Kill everyone on the planet.

This is my first assignment for students in the public health class, and it is full of good people who are passionate about saving the world.Their homework is Play a game called the plagueThey pretend to be pathogens and strive to infect everyone in the world before humans can develop treatments or vaccines.

Why do you want to do this assignment?Because as Professor of Epidemiology of Infectious Diseases, My goal is to teach students to think like pathogens so that they can learn how to control pathogens.

With COVID-19, thinking like a pathogen will lead to an inevitable conclusion: Distributing the vaccine to everyone in the world as soon as possible is not only a moral imperative, but also selfish.

Passing genetic material is the key goal

Although a lot Rich country Vaccines will be provided for the entire population soon, Poorer countries It may take several years to shoot.About half of U.S. residents now have at least Partial vaccination. Many other countries have not yet reached 1% Vaccination rate.

During this period, SARS-CoV-2 will take advantage of this open opportunity.

In fact, pathogens don’t actually want to kill all human hosts, because they will eventually have nowhere to survive. Their goal is to pass on genetic material to the next generation. They will do their best to answer their call for evolution.

Virus to-do list

Of course, viruses and bacteria don’t have brains, so they don’t “think” themselves.But like all life forms, these special creatures try to Maximum reproduction And let their offspring survive and reproduce.

As a single virus particle, you have two key items on the to-do list. First, you need a place to spread. You need to multiply yourself to increase a child’s chances of doing the right thing and providing you with a grandchild. As a virus, you are very good at this. No need to visit Tinder and find the perfect match because you can reproduce asexually.Instead, you use Your host’s cellular machinery -The person you infect-reproduce yourself.

Second, you need a method from the current host to the next host that will be infected, also known as transfer. To do this, you need to exit the portal (the way to exit the current host) and enter the portal (the way to enter the next host). You need a host that is vulnerable to infection. And, you need a way to go to the next host.

Susceptible host? When SARS-CoV-2 first appeared, it was easy. Because it is a new type of pathogen, the entire global population is vulnerable to infection. No one has complete immunity to this particular virus, because this virus does not exist in humans before 2019. Now, every time a person is exposed or vaccinated, the number of susceptible hosts is decreasing.

For one Export portalThere are several options for SARS-CoV-2-mainly through breathing to exhale, but also through stool and other body fluids to exhale. For the entrance portal, it has an inhalation function-the new host inhales it-and to a lesser extent is ingested-the new host consumes it orally.

This means that the spread of the virus is relatively easy, involving an activity that people of all ages do all day: breathing. Other viruses require more specific activities or conditions, such as sharing needles for sexual intercourse or HIV, or being bitten by a specific species of Zika virus.

SARS-CoV-2 is a smart virus

In addition to dissatisfying the global population, SARS-CoV-2 also played many roles. Several other features made it particularly successful.

First, although it does kill, it can also cause mild or asymptomatic infection In others. When pathogens kill most hosts, their spread is less successful because humans change their behavior based on the perceived threat of disease.

Ebola virus Is a perfect example. If college students think this might cause them to bleed like an eye, like some people infected with Ebola, then college students are more likely to cancel their spring break plans to Florida in 2020.

The incubation period of SARS-CoV-2 is also very long, that is, the time from infecting a new host to the appearance of host symptoms. However, it can spread in the time before the symptoms appear, which allows it to spread undetected.

Bigger transmission, more new variants

If you think about the SARS-CoV-2 pathogen now, you are frantically looking for a solution to the current vaccine formulation. The more cases you cause, the more likely you are to break through new variants of the vaccine. You don’t care whether these cases occurred in Montana or Mumbai. This is why no one can be immune to the pandemic until the spread is controlled on a large scale.

Thinking like a pathogen needs to consider the time scale of evolution. For viruses, this is very short, sometimes a process of human infection. SARS-CoV-2 and other viruses have an amazing ability to adapt to changing conditions.

One of their survival strategies is an inherent error in the reproduction mechanism that leads to mutation. Sometimes mutations occur, thereby improving the ability of the virus to survive and spread.

This led to the new Variants, Just like those we have seen recently.So far, there are vaccines Appears effective Oppose variants. However, the new variants may reduce the effectiveness of the vaccine or cause the need for booster injections.The increased deliverability of new variants may have given people a chance to achieve Herd immunity Through unreachable vaccinations.

We watched in horror The virus ravages India, For some people, this seems to be an unreachable threat. However, each new case provides another opportunity for the emergence and spread of new variants around the world.

To make the virus smarter, we need to shoot everywhere

This is why global access to vaccines is not only a moral imperative, but also the only way to make the virus smarter. Even if we step up vaccination here, the United States can now do a lot to ensure global access to vaccines.

The U.S. has proposed Substantive commitment to Kovacs, This is a global cooperation aimed at accelerating the development and production of COVID-19 vaccines and ensuring fair distribution.

The United States can now raise more funds and force other countries to do the same.funds The promise to COVAX may be hollow In the absence of a simultaneous plan to quickly distribute vaccine stocks, the United States had already accumulated this vaccine when the United States raced to buy the first batch of available vaccines.

In addition to vaccinations, the United States and other resource-rich countries can also help increase Usability of the test In all countries/regions.These countries can also provide technical and logistical assistance to improve the promotion of vaccines, and work to coordinate and improve global Genome monitoring Therefore, new variants can be quickly discovered.

If all this seems expensive, consider the huge economic cost of reinvesting in lock-in. There is no cheap time now.

In order to avoid compromising the effectiveness of the millions of shootings in the weapons of the rich countries, we must shoot the weapons into the arms of the people of all countries.

Karen Levy, Associate Professor of Environmental and Occupational Health Sciences, Washington University

The article was republished on conversation Under the Creative Commons license.read Source article.