Low Protection After 1 Dose
One dose of either vaccine conferred much lower protection against Delta than Alpha .
But two doses of either vaccine were much more effective against both strains . Two doses of the Pfizer vaccine were 88.0% effective against Delta, compared with 93.7% against Alpha. The AstraZeneca vaccine was 67.0% effective against Delta and 74.5% effective against Alpha after two doses.
“We found that the absolute difference in vaccine effectiveness against symptomatic disease with one dose of vaccine with the delta variant as compared with the alpha variant was approximately 12 to 19 percentage points,” the study authors wrote. “However, the differences in vaccine effectiveness after two doses were small.”
The researchers noted that both vaccines were highly effective against both Delta and Alpha after two doses but that effectiveness against either variant was smaller among AstraZeneca recipients than those given Pfizer. They added that the numbers of cases and follow-up periods in the study were not sufficient to allow estimation of vaccine effectiveness against hospitalization or death.
“Overall, we found high levels of vaccine effectiveness against symptomatic disease with the delta variant after the receipt of two doses,” the authors said. “These estimates were only modestly lower than the estimate of vaccine effectiveness against the alpha variant.”
Uk Study: Pfizer 88% Effective Astrazeneca 67%
A UK-based study from May, published in the New England Journal of Medicine on July 21, found that two doses of either AstraZeneca or Pfizer’s vaccine were highly effective against the Delta variant, from two weeks after the second dose.
Pfizer
- 33% effective after one dose, 88% effective after two.
AstraZeneca
- 33% effective after one dose, 67% effective after two.
Unvaccinated People Are At Risk
In the U.S., there is a disproportionate number of unvaccinated people in Southern and Appalachian states including Alabama, Arkansas, Georgia, Mississippi, Missouri, and West Virginia, where vaccination rates are low, but cases are rising in other parts of the country as well. In September, health leaders in Idaho, which has one of the lowest vaccination rates in the country, expanded health care rationing throughout the state after the Delta surge led to a scarcity of resources for all hospitalized patients.
Children, teenagers, and young adults are a concern, too. A study from the United Kingdom showed that children and adults under 50 were 2.5 times more likely to become infected with Delta, says Dr. Yildirim. The U.S. has allowed Pfizer-BioNTech vaccinations for adolescents and teenagers since May, and, in early November, the CDC approved FDA authorization of the Pfizer vaccine for children ages 5-17.
As older age groups get vaccinated, those who are younger and unvaccinated will be at higher risk of getting COVID-19 with any variant, says Dr. Yildirim. But Delta seems to be impacting younger age groups more than previous variants.
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Latest Coronavirus News As Of Midday 13 April
More than 500 million covid-19 cases have been recorded globally since the outbreak emerged, but the true number is probably far higher
According to Johns Hopkins Universitys case tracker, more than 500,900,000 covid-19 cases have been reported worldwide. The World Health Organisation tracker, which updates daily, is just shy of this grim milestone, reporting 497,960,492 cases as of 12 April.
Experts have warned a lack of testing infrastructure worldwide means the global case number is probably much higher than is being reported, particularly in poorer countries. A WHO analysis estimates Africas true case number is 100 times higher than that which is being reported.
And unaccounted cases are expected to become more common as countries scale back their test capacity, for example in the UK.
The number of new worldwide cases appears to have been falling in recent weeks, with the daily case rate 41 per cent lower than it was two weeks ago, according to Johns Hopkins University. Reduced testing and a subsequent underreporting of cases probably contributed to this apparent fall in cases.
Tedros Adhanom Ghebreyesus at the WHO has warned we are still in an acute phase of the pandemic, as the more transmissible omicron variant and its sublineages spread across the world.
Other coronavirus news
Doctors are investigating what could be causing a surge in liver inflammation, or hepatitis, in children in the UK, after 74 cases have been reported so far this year.
Pfizer 93% Effective Against Symptomatic Infection In Teens
In Israel, the Clalit Research Institute, in conjunction with Harvard University, conducted an observational study involving 130,464 COVID-19naïve adolescents aged 12 to 18 years, half of whom were vaccinated with the Pfizer COVID-19 vaccine from Jun 8 to Sep 14, 2021 matched participants were unvaccinated. During the study, 13,423 unvaccinated participants were vaccinated.
At the time of the study, Delta was responsible for more than 95% of new infections in Israel. The study is the largest peer-reviewed look at COVID-19 vaccine efficacy among adolescents in a nationwide setting and the first such study conducted at a time when Delta was the dominant circulating strain.
Over a median of 27 days after receipt of the first vaccine dose, Kaplan-Meier curves for infection showed a similar incidence of infection in the first few days after the vaccinated group received their first dose, after which the rise in incidence slowed among the vaccinated.
Estimated effectiveness of the Pfizer vaccine against infection was 59% 14 to 20 days after the first dose, climbing to 66% on days 21 to 27 and 90% 7 to 21 days after the second dose.
Efficacy against symptomatic COVID-19 was estimated at 57% 14 to 20 days after the first vaccine dose, rising to 82% on days 21 to 27 and to 93% 7 to 21 days after the second dose.
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The Economist has collected what is possibly the largest set of vaccine results against the Delta variant, in terms of hospitalisation and symptomatic infection. We looked at results from a host of real-world and phase-three clinical trials of vaccines approved by American and European regulators, such as those made by AstraZeneca and Moderna, as well as shots made elsewhere in the world, including by Chinas Sinovac and Sinopharm, Indias Bharat Biotech, which makes Covaxin, and the Russian vaccine, Sputnik V. Our comparison is not perfect. Differences might arise from variations in the conduct of trials or the rates at which immunity wanes for different jabs. Vaccines whose trials were conducted later after they had been administered, or on more vulnerable populations, might appear worse than similarly protective jabs.
We found that vaccines continue to provide significant protection against symptomatic infection with the Delta variantall surpassed the 50% minimum threshold recommended by the World Health Organisation. And they provided even better protection against hospitalisation. But some results are more impressive than others.
These findings have implications for the trajectory of the pandemic. They make Chinas zero-covid strategy, for example, look even less tenable, since the two most widely used Chinese vaccines appear among the least effective at limiting transmission of the Delta variant.
Is The Delta Variant More Dangerous Than Previous Variants
As of now, there is no evidence that the Delta variant makes people more severely sick, but it is around twice as contagious as the original SARS-CoV-2 virus. This is in part because its better at hiding from the bodys immune system through mutations on the spike protein, which help it evade detection by the army of virus-fighting antibodies produced by the vaccine. It is also more contagious because people tend to carry around more particles of the virus in their nose and throat, making it easier to transmit to others. Finally, there is some evidence that it has a shorter incubation period, which means people get infected faster and so its harder to track cases before more infections occur.
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Study: Vaccines Still Effective Against Delta Variant
Obtaining two vaccine doses remains the most effective way to ensure protection against the COVID-19 delta variant of concern dominant in the UK today, according to a study from the University of Oxford.
Conducted in partnership with the Office of National Statistics and the Department for Health and Social Care , the study found that with delta, Pfizer-BioNTech and Oxford-AstraZeneca vaccines still offer good protection against new infections, but effectiveness is reduced compared with Alpha.
Two doses of either vaccine still provided at least the same level of protection as having had COVID-19 before through natural infection people who had been vaccinated after already being infected with COVID-19 had even more protection than vaccinated individuals who had not had COVID-19 before.
However, delta infections after two vaccine doses had similar peak levels of virus to those in unvaccinated people with the Alpha variant, peak virus levels in those infected post-vaccination were much lower.
Professor Sarah Walker, professor of medical statistics and epidemiology at the University of Oxford and chief investigator and academic lead for the COVID-19 Infection Survey, said: “We don’t yet know how much transmission can happen from people who get COVID-19 after being vaccinatedfor example, they may have high levels of virus for shorter periods of time.
Other key findings from the study:
About the National COVID-19 Infection Survey
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Older: Woman: Getting: Covid: Vax
A pair of new real-world COVID-19 vaccine studies show good protection against the Delta variant, one from Scotland finding higher than 90% effectiveness in preventing death in adults and the other showing 93% efficacy against symptomatic infection in Israeli adolescents after the second dose.
Both studies were published as letters today in the New England Journal of Medicine .
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Most People Need Booster Shots
While COVID-19 vaccines are effective, studies have shown some declines in vaccine effectiveness against infections over time, especially when the Delta variant was circulating widely. Everyone ages 18 and older should get a booster shot either 6 months after their initial Pfizer or Moderna series, or 2 months after their initial Johnson & Johnsons Janssen vaccine. People ages 1617 may get a booster dose of Pfizer at least 6 months after their initial series of vaccines.
How Effective Are The Vaccines Against The New Delta Variant
Data surrounding vaccine effectiveness with the Delta variant is so far limited.
While studies have shown that the available vaccines work against variants, including the Delta variant, all two-dose vaccines offer significantly more protection following their second dose.
Researchers in England studied how effective the two-dose AstraZeneca and Pfizer-BioNTech vaccines were against it, compared with the Alpha variant that was first detected in the U.K.
The vaccines were protective for those who got both doses but were less so among those who got one dose.
One recent study showed the Pfizer vaccine was 84% effective against the variant after two doses, but only 34% effective after the first dose.
Moderna also announced Tuesday that a new study showed its vaccine also produced promising protection in a lab setting against the Delta variant and others currently circulating.
As we seek to defeat the pandemic, it is imperative that we are proactive as the virus evolves. We remain committed to studying emerging variants, generating data and sharing it as it becomes available. These new data are encouraging and reinforce our belief that the Moderna COVID-19 Vaccine should remain protective against newly detected variants, Stéphane Bancel, chief executive officer of Moderna, said in a statement.
Dr. Scott Gottlieb, former Food and Drug Administration commissioner, reportedly said the Johnson & Johnson vaccine appears to be about 60% effective against the Delta variant.
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Vaccines Effective Against Most Sars
Two of the commonly used coronavirus vaccines provide protection against multiple variants of the virus that causes COVID-19, including the highly infectious Delta variant, a new Yale study has found.
The findings, , also show that those infected with the virus prior to vaccination exhibit a more robust immune response to all variants than those who were uninfected and fully vaccinated.
The results come as an increase in so-called breakthrough infections caused by the Delta variant among vaccinated individuals continues to raise questions about whether the vaccines offer broad protection against newly arising variants.
According to the researchers, the Moderna and Pfizer-BioNTech vaccines do bolster the immune systems response to infection.
Vaccines induce high levels of antibodies against Delta and most variants, said Akiko Iwasaki, the Waldemar Von Zedtwitz Professor of Immunobiology and co-corresponding author of the paper. And two shots are better than one.
In addition, the results suggest that booster shots can be effective in warding off SARS-CoV-2, the authors say.
The researchers then exposed the volunteers blood samples to 16 different SARS-COV-2 variants, including the Delta variant, the most predominant strain circulating in the United States, and then measured antibody and T cell response to each of the variants.
Other studies have also shown that vaccinated individuals tend to have less severe infections.
Vaccines Effective Against Delta Variant
COVID-19 vaccines are effectiveat preventing hospitalizations and emergency department visitscaused by the Delta variant, according to data from a national study.That data also indicate thatModernasvaccineis significantly more effective against Delta than Pfizer and Johnson & Johnson.
These real-world data show that vaccines remain highly effective at reducing COVID-19 related hospitalizations and emergency department visits, even in the presence of the new COVID-19 variant, said study author Shaun Grannis, M.D., M.S., Regenstrief Institute vice president for data and analytics and professor of medicine at Indiana University School of Medicine. We strongly recommend vaccinations for all who are eligible to reduce serious illness and ease the burden on our healthcare system.
The Centers for Disease Control and Prevention s VISION Network analyzed more than 32,000 medical encounters from nine states during June, July and August2021, whentheDelta variantbecamethe predominant strain. The results showed that unvaccinated individuals with COVID-19 are 5-7 times more likely to need emergency department care or hospitalization, similar to the overall effectiveness prior to the variant.
The studyinMorbidity and MortalityWeekly Reportisalso the first analysis from the VISION Network to show a marked difference between the effectiveness of the mRNA vaccines .In the studys time period:
Scientists say these findings need further monitoring and evaluation.
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A Third Dose Of Covid
Israel became the first country to widely administer an additional dose of COVID-19 vaccine for people at higher risk. Currently, people 60 or older can get a third dose of the Pfizer-BioNTech vaccine as a booster.
The Israeli Health Ministry said its decision was based on national health statistics, which suggested that people vaccinated in April appeared to have 75 percent protection against infection, while protection for people vaccinated in January dropped to as low as 16 percent.
Venky Soundararajan, PhD, who led the abovementioned Mayo Clinic study, said a Moderna booster shot is also in the works. It may be recommended for people who got the Pfizer-BioNTech or Moderna vaccines earlier this year.
Other countries, such as the United Kingdom, Spain, and Germany, have also approved third doses to be administered to people who do not mount a proper immune response after getting their initial two doses.
The United States is also one of them.
The CDC has so far only recommended a three-shot regimen to boost protection for immunocompromised people, such as organ transplant recipients and people with cancer, who received either the Pfizer-BioNTech or Moderna vaccine.
The United States also has a booster plan that would offer people either Pfizer-BioNTech or Moderna boosters 8 months after their second dose. The rollout is expected to start Sept. 20.
Moderna also said on Sept. 9 that its working on a single vaccine that combines both a COVID-19 booster dose and a flu shot.
Public Health England In Its Latest Risk Assessment Of The Variants Of The Coronavirus Has Stated That 61% Of The Sequenced Samples Are Of Delta Variant
Bengaluru : Public Health England in its latest risk assessment of the variants of the coronavirus has stated that 61% of the sequenced samples are of Delta variant.
In India most of the cases are from the Sublineage of double mutant – B.1.617.2 which was a new variant first found in India in December 20.
The Delta variant has been labelled as a Variant-Of-Concern by the WHO because it has significantly increased transmissibility.
Dr Vishal Rao, Dean, Centre for Academic Research, HCG Cancer Hospital remarked, “Had we picked the strain and mounted our response earlier, we could have saved more lives.” Rao stated that the second wave impact and fatalities is proof of the same.
A couple of days ago, Deputy Chief Minister C.N Ashwath Narayan discussed genomic surveillance of Covid strains with Dr Rao along with Dr Vamsi Veeramachaneni, chief scientific officer with Life Strand Sciences, and Rohan Pais, COO with Life Strand Sciences, following a report submitted by them on genomic surveillance of COVID patients from Bengaluru showing the new double mutant variant sub lineage B.1.617.2
Ashwath Narayan said that it was important to carry out genomic surveillance to identify emerging strains early so that scientists can establish the transmissibility rates of the new strains, assess vaccine protectiveness, verify RT-PCR kit performance, and study clinical presentation.
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Why The Numbers Vary
It becomes harder to measure how well vaccines work in the real world compared with trials, because you can’t control who gets vaccinated and who doesn’t. Other differences between the two groups could influence the risk of getting sick from COVID-19. For example, those who chose not to get vaccinated could also be more likely to put themselves in risky situations that may expose them to the virus.
The numbers can also vary because they depend on other factors, including what you’re measuring, when you measure it, the age of the population you’re measuring it in, and whether people have had previous COVID-19 infections.
Stephen Evans, professor of medical statistics at the London School of Hygiene & Tropical Medicine, told Insider that in general, the more severe the illness caused by Delta, the better the COVID-19 vaccines appeared to work against it. But the evidence on vaccines’ effectiveness wasn’t strong, he said.