Measles returns in Bangladesh, the United States and São Paulo - critical summary review

The disease and the 95% threshold

Measles is a viral disease that travels through the air. It passes from person to person when someone coughs, sneezes, talks or simply breathes, and it spreads most easily indoors and in crowded places. Symptoms usually appear 7 to 14 days after exposure: high fever, cough, runny nose, conjunctivitis and red blotches on the skin. Once caught, it has no specific treatment. Severe cases can cause brain swelling and breathing problems. Two doses of vaccine prevent it.

It is also among the most contagious diseases in the world, which means even relatively small concentrations of unprotected people are enough to keep it circulating. That is why public health works with a threshold: roughly 95% vaccination coverage is needed to interrupt transmission. Below that, the number of susceptible people grows year after year, even when nothing visible is happening. And a national average can look comfortable while hiding pockets where almost nobody is protected.

That threshold is the backdrop for three pieces of news that landed in the same week, in three places with almost nothing else in common.

Bangladesh: the world's largest outbreak, and a target set too low

Bangladesh, a country of about 178 million people, is living through what the US Centers for Disease Control and Prevention has described as the largest measles outbreak in the world. Officials at the Directorate General of Health Services (DGHS), the government agency that oversees public health programmes, reported 187,484 infections since the outbreak began in March. By September 9, authorities had recorded 1,009 deaths, 100 among laboratory-confirmed patients and 909 classified as suspected. In all of last year, the country recorded 132 cases and no deaths.

"To my knowledge, Bangladesh has never witnessed so many children dying from measles," Mahmudur Rahman, former director of the Institute of Epidemiology, Disease Control and Research in Dhaka, told the Reuters news agency.

The gap opened before the virus surged. Bangladesh's 2023 Coverage Evaluation Survey found first-dose measles-rubella coverage had slipped from 88.6% in 2019 to 86%, while second-dose coverage fell from 89% to 80.7%. Routine immunisation was disrupted during the COVID-19 pandemic, and UNICEF has cited misinformation and vaccine hesitancy among the reasons children missed doses. The country had also not run a nationwide supplementary campaign since the one held between December 2020 and January 2021. Coverage stayed under the 95% mark.

Then came the political rupture. After the July 2024 uprising that ousted then-Prime Minister Sheikh Hasina, the change of government delayed vaccine procurement, according to Mushtuq Hussain, a former principal scientific officer at the institute, leading to shortages in 2024 and 2025. Health Minister Sardar Husain told parliament that changes to procurement policy in that period created a vaccine shortage.

Cases rose sharply from January 2026 and surged through March. Bangladesh notified the World Health Organization of a nationwide outbreak on April 4, and by mid-April cases had appeared in 58 of the country's 64 districts. Emergency vaccination began on April 5 in high-risk areas, followed by a national campaign from April 20 aimed at about 18 million children aged six months to under five.

Nearly 20 million children were vaccinated, more than the target, and susceptible children kept turning up. Part of the explanation is arithmetic: in June, a Vitamin A campaign covering the same age group targeted about 24 million children, nearly six million more than the measles drive had planned for. Hussain questioned the population estimates used to set the target. DGHS spokesman Zahid Raihan told the AFP news agency that "we couldn't achieve herd immunity", saying teams were still searching for missed children; official figures show roughly four million were never reached.

The deaths cluster among the youngest. At Dhaka's Infectious Diseases Hospital, of 57 confirmed or suspected measles deaths recorded this year up to August 23, 49 were children under 15 months and 31 were under nine months, the age at which children in Bangladesh routinely get their first dose. Forty-seven of the 57 had received no measles vaccine. Shrebash Paul, a junior consultant at the hospital, said most patients being admitted were unvaccinated and that admissions had fallen from their peak, while cautioning that the hospital is a specialist referral centre and its data is not nationally representative.

The United States eliminated measles in 2000 and is counting deaths again

Measles was declared eliminated in the United States in 2000. This year the CDC has counted 3,294 cases across more than 45 states, against 2,289 cases and three deaths in 2025.

All three deaths recorded in 2026 have been in Pennsylvania. Two were reported by authorities to have happened in August, in Lancaster County, a largely rural, agriculture-dependent area home to a large Amish population, a conservative Christian group with lower vaccination rates than other groups in the country. Both involved unvaccinated people, according to state health authorities. The third was a 40-year-old woman who died of complications associated with measles. "This is a heartbreaking loss for the family and an unfortunate reminder that measles can be a serious and potentially life-threatening disease," said Greg Furlong, medical examiner for Jefferson County, in a statement posted online. The Washington Post, citing Furlong, reported that she was unvaccinated.

Pennsylvania has recorded 676 cases this year, with 124 people hospitalised and nearly a third of cases in children. Fewer than 1% of the state's cases were in people who were fully vaccinated. Some experts have linked the disease's return in the US to rising vaccine scepticism.

The deaths have also become a political fight. The Trump administration has disputed the state's characterisation of the August deaths as measles-related and removed them from its national tally of the outbreak. Health and Human Services Secretary Robert F Kennedy Jr, a well-known vaccine sceptic, accused Pennsylvania's Democrat-led government of "weaponization of infectious disease fears for political gain" in a post on X and raised the possibility that the announcement "may even have been altogether fabricated". Governor Josh Shapiro accused Kennedy of spreading conspiracy theories and noted that Kennedy had spoken at an event in Lancaster County years earlier, "downplaying the severity of measles and saying that the cure was 'chicken soup and vitamin A'".

São Paulo: four transmission chains and vaccines with no paperwork

São Paulo state has confirmed 30 measles cases in 2026. In all of 2025 there were two. The capital accounts for 27, with two in São Bernardo do Campo and one in Guarulhos. The two most recent, confirmed on Wednesday the 9th, were children under 2 and are linked to transmission chains already being tracked by epidemiological surveillance teams.

Four chains have been identified in the state this year. The first, between March and April, was traced to two imported cases and was closed after 12 weeks with no related records. Those identified in June, July and August remain under monitoring, with teams investigating cases, following people who had contact with patients and assessing the need for further vaccination.

In August, a broad campaign ran in the capital, Guarulhos and São Bernardo do Campo, and more than 2.5 million doses were applied across the state that month. After the two new confirmations, the city of São Paulo resumed vaccination of everyone aged 6 months to 59 years in three districts in the north zone: Vila Maria, Vila Medeiros and Vila Guilherme. The vaccine offered is the triple viral, against measles, mumps and rubella. According to the Municipal Health Secretariat, no proof of prior vaccination is required and no proof of address either: anyone who turns up at a unit in those areas and says they live or work there will be vaccinated.

The same hole, in very different places

The three situations do not share a new virus. They share a gap in coverage, and the explanations given by the authorities in each place overlap.

In Bangladesh the sequence was pandemic disruption, misinformation and hesitancy cited by UNICEF, years without a supplementary campaign and then procurement delays after a change of government. In the US, where the disease had been eliminated a quarter of a century ago, the deaths occurred among unvaccinated people, and the return has been tied by some experts to growing vaccine scepticism, while the federal health secretary publicly questioned whether the first two deaths happened at all.

Hussain's point about national numbers applies to all of it. "You have to maintain equity," he said, arguing that at least 95% coverage has to be reached across communities, including hard-to-reach and mobile populations. It is the same logic behind São Paulo's response, which is drawn on a map of three districts rather than a state average.

What to do with this information

Check the family's vaccination record, and know what the record should show. Brazil's Health Ministry recommends two doses: the first at 12 months with the triple viral vaccine, and the second at 15 months with the tetraviral, which also protects against chickenpox, with a minimum interval of 30 days between them. People aged 1 to 29 should have two doses of the triple viral. Adults aged 30 to 59 should have at least one. Health workers need two doses regardless of age.

If you live in São Paulo, Guarulhos or São Bernardo do Campo, routine measles vaccination continues at Basic Health Units for the target groups even after the August campaigns ended, and the state health secretariat's guidance is to go to the nearest unit to check your status. Babies aged 6 months to 11 months and 29 days in those three cities can still receive the "dose zero" of the triple viral, ahead of the official schedule, and it may also be indicated for infants in that age range who had contact with suspected or confirmed cases. The dose zero does not replace the scheduled ones: the child should still receive the first dose at 12 months and the second at 15. In the three north-zone districts, anyone from 6 months to 59 years who lives or works there can be vaccinated without documents.

In the capital, vaccines are available at all Basic Health Units and at AMAs/integrated units from Monday to Friday, 7am to 7pm, and on Saturdays at the AMAs/integrated units. The nearest unit can be found through the city's Busca Saúde platform, and the state government keeps an information page on vaccination at vacina100duvidas.sp.gov.br.

What to watch next: in São Paulo, whether the chains identified in June, July and August go 12 weeks without new related cases, as the first one did. In Bangladesh, Halimur Rashid, director of disease control at the DGHS, said authorities were preparing a further round of vaccinations expected to begin within two weeks. Experts quoted by Al Jazeera argue that its success will depend less on another large national coverage figure than on identifying susceptible children community by community, with one epidemiologist saying vaccination may need to reach children up to 15 years old in affected areas.