Concurrent Combatants: COVID-19 and the Flu

Ever since the beginning of the coronavirus pandemic, life as we had known it changed drastically. With the virus spreading rapidly and cases nationwide skyrocketing, scientists are left baffled and searching frantically for a vaccine. Unfortunately, time is of the essence. With the imminent flu season fast approaching, health experts are alarmed by the chilling prospect of battling both influenza and the coronavirus pandemic at once.

Though sometimes overlooked thanks to the annual flu vaccine, influenza is one of the deadliest illnesses worldwide, killing up to 650 thousand people annually. While some countries are managing the coronavirus pandemic effectively, others, such as the United States, are facing the terrors of a “second wave.” Due to the rapid influx of cases, already strained hospitals and clinics dread a pileup of new respiratory infections, including influenza and respiratory syncytial virus (RSV) (a virus that causes respiratory tract infections in young children), as explained by the American Association for the Advancement of Science. Health experts and researchers are apprehensive of what the flu season will bring when combined with the disaster of COVID-19 that still wreaks havoc upon the world. For a sneak peek into what the pandemic has in store for the Northern Hemisphere come wintertime, researchers turned to countries located in the Southern Hemisphere, including South Africa, New Zealand, and Australia.

The Southern Hemisphere braced for the winter flu season while fighting COVID-19 in March 2020. Epidemiologists at South Africa’s National Institute of Communicable Diseases observed the interactions between seasonal respiratory viruses and the coronavirus and were presented with a perplexing phenomenon: the flu was essentially absent from the population. Most regions were reporting higher than 10 percent test positivity for seasonal influenza, and the most heavily hit areas reported over 30 percent test positivity in July 2019, peak influenza season in the Southern Hemisphere. In comparison, no region has reported more than 10 percent test positivity, and a few regions in Southeast Asia, South America, and Africa have reported zero cases of the flu altogether as of July 2020. However, there are many possible explanations for this strange occurrence, including the overlooking of cases as clinics closed, travel restrictions, school closures, social distancing, and mask-wearing.

While overall positive, this situation gives scientists little to work with to determine how the coronavirus might influence the course of a flu outbreak in the Northern Hemisphere. Nevertheless, some researchers, like Ian Barr, deputy director of the World Health Organization, are stating their concerns regarding a dangerous process known as “coinfection.” In virology, coinfection refers to the simultaneous contraction of pathogenic cells from two or more different particles (in this case, COVID-19 and influenza).

Previous studies have confirmed that coinfection with multiple respiratory viruses is possible. An experiment conducted in Northern California during April 2020 analyzed COVID-19 cases in conjunction with other respiratory viruses, such as RSV and rhinoviruses (the common cold). Their data revealed that of 318 specimens positive for one or more non-coronavirus pathogens, 24 (7.5 percent) were also positive for the coronavirus. While this number is relatively low, it still signifies the possibility of coinfection with other pathogens. More importantly, a study recently published in the Journal of Medical Virology found that coinfection of last year’s strain of influenza and the coronavirus was very common during the initial outbreak of COVID-19 in Wuhan, China. According to the results of the study, patients coinfected with COVID-19 and influenza were more likely to develop fatigue, chest CT abnormalities, or decreased lymphocytes and eosinophils (the body’s main types of immune cells), both of which indicate more severe disease. Additionally, patients who were coinfected with influenza were found to have a higher rate of presenting poor prognosis (30.4 percent) in comparison with patients who contracted either COVID-19 (7.6 percent) or influenza (5.9 percent).

These studies indicate that the impending winter in the Northern Hemisphere will bring about coinfections of the flu and coronavirus. Should coinfection occur, patients’ symptoms and clinical distress might be exacerbated due to the presence of, not one, but two viruses in their bloodstream. In order to capture more accurate data and make the appropriate research and treatment choices, scientists believe that dual diagnostic tests (to test patients for COVID-19 and influenza at once) should be developed. As a matter of fact, the U.S. Food and Drug Administration has already “issued emergency use authorizations for flu-COVID-19 combination tests,” which could mean that more efficient testing is well on its way to becoming a reality.

Furthermore, the heightened necessity of the coming season has boosted the production of flu vaccines. Vaccine manufacturers, namely GlaxoSmithKline and AstraZeneca, increased their production of the 2020 flu vaccine by 20 million doses, according to the Centers for Disease Control and Prevention. This action is justified by the fact that preventing the flu will “keep hospital admission down as health systems grapple with the pandemic.” However, several detractors, such as Pasi Penttinen, head of the influenza and respiratory illness program at the European Center for Disease Prevention and Control, warn of the possibility of a minor flu season like the one that took place in the Southern Hemisphere just earlier this year. Penttinen believes that “pouring resources into an immunization campaign necessarily subtracts from COVID-19 response,” a risk that he and other critics are unwilling to take.

There is no doubt that our current predicament will play a crucial role in taking scientific research to the next level. Unraveling the complications of coinfection and determining the most effective method of vaccinating and testing during the upcoming season forces researchers to throw caution to the wind and pursue answers. Whether the flu rears its head over the next few months or not, the best we can do is be prepared for whatever comes next.