Influenza can progress into serious respiratory trouble that lands people in hospital beds needing oxygen.
Only 43% of priority groups vaccinated against influenza in RS, with particularly low rates among children (32%) despite winter arrival on June 21. Unvaccinated populations risk severe respiratory complications including pneumonia and death; winter conditions and El Niño may increase transmission in closed spaces.
- Only 43% of priority groups vaccinated against influenza in Rio Grande do Sul by campaign end
- Just 32% of children vaccinated; 61% of elderly; 50% of pregnant women
- 1.35 million of 3.13 million target doses administered; 5.2 million total expected
- Winter officially begins June 21; El Niño expected to bring above-average rainfall
- Hospital admissions for viral respiratory diseases up significantly since March
Rio Grande do Sul faces low flu vaccination rates (43% of priority groups) as winter approaches, with health authorities expanding access to all populations. El Niño weather patterns add concerns about increased respiratory illness transmission.
Rio Grande do Sul is heading into winter with a vaccination problem. As June arrives and the season officially turns on the 21st, health authorities are confronting a stubborn reality: fewer than half the people who should be protected against influenza have actually received the shot. The numbers tell the story plainly. By the time the state's vaccination campaign ended on Saturday, only 43 percent of priority groups had been vaccinated. Among children, the figure dropped to 32 percent. The elderly fared better at 61 percent, and pregnant women at 50 percent. In absolute terms, that meant 1.35 million people had received doses when 3.13 million should have. The state had distributed roughly 1.35 million of the 3.87 million doses it received, with the federal health ministry expected to send more, bringing the total available to 5.2 million.
In Porto Alegre, the capital, the picture was similarly thin. Just over 202,000 people from priority groups had been vaccinated—roughly half the target. Starting this week, municipalities gained the freedom to set their own vaccination strategies. Porto Alegre chose to open access to the entire population, offering doses to anyone who wanted one until supplies ran out. It was a pivot born of necessity: the narrow approach had failed to move the needle.
At Porto Alegre's Hospital de Clínicas, the low vaccination rates are setting off alarms. Caroline Deutschendorf, an infectious disease physician and head of the hospital's infection control committee, speaks plainly about what happens when people skip the shot. Influenza can progress into serious respiratory trouble—pneumonia, for instance—that lands people in hospital beds needing oxygen, sometimes fatally. The vaccine does not prevent infection entirely, but it shrinks the chance of these grave complications. It softens the illness, shortens its duration, keeps people out of the hospital. That matters enormously when winter arrives and people retreat indoors.
Deutschendorf points to what has already happened. Since March, the hospital has seen a significant rise in admissions for viral respiratory diseases. Winter will make it worse. When temperatures drop and people cluster in closed spaces, viruses spread more easily. The vulnerable—children under five, pregnant women, elderly people, anyone with a weakened immune system—face the highest risk. Beyond vaccination, she advises people to avoid crowded indoor spaces when possible, and absolutely to stay away from anyone who is coughing or sniffling. The vaccine is the foundation, but it is not the whole answer.
The timing could hardly be worse. June marks the shift into the Southern Hemisphere's winter, and climate models are signaling that El Niño will intensify the season's effects. The phenomenon is expected to bring above-average rainfall to Rio Grande do Sul, a state still raw from the catastrophic floods of 2024. Gilvan Sampaio, a researcher at Brazil's National Institute for Space Research, urges caution about predictions. The current models suggest a moderate El Niño, possibly stronger, but the full picture will not be clear until June and July data come in. "It is still early to say," he notes, "but we know the phenomenon will be at least moderately intense."
Venisse Schossler, a climate scientist at the Federal University of Rio Grande do Sul, offers a steadier perspective. There is a 98 percent chance El Niño will establish itself between June and August. But she pushes back against what she calls "climate panic." In 2023 and 2024, El Niño did not prove as severe as forecasts suggested. In 2016, when it was considered very strong, the flooding was far less dramatic than what happened in 2024. Weather prediction models are most reliable about two weeks out; beyond that, too many variables shift—moisture from the Amazon, cold fronts from Antarctica, local geography. The state should prepare, she is saying, but not panic. Still, the convergence of low vaccination rates, winter's arrival, and the possibility of heavy rain creates a scenario that health officials cannot ignore. The state is now racing to get more people vaccinated before the season deepens.
Notable Quotes
Influenza can lead to serious respiratory complications like pneumonia requiring hospitalization and oxygen, potentially fatal. Vaccination reduces the chance of these complications.— Caroline Deutschendorf, infectious disease physician, Hospital de Clínicas de Porto Alegre
It is still early to say, but we know the phenomenon will be at least moderately intense.— Gilvan Sampaio, researcher, National Institute for Space Research
The Hearth Conversation Another angle on the story
Why did the vaccination campaign fall so short? Forty-three percent seems like a number that should have triggered an earlier response.
The campaign ran its course and ended on Saturday. By then, the gap was clear—especially among children, where only a third had been vaccinated. The state had the doses; people simply did not come. So municipalities pivoted. Porto Alegre opened it to everyone.
And that works? Just opening the doors?
It is a different strategy. Instead of targeting priority groups and hoping they show up, you make it available to anyone. Some people will come. Whether it is enough before winter hits—that is the real question.
The doctor mentioned pneumonia and death. Is that common with flu?
It is not the most common outcome, but it is real. Most people get sick and recover. But some develop pneumonia, need hospitalization, need oxygen. For vulnerable people—very young children, the elderly, pregnant women—the risk is higher. The vaccine does not stop infection, but it reduces the chance of those severe complications.
And El Niño makes this worse?
It could. More rain, colder weather, people indoors more. That is when respiratory viruses spread fastest. But the climate scientists are cautious about predictions. They have been wrong before.
So the state is caught between two uncertainties.
Exactly. Low vaccination rates heading into winter, with a weather pattern that might bring heavy rain and keep people inside. Neither is certain, but together they create a scenario worth taking seriously.