The arrival of autumn on the 20th opens the season with the highest incidence of respiratory viruses in Brazil and coincides, this year, with the end of social isolation and the facilitate the use of masks . After the population’s low exposure to viruses in 2020 and 2021, precisely because of containment and protective measures, the change of season leaves the health sector on alert.
Influenza virus and respiratory syncytial virus (RSV), which has no vaccine, pose a risk to children, the elderly and immunocompromised people, experts say. Other than that, what worries me the most is low measles vaccination coverage .
The infectiologist Rosana Richtmann, of the Emílio Ribas hospital, in São Paulo, affirms that the vaccination campaign for influenza , scheduled for April, also includes the measles vaccine for children up to 5 years old. For her, in this age group the disease is more dangerous than Covid-19 itself:
“The reality is that we have not had a vaccination campaign in Brazil for the past two years, and there is an urgent need to vaccinate against measles, which can cause diseases such as encephalitis and meningitis and lead to death in children,” he said.
It was low vaccination rates that led to the resurgence of measles in the country in 2018 and the outbreak in 2019, with more than 20,000 cases.
A survey carried out at the request of the WORLD by public policy researcher Marina Bozzetto, from the University of São Paulo (USP), with data from the National Immunization Program Information System (PNI), shows that in 2021 the first dose of the MMR vaccine (measles , mumps and rubella) had 71.5% coverage, below the 95% target required for herd immunity. The second dose and the single dose of the tetraviral, which also includes varicella (chickenpox), reached only 56%.
In 2020, first-dose coverage was 79%, according to data from the Institute for Health Policy Studies.
Infectious disease specialist Julio Croda warns that the drop in vaccination coverage against various diseases, combined with the high transmission of respiratory viruses and the reduction of protective measures, can be an explosive combination.
“With the seasonal increase in respiratory viruses, as well as the return to school and activities without mask-wearing, the tendency is for these diseases to circulate again with the same intensity or greater intensity than in the past, either either because of low coverage, or because the virus hasn’t circulated for a long time and the population somehow loses its protection. There can be outbreaks,” says Croda.
Adults will also be more exposed. Influenza and RSV, one of the main causes of acute respiratory tract infection, can cause bronchial inflammation and pneumonia. In children, RSV can leave respiratory sequelae, such as asthma.
It is estimated that 90% of children under the age of 2, born during the pandemic, will now have their first contact with RSV.
The flu will have a vaccine this year with two new strains of virus, H3N2 (Influenza A), responsible for epidemics between the end of 2021 and January, and Victoria (Influenza B). So far, the Butantan Institute has delivered two million of the 80 million doses foreseen in the agreement with the federal government. No date has yet been set for the start of the campaign, which usually starts in April for groups at risk (elderly people, pregnant women and children).
For Alberto Chebabo, infectious disease specialist at DASA and president of the Brazilian Society of Infectious Diseases (SBI), there is another complicating factor. Although it is not known whether Ômicron will continue to circulate, part of the population will arrive in winter with fewer antibodies against Covid:
“There is a fall in antibodies from the fourth to the sixth month after the last dose of the vaccine. We may arrive in the months of May to July with an increase in the number of cases of susceptible people.”
Ekaterini Goudouris, director of the Brazilian Association of Allergy and Immunology, says people with allergies are also more vulnerable to viral infections because the mucous membranes of the airways maintain a minimum level of inflammation that exposes receptors to the virus.
“If everyone comes out of the cocoon with low vaccination coverage, the incidence of any type of virus can increase,” she says, who defends the maintenance of masks in closed environments and non-agglomeration.
Common viruses at this time of year include, for example, rhinoviruses and adenoviruses. Typically, they all initially produce similar respiratory ailments, which helps fill up hospitals. The symptoms are also similar to those of Ômicron.
With the popularization of tests, it is possible to subject the patient to a viral panel to identify the cause of the infection. Maria Amparo Martínez, pediatrics coordinator at Hospital 9 de Julho, in São Paulo, estimates that the number of cases of respiratory problems is expected to increase this year. In addition to seasonality, she recalls that there were more frequent epidemics, such as bronchiolitis, which increased the hospitalization of children between October and December 2021.
“Also, we increasingly realize that children are infected with more than one virus at the same time,” she says.
In early childhood, he explains, 80% of infectious diseases are viral. For specialists, vaccinating against the flu and keeping the calendar of other vaccinators up to date is essential. Although viruses are common, they can lead to secondary infections, such as pneumonia. Studies also show that, in adults, after contamination by the flu, heart attacks and cardiac arrhythmias increase.
“It has been proven that the flu virus is linked to cardiovascular complications. In the week following a flu, the risk increases”, explains Rosana Richtmann, from Emilio Ribas.
According to the infectiologist, attention is needed in the post-pandemic years:
“You have to be very vigilant. We need to have more flu cases, and that reinforces the importance of vaccination.”