Health officials around the world are rushing to vaccinate enough people to stop the spread of COVID-19, but what qualifies as “enough” is still an open question.
The goal is to achieve ‘herd immunity’, that is when enough people have immunity, whether against vaccination or an infection in the past, to stop uncontrolled spread.
Herd immunity does not make anyone immune, and outbreaks can still flare up. This means that a virus no longer easily jumps from person to person, and it helps to protect those who are still vulnerable.
No one knows for sure what the herd immunity threshold for the coronavirus is, although many experts believe it is 70% or higher. And the rise of variants further complicates the picture.
Here’s what’s known about the virus and herd immunity.
HOW IS THE HERD CALCULATED IMMUNITY DRINK?
This is a formula based on how infected a virus is – or how many people get the virus from one infected person on average.
But the calculation provides only a broad target for a large decrease in distribution. The figure may also differ by region.
“It’s not 64.9, and 70.1 is fantastic,” said dr. Walter Orenstein, an expert in infectious diseases at Emory University, said.
Orenstein notes that vaccination levels and other factors that affect distribution can vary even within a city.
HOW DO WE KNOW that we have achieved herd immunity?
Proving that approaching herd immunity would be a “disruption in the distribution chain”, Ashley St. said. John said, who is studying the immune system at Duke-NUS Medical School in Singapore.
But do not wait for any big statement that we have reached the milestone.
To determine if restrictions are relaxed, health officials will monitor infection and hospitalization trends as vaccinations begin. And these decisions are likely to start long before the ideal herd immunity threshold is reached, although this will be gradual and will vary by region.
In India, for example, scientists believe that more people in cities with densely populated cities, where the virus spreads faster, will need to be protected than in the vast countryside.
India plans to search nationwide for antibodies to find out what percentage of its nearly 1.4 billion people are already infected, Dr. Jayaprakash Muliyil said. He advises the government on virus surveillance.
Vaccination of the vaccine also plays a role. Fewer people need to be vaccinated to bring out herd immunity if the shots work higher.
HOW DOES CORONAVIRUS AFFECT VARIOUS HERD IMMUNITY?
It depends on the protection that infection or vaccination provides in the past against the variant.
If vaccines were to prove particularly less effective against a variant, an even larger part of the population would have to be vaccinated or existing vaccines would have to be updated. to make them more effective, Orenstein said.
So far, it appears that the surveys offer at least some protection against the most worrying variants. But scientists are still studying the situation and are worried about further mutations.
The variants emphasized the importance of vaccinating people as quickly as possible. Delayed transmission is critical as viruses can mutate when they infect humans.
SHOULD HERD IMMUNITY BE GENERAL?
Global herd immunity is ideal but unlikely.
Rich countries have reserved the most vaccines produced this year. In the US, for example, officials said that enough people could be vaccinated by the fall to get back to normal.
But many poorer countries will probably have to wait longer. This is why the World Health Organization has warned that global herd immunity is unlikely to be achieved this year.
Differences in vaccination levels between countries are also the reason why many experts believe that the virus can never be completely eradicated.
CAN SHEPHERD IMMUNITY DEMOLIT?
It is not known how long immunity lasts, whether after vaccination or against an infection, although experts believe it should last at least a few months.
Still, shots on the road may be needed. And while current COVID-19 vaccines are expected to work on the variants identified in the UK and elsewhere, it is possible that the virus may mutate enough over time to keep the shots up to date.
Mutations in flu viruses, for example, are the reason we get flu shots every year. But experts note that coronaviruses usually do not mutate as easily.
WHAT IF THE COVID-19 BOSSENTS DO NOT PREVENT INFECTION?
The COVID-19 vaccines now seem very effective in preventing people from getting sick. We do not know yet how good they are at stopping the infection completely, but it should help reduce the spread of the virus a lot.
This is because the vaccines prevent the virus from multiplying in your body. So, even if you get infected after vaccination, your body needs to shed fewer viruses and for a shorter period of time, said Deborah Fuller, a vaccination expert at the University of Washington.
This is another reason why as many people as possible are vaccinated, the key to ending the pandemic.
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