Vaccines are declining protection against virus infection, CDC studies


The Centers for Disease Control and Prevention released three studies Wednesday that federal officials say provide evidence. Booster shots of Pfizer-BioNTech and Moderna coronavirus vaccines will be needed. by all Americans in the coming months.

But some experts said the new research doesn’t support the decision to recommend the booster shot for all Americans.

Taken together, studies show that while vaccines are highly effective against hospitalizations, the shield they provide against virus transmission has weakened over the past few months.

It is not clear whether the decline in protection against infection was the result of reduced immunity, reduced precautions such as wearing masks, or the highly contagious Delta variant, or a combination of the three.

General surgeon Dr. “We are concerned that this pattern of decline that we are seeing will continue in the coming months and that this could lead to reduced protection against hospitalizations and deaths due to serious illness,” Vivek Murthy said at a news briefing at the White House. Wednesday.

Citing the data, federal health officials devised a plan for Americans who received the two vaccines to have booster vaccines starting September 20, eight months after receiving their second dose.

Some scientists were deeply skeptical of the new plan.

D., an infectious disease specialist at Bellevue Hospital Center and a former pandemic counselor to management. “These data support the administration of additional doses of the vaccine to the highly immunocompromised and nursing home residents, not the general population,” said Celine Gounder.

Boosters said they would only be warranted if the vaccines failed to prevent people from being hospitalized with Covid-19.

Dr. “Feeling sick like a dog and lying in bed but not being in the hospital with severe Covid is not a good enough reason,” Gounder said. “We will be better protected by vaccinating the unvaccinated here and around the world.”

It’s unclear whether a third dose will help people who don’t have a strong response to the first two doses, said Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health.

Advice for boosters could also shake confidence in vaccines, he warned: “A third shot will raise skepticism among people who have not yet received a dose that the vaccines helped them with.”

Together, new studies show that overall, vaccines have an efficacy of roughly 55 percent against infections, 80 percent against symptomatic infection, and 90 percent or higher against hospitalization, said Ellie Murray, an epidemiologist at Boston University.

Dr. “These numbers are actually very good,” Murray said. “The only group where this data would suggest boosters for me are those who are immunocompromised.”

He added that the decline in protection against infection may be the result of increased exposure to a highly contagious species during a period of unrestrained social interactions: “This seems like a real possibility to me, because many of those who were vaccinated early were motivated by the desire to see friends and family and get back to normal.”

Dr. Murray said that boosters will undoubtedly boost immunity in an individual, but the benefit may be minimal and also easily achieved by wearing masks or avoiding indoor dining and crowded bars.

He and other experts said the administration’s emphasis on vaccines undermines the importance of taking other measures into people’s lives in comfortable and sustainable ways and building capacity for testing.

“That’s one reason why I think the administration’s focus on vaccines is so detrimental to morale,” he added. “We probably won’t be back to normal anytime soon.”

Before people begin taking booster supplements, the Food and Drug Administration must first approve the third dose of mRNA vaccines made by Pfizer-BioNTech and Moderna, and an advisory committee of the CDC should review the evidence and make recommendations.

One of the new CDC studies analyzed the effectiveness of the vaccines among approximately 4,000 nursing home residents between March 1 and May 9 before the Delta variant emerged, and among approximately 15,000 nursing home residents between June 21 and August 1, when the variant dominated new infections. in the country.

The effectiveness of vaccines in preventing infections fell from about 75 percent to 53 percent between these dates, study found. It did not evaluate the protection of vaccines against serious diseases.

Dr. Murray said nursing homes should only report the number of vaccinated residents after June 6, which “makes comparisons over time very difficult”. “It’s entirely possible that the vaccine efficacy reported here has not actually decreased over time.”

Dr. Gounder said the drop in activity could also be due to the spread of the Delta variant.

“It makes sense to give vaccinated nursing home residents an extra dose of the vaccine, but what will have a greater impact in protecting nursing home residents is to vaccinate their caregivers,” he said. Many health aides in long-term care facilities go unvaccinated.

a second study Evaluated data from New York State from May 3 to July 25, represents more than 80 percent of new cases when the Delta variant grows. The study found that during this time, the effectiveness of vaccines in preventing cases in adults dropped from 91.7 percent to 79.8 percent. But vaccines continued to be equally effective at preventing hospitalizations.

In those weeks, New York recorded 9,675 breakthrough infections (about 20 percent of total cases in the state) and 1,271 hospitalizations for vaccinated people, accounting for 15 percent of all Covid-19 hospitalizations.

Although fully vaccinated people of all ages are infected with the virus, vaccine efficacy fell most sharply, from 90.6 percent to 74.6 percent, in people aged 18 to 49 — often the people least likely to take precautions and most likely to socialize. .

Data from Israel suggested that immunity to infection was reduced in vaccinated adults aged 65 and over. But in the New York data, the efficacy of vaccines in this group remained virtually unchanged.

Adults aged 65 and over were more likely to be hospitalized than other age groups, regardless of immunization status. However, the vaccines did not show a decrease in efficacy against hospitalizations in any age group.

CDC’s third study showed 90 percent effectiveness against hospitalizations in the countryDr. “Which is excellent,” Gounder said.

Vaccines were less protective against hospitalization in immunocompromised persons. Dr. “But not all immunocompromised people will respond to an additional dose of vaccine,” said Gounder.

He added that everyone around them should be vaccinated and continue to wear masks to protect these vulnerable individuals.

Vaccines may appear less effective than they are in clinical trials because the experiments were done before the highly contagious Delta variant appeared. Vaccines may lose their effectiveness as more unvaccinated people become infected and acquire natural immunity.

Dr. Gounder said that if the goal is to prevent infection, it would be wiser to recommend a nasal spray vaccine supplement, which is better at inducing immunity in the nose and throat where the virus enters.


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