Flu and Covid grow with out-of-season cold and relaxation of measures; know how to differentiate

The Covid pandemic, while still responsible for around a hundred deaths a day, seems to be getting closer and closer to its final days.

Living with the coronavirus, it seems, is close to an equilibrium situation, when the number of new cases approaches the level known for other respiratory viruses, such as influenza and respiratory syncytial virus (RSV). This does not mean, however, that we are already completely free of the virus.

The off-season cold wave in much of the Southeast region of the country has caused new cases of flu that have already led to the capacity of hospitals. In addition, much of the younger population, including children under the age of 5, has not yet been vaccinated against Covid.

According to experts heard by the report, the new wave of colds and flu is largely caused by influenza A H3N2 (influenza virus), which presented a different seasonality period this year, as a result of the Covid pandemic itself.

“We are probably in the best period of coexistence with the coronavirus, and for that reason, with the relaxation of measures, back to school and back from agglomerations, influenza is circulating a lot, combined with low coverage of the flu vaccine”, explains the pediatrician and director of Immunization at the Brazilian Society of Pediatrics, Renato Kfouri.

In this scenario, flu and Covid symptoms can be confused, especially in people who have already received the full vaccination schedule – today, considered as three primary doses of any of the immunizers with two doses or two doses of Janssen followed by booster.

See below what are the main symptoms of flu and Covid, how to protect yourself and what measures to take if you have the flu or cold from one of the viruses.

How to differentiate flu and covid symptoms?

According to experts, the differentiation of flu and Covid symptoms is not clear, especially in vaccinated people. In general, the most common symptoms of infection with the omicron variant of the coronavirus are sore throat, headache, runny nose and fatigue (tiredness). Other symptoms that may appear are sneezing, coughing, fever, body aches and loss of smell or taste, although the latter is no longer as common as with other variants of the coronavirus.

For Kfouri, flu and Covid symptoms in people vaccinated with at least three doses are almost indistinguishable. “It may even be that influenza gives more high fever, arrives with a stronger malaise on the first day, while Covid takes 1 to 3 days to manifest symptoms, it can cause more sore throat, loss of smell. But the only way to differentiate is with a test”, he explains.

According to the infectious disease specialist and medical director of Grupo Fleury, Celso Granato, the high circulation of the influenza virus at the moment, especially in São Paulo, is also reflected in laboratory tests. “Two, three weeks ago, when it was still the winter period, two or three cases of flu were reported a week. Now, in the past week, there were 1,480 cases, and the week before, 1,577, that is, an explosion” , explains.

For him, the greater circulation of the flu virus may indicate that the probability of an infection today being by influenza is greater than by the coronavirus, whose positivity of the tests is around 1.5% to 2%. “But we still have cases, although much less than at the beginning of the year.”

For Raquel Stucchi, a professor at Unicamp and a member of the Brazilian Society of Infectious Diseases of São Paulo (SBI-SP), in an ideal scenario, there would be a test for influenza also in the public network, but the offer is very scarce. “Taking the test when you have flu symptoms to rule out whether or not it’s Covid is the first step,” she says.

I’m vaccinated with three or four doses for Covid. Can I get infected by the omicron?

Granato, from Fleury, says that in the case of people vaccinated with three or more doses, the infection by the omicron can still occur, especially since the vaccines used so far have greater protection for moderate to severe cases, but less effectiveness in preventing the entry of the virus. virus.

“Some studies show that the added protection of a booster from the updated Omicron vaccines is slightly greater for mild infections. It will be important in the future that inhaled or nasal spray vaccines are given as they act to block the virus in your gateway, which are the airways”, he says.

Kfouri explains that vaccines that have been used in much of the world and in Brazil still maintain high protection against severe and moderate cases of Covid, even with the ômicron, around 80% to 90%, depending on the immunizer. “But what studies have shown us is that after six months the protection against infection is much lower, around 15% to 18%, so people can still get infected with the virus,” he says.

Why is the flu virus circulating more now?

According to Kfouri, the Covid pandemic has led to a change in the so-called seasonality of all respiratory viruses, including influenza. This change may have been partly because the protective measures against Covid stopped the circulation of these other viruses in the first two years of the pandemic and also because the so-called collective immunities ended up being affected – normally, living with other children leads to new infections by respiratory viruses as it generates the so-called “herd immunity”.

Because of this, the viruses began to circulate with greater intensity in periods that were not known in other years, such as the flu epidemic that occurred in December 2021, across the country, and the new outbreaks in late winter and early spring. spring, also a period of return to face-to-face classes, in São Paulo.

Should I wear a mask to avoid infection?

Risk assessment today, with the withdrawal of public health protection measures, becomes individual, experts say.

Stucchi says that the withdrawal of measures was justified by the more favorable epidemiological moment, but that the use of masks in closed spaces is still recommended in certain situations. “Some people who have underlying diseases [como doenças cardíacas, pulmonares, diabetes, hipertensão, etc.] may have a picture worsened by a viral infection even vaccinated. So, in these people, the use of masks can be considered from the risk of the infection causing what we call decompensation of the underlying disease”, he says.

The use of masks remains a protective barrier for any respiratory virus, says Granato. “For a person at greater risk, a flu infection is also not a positive thing, it can evolve into a serious condition, so these people can continue to wear a mask if they go to a crowded supermarket, use public transport or otherwise be in a place of high risk, regardless of the virus in circulation at the moment”, he says.

I got the flu shot at the beginning of the year, am I protected from the new strain?

According to Kfouri, the protection of the flu vaccine is around 40% and lasts about six months. In this way, people who received the immunizer at the beginning of the year, after the epidemic at the end of 2021, should have reduced protection. “It is still not possible to know if the strain that is in circulation now or the one that will be dominant in the season itself is the same as the vaccine that was applied. Therefore, the best thing now is to wait and, in people at greater risk, maintain some precautions to avoid infection”, he says.

How can I protect others if I have the flu or a cold?

For Stucchi, the step by step if you show signs of respiratory syndrome is first, use a mask to avoid transmission to other people; next, diagnosis to confirm or rule out infection by coronavirus or other viruses are important steps.

The infectious disease specialist also reinforces that the age groups of the two extremes, that is, both children and the elderly, are at greater risk of developing severe flu or Covid, and that vaccination coverage in them is less than ideal.