The spread, of the coronavirus is increasing exponentially. The researchers are worrying that the virus will spread all over the world. But nothing is lost yet.
The new coronavirus that started in Wuhan, China, “SARS-Cov-2”, is now likely to become a global pandemic. This is what many infectious disease experts think out loud. Professor Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases and a pioneer on AIDS, is convinced of this and says so in an interview with the New York Times.
According to the same scientists, at this stage, the Wuhan coronavirus spreads more like the flu, which is highly transmissible, than its slower coronavirus cousins, such as SARS and MERS. This is confirmed by a study in the Lancet, and another in the New England Journal of Medicine, which estimates that at this early stage of the epidemic the number of cases doubles every 7.4 days!
In the last three weeks, the number of laboratory-confirmed cases has increased from around 50 in China to more than 20,000 officially (equivalent to more than 100,000 according to conventional epidemiological models), with more than 400 reported deaths. However, these figures change every day.
For comparison, when SARS was contained after nine months of spread in 2003, only 8,098 cases were confirmed. The other deadly coronavirus, MERS, has been circulating on the Arabian Peninsula since 2012, but only about 2,500 cases have been detected.
With the exception of the mutation, which would reduce its transmission potential, Professor Fauci considers it increasingly unlikely that this epidemic can be contained for long. Borders, even when closed, will always be permeable, especially if the Chinese coronavirus spreads, as is likely, like the flu. At this stage, however, experts do not yet know how lethal it will be.
The mortality rate is not yet known
In fact, lethality is estimated on the basis of populations that have not yet been properly screened. It is currently estimated at 2% for this new coronavirus. This is less than for SARS (10%) and MERS (30%), but much more than for influenza (less than 0.1% in total, except for 1918 H1N1, which would have reached 2.5%). However, if 2019-nCorV is as contagious as influenza, the epidemic is likely to become a pandemic.
However, an accurate estimation of the lethality of the virus will only be possible when studies can be carried out based on an accurate virological diagnosis: routine blood tests in populations to see how many people have antibodies (and thus have come into contact with the virus), households screenings to find out how often the coronavirus infects members of a patient’s family, and genetic sequencing to determine whether certain strains are more dangerous than others.
Infectious before the first symptoms occur
Several reports from China and a study from Germany, published in the New England Journal of Medicine, indicate that some people infected with the new coronavirus can transmit it even before they show symptoms (“incubation”). In the few studies available, the incubation time is on average 5 days, but with large differences (up to 12 days).
This makes border control even more difficult: if thermal cameras can’t detect patients who are already infected but show no symptoms, and are therefore able to actively infect others, the actual number of asymptomatic patients missed may exceed 75%, again according to experts.
The calm before the storm
Life in China has changed dramatically in recent weeks. Entire cities and regions are under quarantine, people are being locked in their homes, streets are being abandoned, public events are being canceled and those who venture out to buy food are wearing masks and constantly washing their hands. All this may have slowed down the spread of the virus, but it cannot last forever.
Other important uncertainties in this epidemic are: who is most at risk, is it the coughing or the infected surfaces that are more likely to transmit the virus, how quickly can the virus mutate, and will it disappear when it warms up again? All these factors can reduce or increase the rate of infection.
Gaining time is crucial
Although experts believe that closing borders for highly contagious pathogens is never completely successful, still, quarantines and rigorous virus testing can delay the spread of the disease.
For the time being, experts believe that the virus is unlikely to spread on a large scale this winter in countries with efficient healthcare systems.
But the most at-risk areas for the coronavirus are parts of Asia, but more importantly, Africa. More than a million Chinese immigrants work there and many Africans work and study in China. If anyone in some of the sub-Saharan African countries has the virus right now, it’s not certain that the local health care system can detect it. So we have to rely on the sun’s heat!
Rely on seasonality
Sun and heat are indeed key elements for this problem. Many viruses, such as flu, measles, and noroviruses, spread very well in cold air and less well in warm air. The same may be true for this coronavirus since the SARS epidemic started in the winter, and MERS transmission also peaked then.
But even if the current epidemic stops in June, there may be a second autumn wave, as was the case with all major flu pandemics, including those that started in 1918 and 2009.
A small delay that allows scientists to find new treatments
Hopefully, before the next wave, some treatments may already be developed. In any case, viral cultures are already available to test for all potentially effective medications.
Although modern techniques make it possible to create “candidate vaccines” within days, they still must be carefully tested in a rigorous process, first on animals and then on healthy volunteers, before being tested on a large scale on sick people. This takes months, if not years.
This process cannot be accelerated, as the occurrence of dangerous side effects can take time. So the work is colossal, but it is reassuring to see how quickly all the useful scientific data is now made available by different teams around the world.