHO) of a nationwide outbreak on April 4. By mid-April, cases had been reported in 58 of the country’s 64 districts.

When the current outbreak accelerated, authorities launched emergency vaccination in high-risk areas on April 5, followed by a nationwide campaign later that month. Authorities set a target of about 18 million children aged six months to under five years when the measles-rubella vaccination campaign was launched on April 20.

Yet, about two months later, on June 28, the government’s campaign to administer Vitamin A supplements targeted about 24 million children in the same age group – a difference of nearly six million. That discrepancy helps explain how Bangladesh can now report vaccinating almost 20 million children – exceeding its original target – while susceptible children continue to be found.

Hussain of the IEDCR questioned the population estimates used to set the vaccination target, saying they underestimated the number of eligible children.

Nationwide averages can also mask local gaps. “You have to maintain equity,” Hussain said, arguing that at least 95 percent coverage must be achieved across communities, including among hard-to-reach and mobile populations.

Numbers that can hide

Measles is among the world’s most contagious diseases, meaning even relatively small concentrations of unprotected people can sustain transmission.

Hussain said high national average coverage rates could conceal immunity gaps in individual communities, allowing the virus to continue circulating.

A second epidemiologist with extensive experience in Bangladesh’s immunisation programme, who requested anonymity because of the sensitivity of the issue, said authorities needed to analyse cases by age, vaccination history and location and use the findings to identify susceptible populations.

Without targeted vaccination of those populations, the epidemiologist said, transmission was likely to continue even if overall case numbers declined. Doctors treating patients are seeing evidence of those gaps.

Paul, the doctor at the IDH in Dhaka, told Al Jazeera that the majority of measles patients currently being admitted were unvaccinated. Some of the children now being treated had missed the vaccination campaign because they had been ill at the time.

Hospital admissions have nevertheless declined from their peak, Paul said, suggesting the vaccination programme has had a substantial effect. Still, children continue to arrive.

Babies dying before routine vaccination

The IDH’s mortality review provides another clue to why the outbreak has been so deadly.

As of August 23, the hospital had recorded 3,167 suspected measles cases, 537 laboratory-confirmed cases, and 57 confirmed or suspected measles deaths this year.

The deaths were overwhelmingly concentrated among very young children. Of the 57 who died, 49 – about 86 percent – were younger than 15 months, while 31 were younger than nine months, the age at which children in Bangladesh routinely receive their first measles-rubella dose.

Forty-seven of the 57 people who died – 83 percent – had received no measles vaccine, according to the hospital’s analysis. Pneumonia was recorded in 50 of the documented deaths – making it the leading responsible complication.

Paul said doctors were particularly concerned about infections among infants who had not yet reached the age for routine vaccination.

The IDH is studying children infected before nine months of age and their mothers to better understand the factors behind those infections. The hospital data should not be read as nationally representative, Paul said, adding that the IDH is a specialist referral hospital that receives serious patients from Dhaka and other parts of Bangladesh.

But the numbers provide a window into the children at greatest risk once measles spreads widely.

Health officials, meanwhile, say reported case numbers may not fully reflect the underlying trend.

Halimur Rashid, director of disease control at the Directorate General of Health Services (DGHS) — the government agency responsible for overseeing public health programmes — said authorities were preparing a further round of vaccinations, expected to begin within the next two weeks.

Can another vaccination drive stop it?

The next challenge will be reaching children missed by previous rounds. Experts say success will depend less on another large national coverage figure than on micro-planning – identifying susceptible children community by community and ensuring vaccinators reach them.

Hussain said authorities should consider extending vaccination to older children where surveillance identifies significant immunity gaps.

The epidemiologist who requested anonymity said vaccination may need to reach children up to 15 years old in affected areas.

But for too many families in Bangladesh, it is already too late.

Among those who fell through those gaps was Mostakim, a nine-month-old from east-central Kishoreganj district. He had not been vaccinated against measles.

On August 30, he died at the IDH.