What is COVID-19 herd immunity?

Health authorities around the world are competing to vaccinate enough people to stop the spread of COVID-19, but what is considered “sufficient” remains an open question.

The goal is to reach “herd immunity”. This means that a sufficient number of people from either vaccination or past infections are immune and prevent uncontrolled spread.

Herd immunity does not immunize anyone, and the outbreak can still burn. This means that the virus will not easily fly from person to person and will help protect people who are vulnerable to catching the virus.

What is known about viruses and herd immunity is:

What is herd immunity? Does it work with COVID-19?

Herd immunity is when a sufficient number of people are immune to the virus and the virus cannot spread easily. This makes it less likely that the virus will jump from person to person and reach people who have not yet been infected.

People can gain immunity to certain viruses after they have survived the infection or have been vaccinated. Generally, at least 70% of the population must be immune to achieve herd immunity. However, the duration of immunity depends on the virus, and it is not yet known how long COVID-19 survivors will have that protection.

How long does it take for herd immunity to develop in the United States?

More than 150 million Americans (about 57% of the adult population) have been vaccinated at least once, but government leaders from the Biden administration to the city and county levels remain in the rest of the country. Get inoculated.

The Byden administration wants 70% of adult Americans to be vaccinated by July 4, but vaccinations are declining and people who doubt the effectiveness of the vaccine or simply get vaccinated. We acknowledge the challenge of winning those who don’t want to.

How is the herd immunity threshold calculated?

This is a formula based on the infectivity of the virus, or the number of people who catch the virus from an average of one infected person.

However, this calculation only provides a wide range of goals when spreads can drop significantly. This number may vary by region.

Dr. Walter Orenstein, an infectious disease expert at Emory University, said:

Orenstein states that other factors that influence the level and spread of vaccination can vary within cities.

How long does it take for herd immunity to develop in the United States?

How can I know that I have reached herd immunity?

Ashley St. John, who studies the immune system at Duke-NUS Medical College in Singapore, said evidence that we are approaching herd immunity would be “a disruption to the chain of infection.”

But we don’t have to wait for the big declaration that we have reached that milestone.

To decide whether to relax the restrictions, health authorities will monitor infection and hospitalization trends as vaccinations are deployed. And these decisions, which can begin long before the ideal herd immunity threshold is reached, are gradual and region-specific.

How do coronavirus mutants affect herd immunity?

It depends on the protection that past infections or vaccinations give you from mutants.

If the vaccine turns out to be significantly less effective against the mutant, more parts of the population will need to be vaccinated. Renewal of existing vaccine To make them more effective, Orenstein said.

So far, Shot seems to provide at least some protection from the most annoying variants. But scientists are still studying the situation and are worried about further mutations.

The variants emphasize the importance of immunizing people as soon as possible. Delaying infection is very important because the virus can mutate when it infects humans.

Does herd immunity need to be global?

Global herd immunity is ideal, but unlikely.

Rich countries have booked most of the vaccines produced this year. In the United States, for example, officials say enough people could be vaccinated and begin to return to normal by the fall.

But many poor countries are probably I have to wait longer..This is why the World Health Organization has caveat Its global herd immunity is unlikely to be achieved this year.

Different countries have different levels of vaccination, which is also why many experts believe that the virus will not be completely eliminated.

Can herd immunity decline?

Experts believe it will take at least a few months, but the duration of immunity after vaccination or due to infection is unknown.

Still, booster shots may be needed in the future. Also, the current COVID-19 vaccine is expected to work in variants identified in the UK and elsewhere, but over time the virus may mutate well and need to update shots. there is.

For example, influenza virus mutations are the reason for being vaccinated against influenza each year. However, experts point out that coronaviruses generally do not mutate so easily.

What if the COVID-19 vaccine does not prevent infection?

The currently deployed COVID-19 vaccine appears to be very effective in preventing people from getting sick. we I don’t know yet You can see how good it is to completely stop the infection, but it should help significantly reduce the spread of the virus.

This is because the vaccine prevents the virus from multiplying in the body. Deborah Fuller, a vaccination expert at the University of Washington, said the body should release less virus in a shorter amount of time, even if infected after vaccination.

Immunizing as many people as possible is another key reason to end a pandemic.

The Associated Press’s Department of Health Sciences is supported by the Department of Science Education at the Howard Hughes Medical Institute. AP is solely responsible for all content.