Two Doses Of Pfizer Astrazeneca Shots Effective Against Delta Variant: Study
LONDON, July 21 – Two doses of Pfizer or AstraZeneca’s COVID-19 vaccine are nearly as effective against the highly transmissible Delta coronavirus variant as they are against the previously dominant Alpha variant, a study published on Wednesday showed.
Officials say vaccines are highly effective against the Delta variant, now the dominant variant worldwide, though the study reiterated that one shot of the vaccines is not enough for high protection.
The study, published in the New England Journal of Medicine, confirms headline findings given by Public Health England in May about the efficacy of COVID-19 vaccines made by Pfizer-BioNTech and Oxford-AstraZeneca , based on real-world data.
Wednesday’s study found that two doses of Pfizer’s shot was 88% effective at preventing symptomatic disease from the Delta variant, compared to 93.7% against the Alpha variant, broadly the same as previously reported.
Two shots of AstraZeneca vaccine were 67% effective against the Delta variant, up from 60% originally reported, and 74.5% effective against the Alpha variant, compared to an original estimate of 66% effectiveness.
“Only modest differences in vaccine effectiveness were noted with the Delta variant as compared with the Alpha variant after the receipt of two vaccine doses,” Public Health England researchers wrote in the study.
PHE had previously said that a first dose of either vaccine was around 33% effective against symptomatic disease from the Delta variant.
Vaccines Prevent Hospitalization And Death
Our understanding of how well shots stack up against Delta is changing with time, which is why the chart above lists large ranges for some types of protection. Research completed in the spring suggested a higher level of vaccine protection against Delta than the data from the last few months.
More comprehensive data is available for Pfizer and AstraZeneca, because public-health agencies in Israel and the UK where these shots dominate are constantly surveilling clinical outcomes among their populations.
A May analysis from Public Health England found that Pfizer’s and AstraZeneca’s vaccines were 88% and 60% effective in preventing symptomatic COVID-19, respectively. However, a study from Israel using data collected in June and July found that two Pfizer doses were only 64% effective at preventing infection and symptomatic illness.
Both of these studies, though, found that the vaccines were more than 90% effective in preventing hospitalization. And the Israeli data found Pfizer’s shot to be 93% effective against severe disease.
The vaccines from Moderna and Johnson & Johnson showed similarly strong performance against the worst outcomes associated with Delta, though the shots are less studied thus far.
In the last month, the average number of new daily cases in the US has more than quadrupled, from about 32,300 on July 18 to 140,900 on Wednesday. About 99.5% of new cases are among the unvaccinated.
Classification Of Infections By Variant Type
Viral genome sequencing and multiplex RTqPCR were used to screen for variants in randomly collected positive clinical samples,,,,, supplemented by deep wastewater sequencing,. The latter is used to compare the distribution of variants in wastewater to that in clinical samples collected from patients with SARS-CoV-2.
Ascertainment of Delta and Beta cases in this study was through weekly RTqPCR genotyping of positive clinical samples,. From 23 March 2021 to 7 September 2021, RTqPCR genotyping identified 6,005 Beta -like cases, 3,658 Alpha -like cases, 7,218 other variant cases and 51 B.1.375-like or B.1.258-like cases in 16,932 randomly collected specimens,. Since RTqPCR genotyping started on 23 March 2021, the proportion of all diagnosed infections in Qatar that have been RTqPCR genotyped is 12.0%, with the proportion of infections genotyped increasing with time, especially in the summer of 2021.
RTqPCR genotyping accuracy was contrasted against results of Sanger sequencing of the receptor-binding domain of SARS-CoV-2 surface glycoprotein gene or by viral whole-genome sequencing on a Nanopore GridION sequencing device. From 236 random samples , PCR genotyping results for Alpha-like, Beta-like and other variants were in 88.8% , 99.5% and 100% agreement with the SARS-CoV-2 lineages assigned by sequencing.
Recommended Reading: Is Hpv Vaccine Mandatory In Texas
But I Got The One Dose Of The Moderna Vaccine Will That Protect Me
Moderna said this week that its vaccine which is very similar to the Pfizer shot is also highly effective against the Delta variant.
The company tested blood serum from eight fully vaccinated individuals and found a 2.1-fold reduction in the efficiency with which those people would fend off infection with the Delta variant. Again, given the legion of antibodies induced by the vaccine, this reduction should have little to no effect on the vaccines protection.
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.
Also Check: How Many People Got Vaccinated
Unvaccinated People Are At Risk
People who have not been fully vaccinated against COVID-19 are most 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. .
Kids and young people are a concern as well. A recent 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. And so far, no vaccine has been approved for children 5 to 12 in the U.S., although the U.S. and a number of other countries have either authorized vaccines for adolescents and young children or are considering them.
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.
Vaccines 90% Effective Against Adult Deaths
In the most recent results of the UK observational study, a team led by a University of Edinburgh researcher estimated the odds of COVID-19 death among 114,706 vaccinated and unvaccinated Scottish adults who tested positive for COVID-19 from Apr 1 to Aug 16, 2021, and were followed up until Sep 27.
Vaccinees had received one or two doses of the Pfizer/BioNTech or AstraZeneca/Oxford COVID-19 vaccines. Relative to the vaccinated, unvaccinated adults tended to be much younger, have fewer chronic conditions, have lower socioeconomic status, and be men. Whole-genome sequencing showed that nearly all infections were caused by Delta.
Of 201 total COVID-19 deaths, none occurred among the 7,180 fully vaccinated participants 16 to 39 years old, compared with 17 among the 35,449 unvaccinated participants in that age-group . Of participants aged 40 to 59, 33 deaths occurred among the 4,803 unvaccinated participants , versus 18 among 12,905 in the fully vaccinated group .
Overall effectiveness against death from Delta infections at least 14 days after the second vaccine dose was 90% for Pfizer and 91% for AstraZeneca.
Among 40- to 59-year-olds, the vaccines were 88% effective against death for AstraZeneca and 95% for Pfizer. Overall effectiveness against death was 90% with AstraZeneca and 87% with Pfizer among those 60 years and older.
“If you still have not taken up your offer to be vaccinated, I would encourage you to do so based on the clear benefits it offers.”
You May Like: Is The Meningitis Vaccine Required For College
The Mrna Jabs Seem Bestbut All Offer Protection
THE RESULTS OF the first trial that showed that a vaccine could prevent symptomatic cases of covid-19, in November 2020, were greeted by the media with delight. As Nature put it: It works!. But the emergence of variants of SARS-CoV-2, the virus that causes covid, complicated the picture, since vaccines may work well against one variant, but not against another. Understanding the shots effectiveness against Delta, the variant that is now globally dominant, is a pressing concern.
What We Know So Far About Waning Vaccine Effectiveness
- 974
As tens of millions who are eligible in the United States consider signing up for a Covid-19 booster shot, a growing body of early global research shows that the vaccines authorized in the United States remain highly protective against the diseases worst outcomes over time, with some exceptions among older people and those with weakened immune systems.
But while the vaccines effectiveness against severe disease and hospitalization has mostly held steady, even through the summer surge of the highly transmissible Delta variant, a number of published studies show that their protection against infection, with or without symptoms, has fallen.
Public health experts say this decline does not mean that the vaccines are not working.
In fact, many studies show that the vaccines remain more than 50 percent effective at preventing infection, the level that all Covid vaccines had to meet or exceed to be back in 2020. But the significance of these declines in effectiveness and whether they suggest all adults should be eligible for a booster shot is still up for debate.
Effectiveness against symptomatic infection
Weeks since second dose
A study in England examined the vaccines effectiveness against the Delta variant over time. It found that the Pfizer-BioNTech vaccine is about 90 percent effective at preventing symptomatic infection two weeks after the second dose but drops to 70 percent effective after five months.
You May Like: What Vaccines Will My 2 Month Old Get
Pfizer Vaccine Very Effective Against Delta Variant In Adolescents In Israel
A vial of the Pfizer vaccine against the coronavirus disease is seen as medical staff are vaccinated at Sheba Medical Center in Ramat Gan, Israel December 19, 2020. REUTERS/Amir Cohen
JERUSALEM, Oct 21 – The Pfizer/BioNTech COVID-19 vaccine is highly effective at preventing infection and symptomatic disease from the Delta variant among 12- to 18-year-olds, research conducted in Israel shows.
The findings, published in the New England Journal of Medicine, will likely provide further reassurance the shot is effective against the variant among younger people as the U.S. drug watchdog considers authorising use of the vaccine on children as young as five.
The study found the estimated vaccine effectiveness against documented COVID-19 infection in adolescents was 90%, and 93% against symptomatic COVID-19, on days seven to 21 after the second dose.
Israel’s Clalit health maintenance organisation and Harvard University researchers reviewed data from 94,354 vaccine recipients aged 12 to 18 who were matched with an identical number of unvaccinated adolescents from the same age group.
The research was conducted between June and September, when the Delta variant was the main strain in Israel.
In a statement late on Wednesday, Clalit said the study was one of the largest peer-reviewed evaluations conducted among the age group of the effectiveness of the vaccine against the Delta variant.
A panel of advisers to the FDA is expected to weigh in on data on young children later this month.
There Is Still More To Learn About Delta
One important question is whether the Delta strain will make you sicker than the original virus. But many scientists say they dont know yet. Early information about the severity of Delta included a study from Scotland that showed the Delta variant was about twice as likely as Alpha to result in hospitalization in unvaccinated individuals, but other data has shown no significant difference.
Another question focuses on how Delta affects the body. There have been reports of symptoms that are different than those associated with the original coronavirus strain, Dr. Yildirim says. It seems like cough and loss of smell are less common. And headache, sore throat, runny nose, and fever are present based on the most recent surveys in the U.K., where more than 90% of the cases are due to the Delta strain, she says.
Experts are starting to learn more about Delta and breakthrough cases. A Public Health England analysis showed at least two vaccines to be effective against Delta. The Pfizer-BioNTech vaccine was 88% effective against symptomatic disease and 96% effective against hospitalization from Delta in the studies, while Oxford-AstraZeneca was 60% effective against symptomatic disease and 93% effective against hospitalization. The studies tracked participants who were fully vaccinated with both recommended doses.
Moderna also reported on studies that showed its vaccine to be effective against Delta and several other mutations .
Also Check: When Can I Have Pneumonia Vaccine
The Delta Variant Is Spreading Fast
The delta variant is the fast-moving form of the coronavirus that is now found in 96 countries, including the United States.
Last week, Dr. Anthony Fauci of the National Institutes of Health said the delta variant is “currently the greatest threat in the U.S. to our attempt to eliminate COVID-19,” noting that the proportion of infections being caused by the variant is doubling every two weeks.
How Effective Are Coronavirus Vaccines Against The Delta Variant
Follow how business and the economy are recovering post-pandemic with our Road to Recovery bulletin. Delivered 3 times a week.
As rising coronavirus infections force some countries to reimpose restrictions, scientists and drugmakers are racing to answer a crucial question: how well do the current vaccines protect against the Delta variant?
On one point, most observers agree. The leading shots, studies show, still offer strong protection against severe disease and hospitalisation.
Real-world effectiveness studies with a number of vaccines show good protection especially against severe disease, Soumya Swaminathan, chief scientist at the World Health Organization, told the Financial Times. The most important priority just now is to scale up vaccination coverage in all countries.
So called real-world analysis of 14,019 cases of the Delta variant in the UK, released by Public Health England in June, found the BioNTech/Pfizer and Oxford/AstraZeneca vaccines were, respectively, 96 per cent and 92 per cent effective against hospitalisation after two doses.
Late on Thursday, Pfizer reiterated it believed its shot worked against Delta, especially after a potential third booster dose. But it also added it planned to study a variant-targeted inoculation, with trials slated to start as early as next month.
But the question of whether the vaccines remain as effective at preventing infection, and therefore transmission and spread, is more fraught.
Recommended Reading: What Religions Are Against Vaccinations
Coronavirus Faq: I’ve Been Vaccinated Do I Need To Worry About Variants
“These new data are encouraging and reinforce our belief that the Moderna COVID-19 Vaccine should remain protective against newly detected variants,” Stéphane Bancel, Moderna’s chief executive officer, said in a statement. “These findings highlight the importance of continuing to vaccinate populations with an effective primary series vaccine.”
The company also said it is developing a booster candidate: a 50-50 mix of its currently authorized COVID-19 vaccine and another messenger RNA vaccine it has developed.
Vaccines More And More Effective Over The Months
The follow-up period only lasted five months, but over at least that time, researchers are confident that the vaccines are still effective. On the contrary: five months after receiving a second dose, the risk of being hospitalized is reduced by 94% compared to unvaccinated persons aged 75 and over, against 86% one month after the 14th day following the second injection. The same trend is observed in 50-74 year olds: one month after the second dose, those vaccinated with Pfizer, for example, have a 78% chance of avoiding hospitalization. This efficiency reaches 97% after five months.
You May Like: Who Qualifies For Pneumonia Vaccine
Astrazeneca As Powerful As The Others
Reputed to be less reliable to the point of being neglected in France and in many Western countries, the AstraZeneca vaccine appears to be as effective against severe forms as Pfizer and Moderna. These three play in the same court: beyond the 14th day after the second dose, the risk of being hospitalized decreases by 93% for the Pfizer vaccinees, 92% for the Moderna vaccinees and 94% for the vaccinees. AstraZeneca.
During the study period, researchers identified 26 deaths among those vaccinated Pfizer and 95 on the side of the unvaccinated, a risk reduction of 85% with this vaccine. No deaths were reported in the group vaccinated with Moderna or AstraZeneca.
However, the interpretation of the risk reduction for the AstraZeneca vaccine must be done with caution, qualify the authors of the study. First, the median follow-up of subjects who received this vaccine is shorter than that of subjects who received Pfizer or Moderna. Second, the analyzes presented in this report for this vaccine do not take into account that the second dose may be another vaccine. AstraZeneca will therefore be the subject of an in-depth study at a later date.
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.
Recommended Reading: When To Get Whooping Cough Vaccine While Pregnant