Fever, coughing, muscle pain, and difficulty breathing. Sneezing, a runny nose, a sore throat, and general discomfort. Are these symptoms of Covid-19, influenza, or of an acute respiratory infection? The answer is all three. In their initial stages they are almost indistinguishable from each other. Knowing if someone has one, the other, or all three, is like finding a needle in a haystack. It is not easy.
The Mexican health care system will face the challenge of diagnosing and dealing with cases of influenza and acute respiratory infections alongside the Covid-19 pandemic, and these will begin to increase as they do every year after the rainy season.
This is not a small problem to solve, and one which could reach a peak in October. Data from the Epidemiology Department indicates that during 2019 there were 23 million cases of acute respiratory infection (which includes the common cold, bronchitis and bronchiolitis) and 6,833 cases of influenza.
“It will be very difficult for people to identify whether they have influenza or Covid, but that is the work of doctors and those of us who form part of the health care system: distinguishing between the illnesses or, where appropriate, between the people that have both,” said Malaquías López Cervantes, professor of Public Health from the Faculty of Medicine at the National Autonomous University of Mexico (UNAM). “People shouldn’t have to carry the burden of saying, ‘It’s up to me to know what I have.’”
For Rocío Tirado, an academic from the Department of Microbiology and Parasitology at the UNAM Faculty of Medicine, the key is to encourage differential diagnoses. That will be one of the defenses against the risks that this convergence of illnesses represents.
What are the risks?
In addition to the diagnosis, specialists have identified an even greater challenge: the saturation of hospital infrastructure in the event that outbreaks reach their peak at the same time or very close to each other. One problem would overlap with another.
“Yes, there is a possibility that outbreaks of these diseases will hit at the same time” said Mauricio Rodríguez Álvarez, a professor at the UNAM School of Medicine and spokesperson for the UNAM Covid-19 Commission. “Influenza causes significant hospital bed occupation which, when added to Covid-19, could overload hospital infrastructure.”
In addition, ventilators that currently assist in the treatment of patients who are critically ill with Covid-19 are also used in severe cases of influenza, so experts anticipate that there may be competition for resources.
“To give an example, there is a stage every year in intensive care at the National Institute of Respiratory Diseases (INER) at which it is (practically) full of patients with severe influenza, but right now it is full of patients with severe Covid,” explains the spokesperson for the UNAM Covid-19 Commission. “When the flu hits, one problem is going to add to another.”
Another big risk is coinfection, which means that the same person has two or more infections at the same time.
“This is the situation that I would be most concerned about: that there could be instances of coinfection. This is reported with many respiratory viruses,” warns Tirado. “It will be important to think about the viruses cocirculating, and that there will be patients who are coinfected not only from these two viruses, but from other respiratory viruses that are equally difficult to treat and against which there are no vaccines.”
Edward A. Belongia, director of the Center for Clinical Epidemiology and Population Health at the Marshfield Clinic Research Institute, and Michael T. Osterholm, director of the University of Minnesota’s Center for Infectious Disease Research and Policy, believe there are very few clues to how cases of coinfection were managed in China, the country where the SARS-CoV-2 pandemic originated.
“Few coinfections have been reported by China during the first phase of the pandemic. Influenza season in the southern hemisphere is just beginning and may provide some clues as to what to expect in the northern hemisphere later this year,” they wrote in an editorial for the journal Science.
Coinfections create a disaster in the immune system that can confound diagnosis.
“The risk is that doctors can’t distinguish them, and you get a treatment that is actually for the other virus, which can cause complications or delay medical treatment,” warns Rodríguez Álvarez. “A current example would be those with both coronavirus and dengue at the same time. It’s much more difficult, both for those making the diagnosis and those with the illnesses. The whole process is much more complicated.”
How can we prepare for viral convergence?
All acute viral infections are spread in the same way. Thus, the preventive measures followed for one may work for the others. Staying at home, social distancing, washing your hands frequently, and coughing into the crook of your arm, all of which protect against Covid, can be helpful against influenza and other acute respiratory infections.
Vaccination against influenza is also helpful. “Until we have a vaccine for Covid-19, it’s going to be difficult to control this process. But having an influenza vaccination scheme for the population means a large proportion of that population would be protected. Many others will have immunized themselves naturally and this, at the end of the day, more or less controls influenza outbreaks, which is something that wouldn’t happen with Covid,” explains this academic from the Department of Microbiology and Parasitology.
The experts acknowledge that vaccination during quarantine is a complicated task, but it must be done as soon as the vaccine is available and not only to vulnerable groups. They even suggest at-home vaccination campaigns and increasing (even doubling) the supply of influenza vaccines. For the 2019-2020 season, the Mexican Social Security Institute reported that just over 32 million doses were purchased.
“If we manage to reduce the number of influenza cases simply by vaccinating, we will be able to help identify and treat more Covid cases in a timely manner,” adds Rodríguez Álvarez.