Humans lose ground in the fight against ever-changing viruses

July 22, 2021-A year ago, scientists are looking at the future of COVID-19 Pandemic I felt optimistic. vaccine Development was expanding towards unprecedented results.And unlike the virus that causes it influenza Or AIDS, They thought the virus could not be mutated to avoid fully primed humans Immune system..

“Thankfully, SARS-CoV-2 doesn’t seem to have evolved such a trick yet. This means that by pursuing something relatively simple, we still have the opportunity to stop its spread and pandemic. Suggests. vaccine “Approach.” July 31, 2020, essay for New York Times..

It was around that time.

Since then, the UK, South Africa, India and Brazil have all discovered “variant of concern”. This is a mutant strain that can spread more easily and cause more serious illness.

Block’s new kid, Delta variant The first to be detected in India appears to be much more contagious than the original cousin. It is rapidly becoming a major source of new COVID-19 cases everywhere, causing an increase in new cases, even if the majority of the population is vaccinated.

At the same time, efforts to vaccinate the world have hit very serious barriers, and hopes of extinguishing the virus in this way have rapidly diminished.

Amalio Telenti, MD, Chief Data Scientist at Vir Biotechnology, based in San Francisco, said:..

Vaccines are a high hurdle to viruses

This does not mean that the death toll of COVID-19 will continue to increase indefinitely or even reach the height of last winter.The virus has not yet developed the ability to completely escape the immune response stimulated by the best of the present. vaccine..

“The data confirm that at least the mRNA vaccines (Pfizer and Moderna) work well against delta mutants,” said Ravina Kullar of PharmaD, an infectious disease specialist and epidemiologist at UCLA. Says...

But that means that humanity is facing a foreseeable future battle.

From the beginning, epidemiologists said,Herd immunity, “Sufficient people have been vaccinated and the virus is unable to find enough new hosts to continue replicating. This can occur spontaneously if a sufficient number of people are infected or vaccinated.

At the beginning of the pandemic, a handful of scientists argued that allowing widespread infection provided the fastest option to contain the virus through nature. Immunity.. The approach was quickly criticized as epidemiologists calculated the resulting millions of deaths.

And there is no natural guarantee Immunity You can knock out the virus.Often, the virus evolves to evade the immune response and reinfects more people until a new outbreak occurs. Immunity.. This creates a wave of transmission that declines and flows over time, as it does with the flu.

Vaccination provides a slower but much safer approach to crushing the virus.that is smallpoxIt was eradicated worldwide in 1980, after decades of global vaccination efforts. In addition, vaccination may be more effective than innate immunity.This seems to be the case Coronavirus..

It comes down to math

However, so far, humans have not been able to eradicate other viruses by vaccination other than smallpox. The success of such efforts depends on multiple factors, including the effectiveness of the vaccine and other health measures, such as in the case of the coronavirus. Avoid crowds And masking.

The competition between viral evolution and human vaccination is summarized in a mathematical problem. On average, everyone infected with the original coronavirus in Wuhan, China, infected the other 2.5. Epidemiologists have calculated that vaccination of 70% of the population could reduce the number of new people infected and reduce the virus.

In contrast, people infected with the delta variant appear to be infected with more people. 3.5 To Seven A new infectious disease. This raises the standard of herd immunity to 85% of the population.

Immunization efforts at this time appear unlikely to reach that level.In many countries where vaccines are widely available, the rate of new vaccinations is collapsed, It is behind schedule to reach the original target of 70%.

At current rates, the United States will not reach that target until December.But 11% To 14% Many Americans say they don’t want to be vaccinated if they have the option.Add to Ten% Those who want to “wait and see”, and herd immunity in the United States, seem out of reach.

In some low-income countries, the outlook for herd immunity looks even further. 1% of the population I have been vaccinated so far.

So why did scientists think that herd immunity was ever possible? The first photo of the coronavirus suggested a virus that evolved only slowly.

Coronaviruses have the ability to calibrate genetic material as they replicate. This makes it less likely to mutate than many other viruses. And the virus was under little evolutionary pressure, as it had many fresh, non-immune victims.

However, as the virus spreads and encounters more and more people and more and more immune responses, mutations are more likely to occur. “If you put it in hundreds of millions of people, more variations will arrive,” says Dr. John P. Moore, a professor of microbiology and immunology at Weil Cornell Medicine in New York City...

Some scientists believe that the virus will never change enough to completely escape the immunity produced by the vaccine. These vaccines stimulate antibodies that attack some of the spikes that the virus uses to latch into host cells. In the most contagious variants, including Delta, the virus modifies some of the spikes, making them less susceptible to antibodies.

Their effectiveness remains strong, as the vaccine still stimulates antibodies that attack the rest of the spike. Vaccines also stimulate cell-mediated immunity. This is the process by which immune cells destroy infected cells before they release the virus.

Pauline Vetter, MD, MD, an infectious disease specialist at the University Hospital of Geneva, Switzerland, says there is increasing evidence that this natural immune process works against mutants.

Additional vaccines, booster shots with improved prescriptions, and even entirely new types of vaccines are all under study.

Can you see the finish line?

Can the virus hit an evolutionary dead end?

“Peplomer cannot be mutated indefinitely without loss of function,” Moore said. “They aren’t infinitely plastic. Still, you can imagine some variants that might be worse.”

The complex interaction of these factors with other factors, such as the persistence of the immune response, makes it difficult to predict the future of a pandemic.

However, most experts believe that it will never go away.To Survey of 119 immunologists By nature, 89% said they expected the virus to become endemic and that it “continues to circulate in the pockets of the world’s population.”

As such, it can resemble influenza, perhaps increasing or decreasing with the seasons, worsening in one year and better in another as both the virus and its defenses evolve.

In some parts of the world, vaccination can approach herd immunity. In the United States, it can mean the entire state, or perhaps a city. “We don’t intend to have national herd immunity, but it’s probably close to herd immunity in important parts of the country,” Moore said. “I live in Manhattan. Life is pretty normal.”

Meanwhile, in Los Angeles, Kullar has warned that mortality is rising again, and local health officials require that even vaccinated people wear masks in public places.

“I think we need to keep in mind that the pandemic isn’t over yet,” she said.