Delta mutant strains making it more difficult to achieve herd immunity?

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Delta mutant strains making it more difficult to achieve herd immunity?

Delta mutant strains are prone to cause secondary infections, making it more difficult to achieve herd immunity?

On October 15th, the world’s authoritative academic journal Science published a blockbuster article on the COVID-19.

The article studied the COVID-19 epidemic cases that broke out in India this year and pointed out that in the face of the COVID-19 virus Delta variant, if you want to It is very difficult to generate herd immunity, because mutant viruses may be more likely to cause secondary infections.

The study pointed out that in 2020, New Delhi, the capital of India, experienced multiple outbreaks of COVID-19 pneumonia. By 2021, the seroprevalence rate of the population reached more than 50%. However, in April 2021, due to the emergence of delta mutant strains, this The number of cases has skyrocketed.

Data show that the number of new cases in New Delhi increased extremely rapidly in April. From March 31 to April 16, the number of new cases per day increased from about 2,000 to 20,000, and this increase was mainly due to Del Caused by a mutant strain of the tower.

The combined results of epidemiology, genetics, and mathematical models show that although there have been many types of strains circulating locally before, the emergence of Delta quickly replaced other strains and became the most prevalent strain.

Not only that, the transmission power of the Delta variant is 30-70% higher than the earlier epidemic of the COVID-19 virus. What’s more frightening is that even if you have been infected with the COVID-19 in the early stage, the human immunity can only bring 50-90% protection to the Delta variant.

Therefore, the researchers believe that although a sufficient seroprevalence rate or a moderately high vaccination level was previously considered to be immune to the new coronavirus, the delta variant can trigger a rapid outbreak in people who have an immune response to the previous variant. , Resulting in re-infection and breakthrough infection by vaccination. Therefore, it is not easy to form a similar herd immunity.

In fact, as early as August this year, the Infectious Diseases Society of America (IDSA) issued a briefing showing that the spread of the delta variant of the new coronavirus has increased the proportion of the population required to achieve herd immunity to 80%, or even close to 90%.

Richard Franco, an assistant professor at the University of Alabama at Birmingham, said at the briefing session that day that the delta mutant strain is “a very dangerous virus, much more dangerous than the original strain.”

The infectivity is twice that of the original species, so the proportion of the population required to achieve herd immunity is much higher than the previously estimated 60%-70%, reaching 80%, or even close to 90%.

As for Delta virus, it is more likely to cause secondary infection. The world-renowned authoritative journal “Nature” published twice on July 21 and 28 to introduce the danger of this strain.

Among them, the article on the 28th pointed out that the S protein of the Delta variant has more mutations than other variants, which improves the binding ability of the S protein to the receptor on the cell membrane and strengthens the virus’s ability to evade the immune system.

But you don’t need to panic too much. As long as you strictly abide by our country’s current prevention and control measures, you don’t need to worry too much. It should be clear that vaccination is still the most effective way to prevent the new coronavirus.

Therefore, in order to prevent the COVID-19, vaccination and Personal protection measures such as wearing masks and washing hands frequently are still indispensable.