Corona puzzles .. Is there a small amount of virus left in the body, and why have infections declined in Japan?

With more good news coming in about the control of the emerging corona virus "Covid-19" pandemic, there are mysteries that we still cannot solve, so what are they?

We start with the good news, which is the registration of deaths due to "Covid-19", the lowest level in the world in 11 months, according to the French press agency.

And 53,245 deaths were counted between Monday, September 27 and Sunday, October 3, at a rate of 7,606 deaths per day, at a time when the global toll of the “Covid-19” epidemic continues to decline since the end of August, after it reached its maximum for a short period, recording a rate 10,000 deaths a day.

The number of weekly deaths decreased by about a quarter (24%) within a month.

At the beginning of November 2020, 50,000 deaths were counted within a week, before the toll quickly exceeded this limit in the last week of January, registering the highest weekly count.

After a year of fluctuations in the outbreak of the epidemic due to the spread of mutant (new strains), especially the highly contagious delta mutant, the number of new infections also recorded a decline of nearly a third from what it was at the end of August.

Now let's move on to the puzzles:

The first riddle: How did Corona originate?

As the world approaches two years since the first infection with the Corona virus was reported in the Chinese city of Wuhan, we still do not know much about its origin, according to a report on the axios website.

Axios quoted the Wall Street Journal that the World Health Organization had re-launched its investigation into the origin of the pandemic, which had been stalled, while a separate academic working group also looking into the origin of Corona was dissolved due to concerns about bias.

So far, there is no evidence for the validity of either of the two main theories about the origin of the pandemic. One theory says that “Covid-19” appeared in animals before it was transmitted to humans, while the second says that it arose from laboratory work at the Wuhan Institute of Virology in China.

Science magazine held a round table in which scientists from both sides participated to discuss the topic.

The main problem, says Jesse Bloom, an evolutionary biologist at the Fred Hutchinson Cancer Center, is that "we can't really pinpoint how the virus got to Wuhan, and there is no high or natural spread of viruses closely related to SARS-CoV-2." "Cove-2" - the scientific name for the Corona virus - (SARS-CoV-2) in Wuhan".

Bloom said that given the aforementioned fact, in addition to another fact that the Wuhan Institute of Virology was working on samples taken from bats that are at high risk for harboring coronaviruses similar to “SARS-Cove-2” “that is why I still believe that a leak occurred in the laboratory.” It's very likely."

Michael Woroby, an evolutionary biologist at the University of Arizona argues that there are "many opportunities for other non-research activities to bring these viruses" to Wuhan, such as the wildlife trade in China.

Linfa Wang, a professor at Duke-NUS Medical School in Singapore, believes that political differences between the United States and China have made it difficult to fairly judge the origin of the virus.

The second puzzle: How long will the disease "Long Covid" last?

Does a small amount of corona virus remain in the body and cause long covid?

The Covid crisis threatens to infect some patients with the so-called “long Covid” whose symptoms remain visible for months, and although doctors know more about it today, there is still mystery surrounding its true nature.

"More research should be done on long-term Covid disease and patients with it," Swiss doctor Maysam Nehme said during a conference organized by the Pasteur Institute at the end of September.

Like many other researchers around the world, the doctor is working to give a better definition of long-term Covid disease, which is the persistence of symptoms in a patient who was infected months ago with the virus that causes Covid-19.

Following the onset of the health crisis in 2020, many patients reported that after a long period of illness they still suffer from symptoms such as fatigue, difficulty breathing and permanent loss of sense of smell.

Today, there is a consensus that this phenomenon exists.

Most researchers and many health authorities recognize that long-term symptoms persist in some patients, including those with mild forms of Covid.

After studying several hundred patients, Nehme estimated that more than a third of them continue to have at least one symptom 7, 8 or 9 months after the injury.

But this is only a starting point, it is not known what can cause these symptoms to persist: does a small amount of the virus remain in the body?

And does the damage it causes to some parts of the body persist, whether the damage is related to the virus itself or the immune reaction?

Then is there a purely psychological component?

But the question about the causes leads to another question: is there one long covid or do we classify under the same term different facts, between patients with mild forms of covid and others who have developed complications that required hospitalization or even placement in intensive care?

The third puzzle: Do children get long-term Covid?

One particularly sensitive question arises: What is the threat to children from the long-term COVID-19 disease?

Answering it could change the way we understand the urgent need to vaccinate young children, who are at virtually no risk of contracting a severe form of Covid, but the long form of the disease can be disabling.

Here, too, some researchers warn of panic.

An analysis published at the end of September in the Journal of Pediatric Infectious Diseases, based on about 15 previous studies, estimated that these studies often suffer from bias and amplify the prolonged frequency of COVID-19 in younger people.

One of the lead authors, pediatric researcher Nigel Curtis, wrote on Twitter: "The real risk is probably closer to 1 in 100, versus the often cited figure of 1 in 7."

But he mentions that this percentage, although it seems small, represents many cases and requires thinking about how to deal with them properly.

 The fourth puzzle: Why did Corona injuries decline in Japan?

This conundrum is recent, as the number of coronavirus infections in Japan has fallen to its lowest level in nearly a year while other countries in Asia are grappling with rising infections, leaving health experts baffled.

New daily cases in Tokyo fell to 87 on Monday, the lowest since November 2 last year, a sharp drop from more than 5,000 cases per day during the August wave that damaged the capital's medical infrastructure.

Infections have also decreased across Japan.

After a slow start, Japan has made rapid progress in its vaccination campaign, and social distancing restrictions imposed for about 6 months may have helped curb the spread of the virus.

Yet the speed with which the wave of infections caused by the highly contagious delta variant has subsided has baffled experts.

Hiroshi Nishiura of Kyoto University is among those who believe that the summer rise in cases is mainly due to trends in human activity.

He said the infection was linked to the holidays.

"During the holidays we meet people we rarely meet," Nishiura, one of the top infectious disease experts who advises the government, told Reuters.

He stressed that the significant rises in infections in South Korea and Singapore may be linked to some mid-year holidays, and the convergence of Asian and Western holidays at the end of the year could lead to a "nightmare."