The latest news on vaccine efficacy and the delta variant

As the fifth wave of COVID-19 induced by the Japan Delta subsides and the inoculation campaign continues, scientists continue to collect more data on the vaccines and their effectiveness against the highly contagious variant.

While vaccines do not offer 100% protection against delta, or any other form of virus, public health experts have repeatedly found COVID-19 injections to be effective in preventing hospitalizations and visits. to emergency services.

Here are some key questions and answers regarding COVID-19 injections and the delta variant:

Why is inoculation essential in the fight against delta?

Delta is considered to be more than twice as contagious as the strains that prevailed at the start of the pandemic. Some research suggests that the delta could cause more serious illness in unvaccinated people than other variants. The U.S. Centers for Disease Control and Prevention (CDC) said the risk of infection is eight times higher in unvaccinated than in vaccinated, and the risk of hospitalization or death is 25 times higher.

Over the summer, the SARS-CoV-2 delta mutation took over in Japan and many other parts of the world.

As of September 15, Japan had 20,901 nationally confirmed delta infections after a peak of 5,238 cases in the week of August 30 to September 6. However, officially reported figures would only reflect a portion of the number of infections as not all viral samples are screened for all variants.

The delta variant is also responsible for over 98% of new coronavirus infections in the United States. A high delta infection rate naturally raises concerns about the effectiveness of existing vaccines and treatments, especially given the higher viral load seen with delta infections.

A recent pre-printed study by researchers at the Chinese Academy of Medical Sciences also found that viral loads in delta infections are around 1,000 times higher than those caused by other strains of SARS-CoV-2. . Therefore, as the World Health Organization warns, a higher level of antibody is needed to overcome delta compared to other variants like alpha. WHO experts have stressed that being fully vaccinated is essential for developing full immunity against delta.

The results of research published July 21 in the New England Journal of Medicine show that after a dose of either vaccine, the estimated efficacy was lower against delta than against alpha, which prevailed previously. “After two doses, however, the efficacy of the vaccine was high,” the research said.

How do vaccines behave against the delta variant?

While public health experts have assured people that the immunity developed from vaccines protects individuals from catching the coronavirus delta mutation, the effectiveness of jabs appears to wane over time.

Of a number of vaccines developed around the world, Japan has so far only authorized Pfizer-BioNTech, Moderna and AstraZeneca-Oxford injections.

A recent major study by British researchers showed that the effectiveness of the Pfizer-BioNTech vaccine in preventing people from developing a high viral load due to delta was 92% 14 days after an individual received their second dose.

However, the effectiveness fell to 90% after 30 days, and then to 85% and 78% after 60 and 90 days, respectively. In the study, which was conducted by the University of Oxford and the local Office for National Statistics, researchers used PCR tests to detect the virus. The results were published in a preprinted version in the scientific journal Nature on August 19.

The same study showed that the results of tests carried out on samples from people inoculated with the vaccine developed by AstraZeneca PLC and the University of Oxford were 69% effective against a high viral load 14 days after the second dose, with a efficiency falling to 61% after 90 days.

Researchers analyzed the results of some 2.58 million tests for SARS-CoV-2 on 384,543 adults between December 1, 2020 and May 16, when the alpha variant first identified in the UK was dominant in many parts of the world. They compared the results with those based on 811,624 tests performed on 358,983 people between May 17 and August 1, a time when the delta variant was more dominant.

Of the three moves available in Japan, Moderna is perhaps the best against the Delta variant. There is some evidence that it may be as effective as 95% shortly after inoculation. On top of that, the results of a US pre-impression study of some 50,000 patients in Massachusetts showed that Moderna’s effectiveness increased from 86% in early 2021 to 76% in July. The study was conducted by the Mayo Clinic and clinical data analysis platform nference Inc. on the database from January through July. The results showed that the effectiveness of the Pfizer vaccine fell to 42% from 76% during the same period. The result was a significant drop in the protection against the 95% efficacy of the vaccine in clinical trials.

How do vaccines protect vaccinated people in the Delta?

Studies from the Delta suggest that people who have been vaccinated are much more likely to avoid hospitalization.

According to an American study published by Morbidity and Mortality Weekly Report, an epidemiological digest published in the United States by the CDC, the Moderna vaccine was 95% effective in preventing hospitalizations in adults 18 years and older. Meanwhile, the Pfizer vaccine was 80% effective and the Johnson & Johnson vaccine, which is not licensed for use in Japan, was only 60%.

A group of CDC researchers analyzed more than 32,000 medical encounters in nine states in June, July and August. The results showed that unvaccinated people with COVID-19 are 5 to 7 times more likely to need emergency care or hospitalization.

“The main goal of these vaccines is really to prevent serious illnesses because what we want for people, even if they do get the infection, is that they get over it and don’t get seriously ill. WHO Chief Scientist Soumya Swaminathan said in a statement. press release published on July 1. The Indian pediatrician, who is a world-renowned tuberculosis researcher, said the vaccine’s effectiveness in preventing hospital admissions was even over 90%. She explained that infection with the delta variant after inoculation would likely result in “very mild symptoms or no symptoms and the chances of getting seriously ill are really, really low.”

Vaccines have also been shown to be effective in preventing emergency care visits. Moderna was 92% effective, Pfizer was 77% effective, while Johnson & Johnson was 65% effective, according to the study.

Since the delta variant has become the dominant mutation in Japan, the government seems keen to follow countries like the United States in organizing vaccine boosts potentially by the end of the year to help improve the ‘immunity.

Are there vaccines developed specifically for the delta mutation?

Yes. German company BioNtech began clinical trials in August of a new type of vaccine targeting the delta variant. However, according to the company, even though vaccines can be produced in six weeks to 100 days, trials are currently being conducted for research purposes, as mRNA vaccines already in use have been shown to be effective against various coronavirus mutations, including delta.

The vaccine the company co-developed with Pfizer allows the body to make viral proteins in cells by injecting artificially produced mRNA, as opposed to vaccines that require the use of a real virus for development, a technique which was more common in the past.

But the company is still betting on improving immunity with a third dose of the existing vaccine.

Are there treatment options for delta infections?

On July 19, the Department of Health granted the world’s first regulatory approval for the use of Ronapreve, made by Chugai, for the treatment of mild to moderate symptoms of COVID-19. The move came amid an increase in delta infections and was the fourth treatment option introduced in Japan. But Ronapreve, in particular, raised hopes that he would prove effective against Delta.

In clinical trials, the drug effectively prevented symptoms from worsening after a single dose.

“In order to bring the pandemic under control as quickly as possible, it is extremely important to prevent new infections with vaccines and to expand treatment options for people with COVID-19,” said Osamu Okuda, chief executive officer from Chugai.

He explained that Ronapreve reduced the risk of hospitalization or death. He added that the therapy has been shown to be effective against several variants, including delta, in non-clinical studies.