Viral load of the delta variant 1,000 times higher than the original coronavirus strain

BEIJING – The fast-spreading delta variant of the new coronavirus has been gaining traction around the world since it was first detected in India, and researchers can now get an idea of ​​why: Its viral load is 1,000 times higher than the original strain of the virus.

The delta variant is a mutated version of the new coronavirus that spreads more easily than other strains. It now accounts for about 83% of COVID-19 cases in the United States, as it continues to increase largely among unvaccinated populations, officials said.

Viruses are constantly mutating and most of the changes are not of concern. But there are fears that some variants may evolve enough to be more contagious, cause more serious disease, or escape the protection offered by vaccines.

A recent study published on July 7 and led by Chinese epidemiologist Jing Lu at the Guangdong Provincial Center for Disease Control and Prevention in Guangzhou, China, shed light on why the delta variant is of serious concern to the system. global health and why it is more transmissible than other mutations.

Why is the delta variant more contagious?

The study authors noted that one feature that makes the variant so worrisome is its high viral load.

Researchers have found that the delta variant contains 1,000 times more viral material than that of the original new variant of the coronavirus that infected large parts of the world’s population at the start of the global pandemic last year.

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This means that the delta variant can replicate at a much faster rate than the original strain, making the mutation much more infectious, according to the study.

When a person is infected with the delta variant, the mutation releases much more viral material, making it harder to remove and easier to infect others.

The researchers also found that, on average, it took about four days for the delta variant to reach detectable levels using a standard COVID-19 test kit, compared to the six days it took for the original coronavirus strain to be detected.

Experts believe that the delta variant spreads more easily due to mutations that allow it to attach better to cells in the human body. On its website, the US Centers for Disease Control and Prevention notes “increased transmissibility” with the delta variant and the possibility that it may make some monoclonal antibody treatments less effective.

Is the Delta variant more deadly?

It is not yet clear whether the variant is making people sicker as more data needs to be collected, told The Associated Press Dr Jacob John, who studies viruses at Christian Medical College in Vellore in southern London. ‘India.

Regardless, many health experts have warned of the variant’s potential to delay progress in the pandemic. The World Health Organization has said the delta variant is “the fastest and fittest” of the known coronavirus strains and has warned that it will “kill” the more vulnerable “more effectively” than previous strains.

“All of these viruses have been fatal to themselves,” Dr Michael Ryan, executive director of the WHO’s health emergency program, said at a press conference on June 21. “This virus has the potential to be more deadly as it spreads more efficiently between humans and it will eventually find vulnerable people who will become seriously ill, need hospitalization and potentially die.”

Dr Anthony Fauci, the nation’s foremost infectious disease expert, also called the delta variant “currently the greatest threat in the United States to our attempt to eliminate COVID-19.”

Should I be concerned about the delta variant if I am vaccinated?

Earlier this month, Dr.Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, said the three COVID-19 vaccines approved for emergency use by the FDA – Pfizer, Moderna and Johnson & Johnson – are effective against Delta a variant.

“The world is understandably worried about the variant of the delta virus,” Fauci said. “The vaccines are indeed effective against it.”

RELATED: Study: J&J COVID-19 vaccine significantly less effective against delta variant

But a study published July 19 on the website of the medical journal BioRxiv found that the single-dose Johnson & Johnson vaccine was significantly less effective against the highly transmissible delta and lambda variants compared to the two-dose vaccines from Pfizer and Moderna. .

The study authors found that while the two-dose vaccines were 94-95% effective in preventing COVID-19, the J&J vaccine was only 66.9% effective “in preventing moderate to moderate illness. severe “.

The study authors said that if there was still a trend for breakthrough infections accompanied by severe illness caused by the novel coronavirus, the millions of people who were inoculated with the J&J vaccine might consider a booster to to increase protection against variants of concern.

The study authors also said that while there is currently not enough evidence to support the need for a booster, the medical community should focus on primary vaccination efforts in the United States and in the world.

The new study has not yet been peer reviewed and is based on laboratory experiments.

“The message we wanted to get across was not that people shouldn’t get the J&J vaccine, but we hope that in the future it will be boosted with another dose of J&J or a boost with Pfizer or Moderna.” , Nathaniel Landau, lead author of the study, told The New York Times.

Earlier this month, Johnson & Johnson announced that their vaccine was effective against the highly contagious delta variant, even eight months after inoculation.

“We believe our vaccine provides long-lasting protection against COVID-19 and triggers neutralizing activity against the Delta variant. This adds to the strong body of clinical data supporting the ability of our single injection vaccine to protect against several variants of concern, ”Payul Stoffels, Chief Scientific Officer of Johnson & Johnson said in a July 1 press release.

Recent findings on the J&J vaccine are consistent with medical observations on the resistance of the delta coronavirus variant to other vaccines. In a study published in The Lancet on June 14, researchers observed both vaccinated and unvaccinated patients who tested positive for COVID-19 between April 1 and June 6, 2021 in Scotland, where the delta variant became dominant.

Pfizer’s vaccine “offered very good protection: 92% (95% CI 90-93) S gene negative, 79% (75–82) S positive gene. The protection associated with ChAdOx1 nCoV-19 (Oxford-AstraZeneca vaccine) was however substantial but reduced: 73% (95% CI 66-78) for S gene-negative cases versus 60% (53-66) for those S positive gene “, according to The Lancet.

The study authors noted that more research needs to be done for more precise percentage estimates on the effectiveness of the two vaccines.

Do I have to wear a mask if I am vaccinated?

Despite the increase in COVID-19 cases in the United States, the CDC said on Thursday it was not likely to reimpose its policy of recommending masks for everyone “at this time.”

In May, the CDC released guidelines that people vaccinated could dispense with masks in most settings. They are always needed in places like planes, buses, and trains.

U.S. Centers for Disease Control and Prevention director Dr Rochelle Walensky said Thursday she feared the increase in cases would soon overwhelm the nation’s health care system, but assured Americans that vaccines were still the best defense against the highly contagious Delta variant.

“If you are not vaccinated, you absolutely must wear a mask. If you are vaccinated, you have exceptional levels of protection against the vaccine, and you can choose to add an extra layer of protection by putting on your mask, and it’s a very individual choice. It’s been consistent with our CDC focus since we released it, “Walensky said.

RELATED: Fauci: CDC ‘carefully considering’ advice on masks for schools

The American Academy of Pediatrics this week recommended universal masking in schools, even for those who are vaccinated against the virus that causes COVID-19. In response, Dr Anthony Fauci said the academy wanted to “go the extra mile” to make sure children are protected, but said the US Centers for Disease Control and Prevention was monitoring the situation closely. .

Fauci told “CBS This Morning” on Tuesday that the advice is being overly cautious due to the increase in cases blamed on the delta variant of the coronavirus.

This story was reported from Los Angeles. Jordan Smith, Kelly Hayes and The Associated Press have contributed.