COVID Roundup: ‘Breakthrough’ Cases are Milder, Shorter; Pfizer Vaccine vs. Variants; and Hospitalizations Among Adolescents

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June 11, 2021


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CDC: Milder, Shorter Illness for Few Who Get Infected After Being Vaccinated

The mRNA COVID-19 vaccines — from Pfizer-BioNTech and Moderna — make illness “milder and shorter” for the few vaccinated people who may still get infected, according to the U.S. Centers for Disease Control and Prevention.

A new update of an ongoing CDC study finds that vaccines reduce the risk of infection by 91 percent for fully vaccinated people. “This adds to the growing body of real-world evidence of their effectiveness,” the CDC states.

The study is also the first to show that mRNA vaccination benefits people who get COVID-19 despite being fully vaccinated (14 or more days after dose 2) or partially vaccinated (14 or more days after dose 1 to 13 days after dose 2). These are known as “breakthrough” infections.

“COVID-19 vaccines are a critical tool in overcoming this pandemic,” said CDC Director Rochelle P. Walensky, M.D., in a statement. “Findings from the extended timeframe of this study add to accumulating evidence that mRNA COVID-19 vaccines are effective and should prevent most infections — but that fully vaccinated people who still get COVID-19 are likely to have milder, shorter illness and appear to be less likely to spread the virus to others. These benefits are another important reason to get vaccinated.”

The findings are based on four weeks of additional data collected as part of the CDC’s HEROES-RECOVER study of healthcare workers, first responders, frontline workers, and other essential workers. These groups are more likely to be exposed to COVID-19 because of their occupations. Preliminary results from this study were first announced in March 2021.

In the new analysis, 3,975 participants completed weekly COVID-19 testing for 17 consecutive weeks (from December 13, 2020 to April 10, 2021) in eight U.S. locations. So far, about 5 percent have tested positive for coronavirus.

Those with breakthrough infections after one or two doses of the vaccines had about 40 percent less virus and were nearly 60 percent less likely to have fever, the CDC said. Overall, they spent two fewer days in bed compared to unvaccinated COVID-19 patients.


Report: 2 doses of Pfizer Vaccine Provides More Protection Against Variants in Lab Study

New research published in the medical journal, The Lancet, found two doses of Pfizer-BioNTech’s vaccine are “critical for protection” against emerging strains of COVID-19.

Researchers from the Francis Crick Institute and the National Institute for Health Research (NIHR) said the Pfizer-BioNTech vaccine was effective to some degree in a lab experiment against five coronavirus variants.

Most significantly, they pointed out, antibody response was “significantly lower” after one dose of the vaccine against the Delta variant first found in India, compared to the Alpha variant first found in the United Kingdom. The UK’s Alpha variant has been the most common variant detected in the U.S. thus far. 

“Although a single dose might still afford considerably more protection than no vaccination, single-dose recipients are likely to be less protected against COVID-19 variants (the Delta variant from India and the Beta variant from South Africa),” researchers said.

Overall, researchers tested the Pfizer vaccine against five variants: the original virus, an un-named variant currently detected in the U.K., the Delta variant first seen in India, the Beta variant first detect in South Africa, and the Alpha variant first found in the U.K.

The scientists examined the level of antibodies in blood samples of study participants who had received Pfizer’s shot. They then injected the participants with the variants. Prior to that, 149 volunteers had received a single dose, on average 30 days before, and about 159 had two doses 28 days before.

They found that the antibody response against the Alpha variant, first found in the U.K., was about two times lower, compared with the original virus. The antibody response was up to eight times lower against the Delta variant first detected in India.

However, researchers stress that the lab tests did not determine how much protection Pfizer’s vaccine will provide in real life against the variants — or how much the vaccine reduces the risk of severe illness or hospitalization from the variants.


CDC: ‘Troubling’ Increase in COVID Hospitalizations Among Adolescents Aged 12-17

Most COVID-19-related hospitalizations occur in adults, but severe disease can hit all age groups, including adolescents aged 12–17 years. Although hospitalizations among teens remain rare, there has been a “troubling” increase detected in this young age group, according to the U.S. Centers for Disease Control and Prevention (CDC). 

A new report from the CDC involved more than 200 adolescents who were hospitalized for COVID-19 across 14 states from January to the end of March. Of those 12-17-year-olds, more than 31 percent were admitted to an intensive care unit. And nearly 5 percent required a ventilator. No deaths were reported in the group.

The CDC states that COVID-19 adolescent hospitalization rates from COVID-19 peaked at 2.1 per 100,000 in early January 2021, and declined to 0.6 in mid-March. But hospitalization rates rose to 1.3 per 100,000 in April.

What are the implications of this report? The CDC says it merely confirms the need to vaccinate adolescents. On May 10, 2021, the U.S. Food and Drug Administration expanded the Emergency Use Authorization for Pfizer-BioNTech COVID-19 vaccine to include persons aged 12–15 years. The CDC’s Advisory Committee on Immunization Practices recommended it for this age group on May 12, 2021.

CDC Director Rochelle Walensky, M.D., called the hospitalization data “troubling” during a press conference.

“In the month leading up to the recommendations of the Pfizer COVID-19 vaccines for teens and adolescents 12 and older, CDC observed troubling data regarding the hospitalizations of adolescents with COVID-19,” she said. “More concerning were the number of adolescents admitted to the hospital who required treatment in the intensive care unit with mechanical ventilation.”

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