قالب وردپرس درنا توس
Home / Health / Scientists say virus variants threaten pandemic

Scientists say virus variants threaten pandemic



For several weeks, emotions have been active in most parts of the United States. The number of coronavirus cases, hospitalizations and deaths has dropped sharply from a high point, and millions of people are receiving new vaccinations every day. Restaurants, shops and schools have reopened. Some states, such as Texas and Florida, have completely abandoned preventive measures.

The Americans have won the war against the coronavirus in a measurable way. Powerful vaccines and fast-deployed products can almost guarantee the eventual return to normal-return to the backyard for barbecue, summer camp and overnight.

However, it is becoming increasingly clear that the next few months will be painful. So-called mutations are spreading, carrying mutations, making coronaviruses more contagious and in some cases even more deadly.

Even though the vaccine was approved at the end of last year, paving the way for the end of the pandemic, the variant has raged in the UK, South Africa and Brazil. New versions keep coming-one week in California, the second week in New York and Oregon. When these new versions of the coronavirus are born, they may delay the end of the pandemic.

Currently, most vaccines seem to be effective against these variants. However, public health officials are deeply worried that future iterations of the virus may be more resistant to immune responses and require Americans to wait in line for regular rounds of booster injections or even new vaccines.

Devi Sridhar, a professor of public health at the University of Edinburgh in Scotland, said: “We have no momentum for development.” “This pathogen seems to be changing all the time, which makes it more difficult for us to suppress.”

Health officials acknowledged that as these new viruses spread within the United States, there is an urgent need to track these new viruses. B.1.1.7 has become a highly contagious variant that has caused a sensation in the United Kingdom and caused severe damage in continental Europe, but it has grown exponentially in the United States.

Limited genetic testing has found more than 12,500 cases, many of which are in Florida and Michigan. As of March 13, the variant accounted for approximately 27% of new cases nationwide, compared to only 1% in early February.

The Biden administration has pledged to provide a $200 million “down payment” to strengthen surveillance. This injection is designed to make it possible to analyze 25,000 patient samples a week for variants of the virus. This is an ambitious goal: in December, the country will only sequence a few hundred samples a week, and then by March 27, it can expand to about 9,000 samples a week.

Researchers say that until recently, the rise in B.1.1.7 has been overshadowed by the decline in infection rates for everyone, putting Americans in a false sense of security and leading to the premature relaxation of restrictions.

Sebastian Funk, professor of infectious disease dynamics at the London School of Hygiene and Tropical Medicine, said: “The best way to consider B.1.1.7 and other variants is to treat them as separate epidemics.” They all add up to provide a total number of cases, which really obscures this view.”

Other variants found in South Africa and Brazil, as well as certain versions of the virus first discovered in the United States, spread more slowly. But they are also worrying because they contain mutations that can weaken the effectiveness of the vaccine. Just this week, P.1 broke out. The variant destroyed Brazil and forced the closure of the Whistler Blackcomb ski resort in British Columbia.

Scientists say that the world is caught in a battle between vaccines and variants, and it will eventually win. But because every infection gives the coronavirus a chance for further development, vaccination in the United States and elsewhere must be carried out as soon as possible.

B.1.1.7 and other variants raise the infection to an uncertain level again. Earlier this week, Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, implored Americans to continue practicing cover-ups and social distancing, saying she felt “imminent death.”

She said: “We have too many places to look forward to-our position has great hope and potential, and there are many reasons for hope.” “But now I am scared.”

The coronavirus should have slowly transformed itself. Scientists said at the beginning of the pandemic that, like all viruses, it will absorb mutations and evolve into thousands of variants. But it will not change for many years-a stupid virus, some people call it.

The pathogen violated these predictions. “We expect the virus will change,” said Michael Diamond, a viral immunologist at Washington University in St. Louis. “We don’t expect it to happen quickly.”

Only when the variant is more infectious, causes more serious disease or weakens the immune response, you need to pay attention to the variant. The variants identified in the UK, South Africa, Brazil and California all meet the standard.

According to the latest estimates, B.1.1.7 is the first virus that has received widespread attention. Its infectivity is 60% higher than the original form of the virus, and its lethality is 67% higher.

Katrina Lisgow, an evolutionary biologist at the University of Oxford, said that the transmission method of the variant is no different from the original variant, but the infected people seem to carry more of the virus and spread for a longer period of time. She said: “Your infectiousness will last for more days.”

B.1.1.7 is extremely contagious, so that the United Kingdom has successfully curbed the infection only after strictly abiding by the three-month universal service requirement and an active vaccination plan. Even so, the rate of decline in cases has been much slower than during similar lockdown periods in March and April.

In continental Europe, the wave of B.1.1.7 cases that lasted for several months did not attract people’s attention under the agitation of increasing infections. The mutation wave is now at its peak.

Since mid-February, the daily rate of new cases in Poland has increased five-fold, forcing the closure of most public places. The number of receptions in Germany has doubled, so night gatherings in Berlin are forbidden.

In France, B.1.1.7 caused three-quarters of new infections, and some hospitals had to transfer coronavirus patients to Belgium to make room for beds. Compared with this period of a year ago, the approximate number of people who die of Covid-19 in Europe every day.

For a long time, government officials ignored this threat. Carl Pearson, a researcher at the London School of Hygiene and Tropical Medicine, said: “The situation may mask the emergence of new mutations.” “And the higher these plateaus, the more serious the problem.”

In the United States, coronavirus infections began to decline rapidly in January, prompting leaders of many countries to reopen and relax restrictions. But scientists have repeatedly warned that the decline will not continue. In mid-March, the daily fatality rate dropped to about 55,000, with 1,500 deaths a day, and some states (especially Michigan) began to show an upward trend.

Since then, the number of people nationwide has risen steadily. As of Saturday, the daily total is close to 69,000, and the weekly average is 19% higher than the figure two weeks ago.

Even with the decline in cases, researchers question the notion that vaccination is the cause. Millions of Americans are immunized every day, but even now, only 31% have received a single dose of the vaccine, and only 17% of the population are fully protected, making it easy for the vast majority of people Be infected.

Christian Anderson, a virologist at Scripps Research in San Diego, said: “The truth is that we are still in a position where there are not enough vaccinated people.” “If we are like Texas, say we are done. After Covid-19, then B.1.1.7 will appear and remind us that we are wrong. I have no doubt about it.”

This variant is particularly common in Florida, which lifted the restrictions and did not initially see a surge. Officials in other states used this as a reason for reopening. But now the infection rate in Florida is rising.

This change may simply be obscured by what scientists call seasonality. Sarah Bryant, an evolutionary biologist at the University of Chicago, said that respiratory infections are usually rare in the spring. Last summer, as the heat drove indoor personnel into the peak period of coronavirus infection, and this situation may reappear.

“I still don’t think we will get out of the predicament,” Dr. Kobe said of the entire country. “If we don’t have a wave again this spring, then I will be very, very worried about autumn.”

Although most vaccines are effective against B.1.1.7, researchers are increasingly concerned about other variants containing mutations called E484K. (Scientists often refer to it appropriately as “Eek”.)

This mutation has independently evolved in many variants around the world, showing that it provides a powerful survival advantage for the virus.

In laboratory studies, Pfizer-BioNTech and Moderna vaccines seem to be slightly less effective against B.1.351 (a variant found in South Africa). This variant contains the Eek mutation, which seems to allow the virus to partially evade the body’s immune response. The vaccines produced by Johnson & Johnson, AstraZeneca and Novavax are even less effective against B.1.351.

Jesse Bloom, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle, said: “I think E484K will be the most worrying mutation in the next two years.”

This mutation slightly changed the so-called spike protein on the surface of the coronavirus, making it difficult for antibodies to lock in and destroy the intruder.

The good news is that the virus seems to have only a few survival skills, which makes it easier for scientists to find and stop these defenses. Michel Nussenzweig, an immunologist at Rockefeller University in New York, said: “I am very satisfied with the fact that there are not many choices.”

The Eek mutation seems to be the main defense of the virus against the immune system. Researchers in South Africa recently reported that the new vaccine against B.1.351 should also protect against all other variants.

Pfizer, BioNTech, and Moderna are already testing a newly designed booster injection against B.1.351, which should be resistant to any variants known to weaken the immune response.

The head of the US, Dr. Anthony S. Fauci, said that it is not a replacement for a new vaccine against variants, but that it is equally effective for Americans to receive the Pfizer-BioNtech or Moderna vaccine for the third time within six months to a year. Institute of Allergy and Infectious Diseases.

He said this will keep the antibody levels of each recipient high and overwhelm any variant-a more practical strategy than making a specialized vaccine for each emerging variant.

Dr. Fauci said: “My only worry about chasing all the variants is that you will almost play Whac-A-Mole because they will keep appearing and keep appearing.”

Many scientists believe that the new coronavirus will exist in one form or another. As with the common cold coronavirus and flu, the country may spread multiple variants at the same time. Like the flu vaccine, keeping them out may require an annual injection.

The best way to prevent the emergence of dangerous variants is to immediately reduce the number of cases and provide immunizations for most parts of the world (not only the United States). If most parts of the world remain unprotected, the virus will continue to evolve in dangerous new ways.

Rosalind Egg, an epidemiologist at the London School of Hygiene and Tropical Medicine, said: “This may be something we have to deal with for a long time.”

She added: “Even if changes happen again, this is likely to happen, but compared to a year ago, we are in a better and stronger position to deal with this problem.”


Source link