Are we sicker after the pandemic? Experts analyze outbreaks of infections

Earlier this year, the World Health Organization (WHO) warned of an increase in measles cases worldwide. The increase in whooping cough cases in Brazil this year is another issue that concerns the Ministry of Health. Also in 2024, deaths associated with dengue fever reached historic numbers in the country, with a significant increase in confirmed cases compared to last year.

Despite this, the increase in infections is not a phenomenon exclusive to Brazil. analysis A survey by healthcare consultancy Airfinity and Bloomberg News showed that in 44 countries or territories, at least one infectious disease caused an outbreak ten times larger than pre-pandemic numbers. The survey gathered data from more than 60 health organizations and agencies from different parts of the world.

The recorded outbreaks were of 13 communicable diseases, including flu, measles, polio, dengue and tuberculosis .

But, after all, are we really getting sicker after the pandemic?

According to Alexandre Naime, an infectious disease specialist and scientific coordinator of the Brazilian Society of Infectious Diseases (SBI), there is no scientific evidence that we are getting sicker after the Covid-19 pandemic. “However, there are repercussions resulting from actions that were taking place during the pandemic,” he explains.

This is the case of the drop in vaccination coverage for diseases that have already been eradicated. This phenomenon, which has been occurring since 2018, was significant during the pandemic. BCG vaccination coverage – which prevents severe forms of tuberculosis – applied to children aged zero to under five years old, had a rate above 95% in 2018. In 2019, it was 86.67%; in 2021, demand for the vaccine fell to 65.63%. Regarding the polio vaccine, coverage was 89.59% in 2018; in 2021, it was 66.62%.

“During the pandemic, due to the spread of fake news, there was an adherence to the anti-vaccine agenda, which affected not only the vaccine against Covid-19, but all vaccination coverage”, says Naime, CNN .

Furthermore, distrust in vaccination may be related to the lack of perception of disease risk, according to Rosana Richtmann, an infectious disease specialist and vaccine consultant at Delboni, a brand belonging to Dasa, a health services network.

“Whenever a person is unfamiliar with a disease because they have never seen cases, it is precisely because the disease has been eliminated, or at least partially eliminated, thanks to vaccination. Consequently, the person ends up not being afraid of the disease, so they do not perceive the risk and do not get vaccinated,” he explains.

“This is something really worrying and there is a lot of fake news being spread that prevents ordinary citizens from knowing the science and the truth, which creates doubts about the effectiveness and safety of the vaccine,” he adds.

Social isolation during the pandemic can also be a factor

The social isolation imposed by the Covid-19 pandemic to try to contain the transmission of the virus may also have been a factor related to the increase in cases of other respiratory infections or those that are transmitted through contact. “This can be observed, mainly, in cases of Respiratory Syncytial Virus (RSV) infection, which, during the pandemic, almost disappeared, and are now increasing again”, says Naime.

Second data from the Centers for Disease Control and Prevention (CDC) in the United States, flu cases in the North American country increased by about 40% in the two post-pandemic flu seasons.

In Brazil, there has also been an increase in cases of Severe Acute Respiratory Syndrome (SARS), a flu-like illness that progresses with respiratory impairment and can lead to hospitalization. In 2024, up to July 6, 44,228 hospitalized cases were reported, 44% due to RSV, 20% due to influenza and 14% due to rhinovirus, according to data from the Influenza Epidemiological Surveillance (SIVEP-Gripe), of the Ministry of Health.

This figure is already higher than the total number of cases reported in 2019, for the entire year: 40,294. Of the total number of positive cases for influenza and other viruses (32,963), 17.6% were classified as influenza and 23.5% as other respiratory viruses, according to SIVEP-Gripe.

“During the pandemic years, the Covid-19 and flu viruses were competing for the same host. Although there is the possibility of co-infection, one virus usually prevails over the other,” explains Naime. “During the pandemic, the Covid-19 virus predominated and, consequently, many people had no contact with the current flu virus and are now completely susceptible. This is without taking into account the low vaccination rate, which includes the flu vaccine,” he adds.

Climate change and increase in dengue cases

This year, up to June, Brazil registered 6 million cases of dengue, a number four times higher than the whole of 2023, according to data from the Ministry of Health’s dashboard. The number of deaths also broke a record this year, reaching 4,000 deaths up to June of this year, while in 2023, the total was 1,179.

Although there is no specific relationship with the Covid-19 pandemic, there has been an increase in cases and deaths from the disease since the beginning of the post-pandemic period. In 2021, the number of deaths from dengue was 325. In 2022, it was 1,053. According to Naime, this is mainly related to climatic factors, such as the increase in average temperature across the country.

“Due to this increase in temperature, places where there was previously no significant circulation of the dengue virus, such as southern states, are now experiencing epidemics as well. In other words, dengue is crossing borders,” he says.

These borders also include other countries where dengue was not previously as common. In June, the U.S. CDC issued a warning about an increased risk of dengue infections in the United States. The number of dengue cases reported in the Americas exceeded 9.7 million during the period between Jan. 1 and June 24, twice as many as in all of 2023, the CDC said.

The fact that dengue fever was not common in these places also ends up being a factor in the increase in cases. “We know that contact with the virus leads to immunity against the specific subtype of the virus [a dengue possui quatro subtipos, no total]”, explains Naime. “So, those who have never had contact with any subtype end up being more susceptible to the disease”, he adds.

What to do to strengthen immunity?

For Richtmann, the best way to improving immunity is through vaccination . “Vaccines provide specific immunity to specific diseases,” he says. “Another way to strengthen immunity is, without a doubt, by adopting healthy habits, such as regular exercise, healthy eating, adequate hydration, regular check-ups and taking care of our health, especially with preventive measures against diseases,” he adds.

Naime also proposes four fundamental steps for immune health:

1. Keep your vaccination record up to date;
2. For those who have the financial means, seek out vaccines offered by the private network to complete vaccination coverage against various diseases;
3. People in risk groups should avoid contact with infected people or continue to wear masks in crowded places. The same applies to healthy people who come into contact with people at risk of serious complications from infectious diseases;
4. Maintain habits that help prevent respiratory diseases, such as: washing your nose daily, especially in dry seasons (such as winter and autumn); avoiding prolonged exposure to cold; keeping environments ventilated; keeping your hands clean with soap and water or alcohol gel.

Understand how the immune system works beyond defending the body