Coronavirus could become a seasonal infection like flu and return every year, say scientists
The new coronavirus could be here to stay. According to some experts, COVID-19 could become a seasonal infection like the seasonal flu.
Experts say COVID-19 could become seasonal in the same way that other coronaviruses are. According to the US Centers for Disease Control and Prevention (CDC), common human coronaviruses usually cause mild to moderate upper respiratory tract illnesses such as the common cold. Most people get infected with one or more of these viruses at some point in their lives.
Symptoms of common human coronaviruses include runny nose, sore throat, headache, fever, cough and a general feeling of being unwell. Human coronaviruses can sometimes cause lower respiratory tract illnesses such as pneumonia or bronchitis, says the CDC.
The reported illnesses in the COVID-19 outbreak have ranged from mild symptoms to severe illness and death for confirmed coronavirus disease 2019 or COVID-19 cases. The CDC says that symptoms may appear 2-14 days after exposure and include fever, cough and shortness of breath.
"It's a question of crystal ball gazing but if you look at other members of the coronavirus family, that are respiratory viruses and we have known about them for the last 50 years or more, they are seasonal. They are just like the common cold. There is probably a few thousand people infected with them at the moment in England," Professor John Oxford, a virologist from the Queen Mary University of London, told The Telegraph.
He said, "Whether COVID-19 will fit into that pattern or not, we will just have to wait and see but my guess is it will. It had enough characteristics similar to the viruses we have known about for the last 50 years for it to eventually settle down and become seasonal."
Amesh Adalja, an infectious-disease expert at the Johns Hopkins Centre for Health Security, told Business Insider, "This is going to be with us for some time – it's endemic in human populations and not going to go away without a vaccine."
There has been a global shift in the COVID-19 outbreak. While the number of infections has gone down in China, the numbers have soared in South Korea, Italy and Iran. The worldwide death toll is 3,117 and the number of cases are 90,936 in at least 60 countries.
Too early to say how COVID-19 will behave in future
There has been some speculation that warm summer temperatures might stop the outbreak. While seasonal influenza (flu) viruses, for example, are detected year-round in the US, flu viruses are most common during fall and winter.
"The exact timing and duration of flu seasons can vary, but influenza activity often begins to increase in October. Most of the time flu activity peaks between December and February, although activity can last as late as May," says the CDC.
But scientists caution that it is too early to make any predictions regarding how COVID-19 will behave in the future and more studies are needed to draw any conclusion.
Coronaviruses are known to spread more quickly in the winter because they can survive for long in a colder climate. A warm, humid weather makes it harder for respiratory droplets to spread viruses.
However, scientists said one should not assume that COVID-19 would taper down in summer and spring, and come back in winter.
"It would be reckless to assume that things will quiet down in spring and summer. We don't understand the basis of seasonality, and of course, we know absolutely nothing about this particular virus," Dr Peter Hotez, dean of the National School of Tropical Medicine at the Baylor College of Medicine in Texas, told CNN.
Dr Nancy Messionnier of the CDC also warned against assuming the number of cases will slow as the weather warms. "I think it’s premature to assume that. We haven’t been through even a single year with this pathogen," she said during a media briefing earlier this month.
"Rate of virus spread, the effectiveness of infection control practices, weather and human immunity will likely all play a role in determining its future," Elizabeth McGraw, director of the Center for Infectious Disease Dynamics at Pennsylvania State University, told TIME.
Experts further warn that even if the coronavirus becomes seasonal, it might not go anywhere.
Dr William Schaffner, an infectious disease specialist at Vanderbilt University Medical Center, told CNN, "It's a respiratory virus, and we know respiratory viruses are very seasonal, but not exclusively. One would hope that the gradual spring will help this virus recede. We can't be sure of that."
Charles Chiu, a professor of laboratory medicine at the University of California, San Francisco, told TIME, "If we continue to see sustained transmission in multiple countries, it will be very difficult to eradicate the virus. There is a risk that it may end up becoming a seasonal virus without global concerted public health interventions to prevent spread."
Flu and COVID-19 are different
According to experts, while influenza and COVID-19 are both infectious respiratory illnesses and their symptoms look similar, the two illnesses are caused by different viruses.
The report of the WHO-China Joint Mission on the new coronavirus emphasizes that COVID-19 is not SARS and it is not influenza. "It is a new virus with its own characteristics. For example, COVID-19 transmission in children appears to be limited compared with influenza, while the clinical picture differs from SARS. Such differences, while based on limited data, may be playing a role in the apparent efficacy of rigorously applied non-pharmaceutical, public health measures to interrupt chains of human-to-human transmission in a range of settings in China," it says.
The report adds, "The COVID-19 virus is unique among human coronaviruses in its combination of high transmissibility, substantial fatal outcomes in some high-risk groups, and ability to cause huge societal and economic disruption. For planning purposes, it must be assumed that the global population is susceptible to this virus. As the animal origin of the COVID-19 virus is unknown at present, the risk of reintroduction into previously infected areas must be constantly considered."
During a media briefing on March 2, Dr Tedros Adhanom Ghebreyesus reiterated that this virus is not influenza. "If this was an influenza epidemic, we would have expected to see widespread community transmission across the globe by now, and efforts to slow it down or contain it would not be feasible," he said.