Are COVID vaccines becoming less effective?

Are COVID vaccines becoming less effective?

Juan Rodriguez (L) responds to receipt of the Janssen COVID-19 vaccine from Johnson & Johnson, administered by occupational nurse Christina Garibe during a community outreach program in Skid Row where COVID-19 occurs on August 22, 2021 in Los Angeles, California -19 vaccines and tests were offered.

Frederick J. Brown | AFP | Getty Images

Experts said COVID-19 vaccines were still “surprisingly effective,” despite fears immunity could wane over time.

There are concerns about the effectiveness of COVID-19 vaccines after several recent studies indicating a growing number of so-called “breakthrough” COVID cases among in-depth vaccinations. However, studies have shown that a full vaccination is still highly protected against serious infections, hospitalization and death from the virus.

Preliminary data released by the Israeli government It was discovered in July that the Pfizer vaccine was only 16% effective against symptomatic infections in people who received two doses in January. For those who were fully vaccinated in April, the vaccine was 79% effective against symptomatic infections, suggesting that the immunity gained from vaccination wanes over time.

Pfizer-funded research published in July showed that the efficacy of the Pfizer-BioNTech vaccine was highest between one week and two months after receiving the second dose, reaching 96.2%. However, it declined an average of 6% every two months. Four to six months after the second dose, its effectiveness has dropped to about 84%.

In August, meanwhile, a UK study of more than one million fully vaccinated people found that protection against the Oxford-AstraZeneca and Pfizer-BioNTech vaccines wore off over time. Analysis showed that one month after receiving the second dose of Pfizer vaccine, protection against the virus was 88%. After five to six months, this protection fell to 74%.

Protection was 77% one month after being fully vaccinated with the Oxford-AstraZeneca vaccine, and fell to 67% after four to five months.

lessons of israel

At the end of July, Israel began giving everyone over the age of 60 a third dose of the vaccine. Its booster program was quickly expanded and from August a third injection is available for all people over 30 in the country.

Professor Eyal Leshem, an infectious disease specialist at Sheba Medical Center who treats Covid patients in Israel, told CNBC that despite the high vaccination rate, cases are increasing, the rate of severe disease in the country is ” significantly low “.

“We attribute this to the fact that most of our adult population has been vaccinated with two doses, and over a million people have received a third booster dose,” he said on a phone call.

“The rate of severe illness in people vaccinated is about a tenth of that seen in unvaccinated people, which means the vaccine is still over 90% effective in preventing serious illness,” Leshem said. “People who receive booster doses also have a much lower risk of getting infected, our short-term data show.”

Richard Reithinger, infectious disease specialist and vice president of global health at US-based RTI International, told CNBC in an email that most vaccines developed for COVID-19 were “surprisingly effective even with new emerging forms “.

“The overwhelming proof of this is how dramatic reductions in cases, hospitalizations for serious illnesses and deaths have led to rapid increases in immunization coverage,” he said.

“Countries with very high immunization coverage, like Iceland with over 90%, rarely report serious cases and deaths. Likewise, in countries with moderate to high immunization coverage, such as the United States and Canada, severe cases and deaths are almost exclusively seen among the unconnected. “

delta effect

An earlier English study published in May found that the Pfizer-BioNTech vaccine was 88% more effective at preventing symptomatic disease than the delta variant. Against the alpha variant, once the dominant strain in the UK, the vaccine was 93% effective in preventing symptomatic disease.

Meanwhile, research found that two doses of the Oxford-AstraZeneca vaccine were 60% effective in preventing symptomatic disease of the delta version, compared to a 66% effectiveness rate compared to the alpha version.

The study found that the data showed the importance of taking two doses of these vaccines, because the effectiveness of the two injections against symptomatic delta variant infection was only 33% three weeks after the first dose.

Reithinger told CNBC that if the virus continued to mutate, that didn’t mean it would become more resistant to existing vaccines.

“The delta variant has been shown to be more transmissible than the other variants, and the vaccine’s efficacy is slightly lower than that of the alpha and beta variants. The kappa variant, which appeared at the same time in India, is however not transmissible, ”he said. Turn on the light.

Are booster shots the answer?

Several other countries, including the United States and the United Kingdom, are now offering – or planning to offer – a third dose of COVID-19 vaccines that help boost immunity to help reduce the virus. can do.

Booster shots may become a necessity, according to Professor Gideon Schreiber of the Weizmann Institute of Science in Israel.

“Unfortunately, it’s not even [going to be] Every year, this will happen twice a year, ”he predicted. “The virus has enormous potential for new forms, many of which will serve to suppress immunity – so there is a chance that we will need more boosters in the future.” “

Schreiber said Israel’s recall program has so far proven to be a huge success. After the second dose, he told CNBC, people were four or five times less likely to get seriously ill with Covid. But after the third dose, they were ten times less likely to get seriously ill with the virus.

However, Reithinger argued that the booster shots weren’t necessarily a logical decision at the time.

“There is only limited data available indicating that an immune response initiated by available vaccines appears to subside after six to eight months,” he told CNBC by email. “Most of the data is on infection rather than hospitalization or death. The data also does not account for the use of non-drug interventions, such as masking and social distancing, which must continue to be used and tracked in many settings. Unique Populations The group for which a case can be made for booster injections is that of the immunocompromised.

However, he added that booster shots may eventually be needed if the data shows that the effectiveness of vaccines against serious illness and death is reduced over time.

wait for treatment?

Schreiber is currently overseeing research into a therapeutic drug that would act like a “super cork,” physically blocking itself in the cell receptors to which the virus attaches. By working to block the “entry ports” of cells instead of attacking the virus, scientists hope to stay abreast of any future mutations.

“It should work against future variants because it doesn’t really attack the virus – the virus can change, but as long as the virus binds to it, it will block it,” he told CNBC.

Schreiber, however, said the drug would not be something that could be used on a large scale.

“It’s too expensive and it’s not necessary,” he said. “The way I see it is that it would be given to people who contracted COVID and were part of a high risk group. It does not have the same long term effects as the vaccine.

Leshem of Sheba Medical Center argued that vaccination was currently the best hope for society to find a state of “equilibrium” with the virus, where the virus could be transmitted without serious repercussions.

“The best hope for those at risk is vaccination, an effective vaccine, which we have now, and which can be improved by boosters, by mixing or by other means,” he said.

“Despite several [intense] Research, finding effective treatments is very difficult – viruses are not bacteria. So while we have developed some good antibiotics that drastically changed the course of bacterial infections, we don’t have as many good antivirals for many viruses that infect humans.

Besides vaccines, pharmaceutical companies are also considering new treatments to prevent Kovid. In mid-August, AstraZeneca released the results of a phase III antibody therapy trial, which was found to reduce the risk of developing symptomatic COVID-19 by 77%. There were no deaths or cases of serious illness among the 25 participants who contracted symptomatic COVID during the trial. A total of 5,172 people participated in the trial, of which 75% were co-morbid.

Reuters reported that AstraZeneca is seeking conditional approval for the therapy in key markets this year. The pharmaceutical giant will produce 1 to 2 million doses by the end of this year, the news agency said.

“I really believe we really need a drug,” Schreiber told CNBC. “There are many attempts at drug development, there is no reason to believe it will not happen in the near future. It will come and it will basically put, I think, the end of the story. “

He added: “The virus keeps changing – new versions will come, but the speed of technological advancement is truly amazing. This is why I say there is no reason to despair.



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