Chloe Ramirez
The SARS-CoV-2 Delta variant (B.1.617.2) is the most infectious variant of the virus to date and has spread across the globe, causing a new wave of the COVID-19 epidemic. The high transmissibility, mortality, and morbidity rates of the Delta variant have raised concerns regarding vaccine effectiveness. While the effectiveness of the BNT162b2 (Pfizer) and ChAdOx1 nCoV-19 (AstraZeneca) vaccines against the Delta variant has been unclear, recent studies have shown that two doses of the Pfizer or AstraZeneca vaccines are nearly as effective against the Delta variant as they are against the previously dominant Alpha variant.
| Characteristics | Values |
|---|---|
| Effectiveness of AstraZeneca vaccine against the Delta variant | 44% effective after the first dose; 59.8% effective after two doses; 60% effective in preventing infection and reducing severity of illness and hospitalizations |
| Effectiveness of Pfizer-BioNTech vaccine against the Delta variant | 56.7% effective after the first dose; 87.9% effective after two doses; 79-88% effective in preventing infection and reducing severity of illness and hospitalizations |
| Effectiveness of Moderna vaccine against the Delta variant | 72% effective after the first dose; 83.7% effective after two doses; 97.2% effective after three doses |
| Effectiveness of CoronaVac vaccine against the Delta variant | 13.8% effective after the first dose; 44% effective after two doses |
| Effectiveness of Bharat Biotech vaccine against the Delta variant | Not found |
| Effectiveness of Novavax vaccine against the Delta variant | Not found |
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What You'll Learn
- Two doses of the AstraZeneca vaccine are 92% effective at preventing hospitalisation
- The vaccine is also highly effective against the Alpha variant
- The WHO recommends the AstraZeneca vaccine in countries where new variants are prevalent
- The vaccine is less effective at preventing infection with the Delta variant
- The vaccine is highly effective at preventing severe illness and death
Two doses of the AstraZeneca vaccine are 92% effective at preventing hospitalisation
The AstraZeneca vaccine has been found to be effective in preventing hospitalisation due to the Delta variant. Two doses of the AstraZeneca vaccine are 92% effective at preventing hospitalisation, according to data from Public Health England (PHE). The data included 14,019 cases of the Delta variant, 122 of whom were hospitalised, and showed no deaths among those vaccinated. The vaccine also showed a high level of effectiveness against the Alpha variant, with an 86% reduction in hospitalisations and no deaths reported.
The Delta variant is a highly transmissible variant of the SARS-CoV-2 virus that has contributed to a surge in cases globally. It has been characterised by several spike protein mutations that may affect immune responses. The high transmissibility and mortality rate of the Delta variant have raised concerns regarding vaccine effectiveness.
While the effectiveness of a single dose of the AstraZeneca vaccine against the Delta variant has been found to be reduced, two doses of the vaccine have been shown to provide high levels of protection. A study published in the New England Journal of Medicine found that two doses of the AstraZeneca vaccine were nearly as effective against the Delta variant as they were against the previously dominant Alpha variant. The study also showed that one shot of the vaccine was not enough for high protection.
The protective efficacy of existing vaccines against the Delta variant has been found to decline with the number of doses and the time since vaccination. However, vaccines are still effective in preventing hospitalisation and severe disease due to the Delta variant. Accelerating vaccination and improving the coverage rate are important measures to control the spread of the Delta variant.
Overall, while vaccine effectiveness against the Delta variant may be modestly lower than against other variants, two doses of the AstraZeneca vaccine provide high levels of protection against hospitalisation and severe disease.
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The vaccine is also highly effective against the Alpha variant
The AstraZeneca vaccine is highly effective against the Alpha variant. Real-world data from Public Health England (PHE) demonstrated that two doses of the AstraZeneca vaccine are 86% effective against hospitalisation due to the Alpha variant, with no deaths reported among those vaccinated. This is supported by recent data showing a strong T-cell response to the AstraZeneca vaccine, which should correlate with high and durable protection.
The Alpha variant, or B.1.1.7, was first identified in the United Kingdom and was the predominant lineage seen between January and May 2021. The AstraZeneca vaccine provides a high level of protection against this variant, with levels of protection similar to those observed in clinical trials. This includes additional protection against severe disease.
While the effectiveness of the AstraZeneca vaccine against the Delta variant has been a concern, the vaccine is still highly effective against the Alpha variant. The Alpha variant has been associated with increased transmissibility, mortality, and morbidity rates, and the AstraZeneca vaccine has been shown to provide strong protection against it.
The AstraZeneca vaccine has been found to be effective in preventing symptomatic disease caused by the Alpha variant. A study published in the New England Journal of Medicine found that two doses of the AstraZeneca vaccine were highly effective against symptomatic disease caused by the Alpha variant. This is consistent with reported clinical trial findings and provides further evidence of the vaccine's efficacy.
Overall, the AstraZeneca vaccine has demonstrated high levels of effectiveness against the Alpha variant, including protection against hospitalisation and severe disease. This highlights the importance of vaccination in preventing the spread of the Alpha variant and reducing the burden on healthcare systems.
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The WHO recommends the AstraZeneca vaccine in countries where new variants are prevalent
The World Health Organization (WHO) has recommended the use of the Oxford-AstraZeneca coronavirus vaccine even in countries where new variants are prevalent. The Strategic Advisory Group of Experts on Immunization (SAGE) panel noted that "preliminary analyses" showed that the AstraZeneca vaccine had reduced effectiveness against coronavirus variants that emerged in Britain and South Africa. However, they emphasized that there is no reason not to recommend its use, even in countries with circulating variants.
The AstraZeneca vaccine is important in the global fight against COVID-19, especially in countries with new variants. The vaccine is a crucial component of the COVAX Facility, a U.N.-backed initiative aiming to provide vaccines to people worldwide, regardless of a country's economic status. The ability to store the vaccine at refrigerator temperatures, rather than the colder temperatures required for the Pfizer-BioNTech vaccine, makes it more accessible for deployment in a variety of settings.
While South Africa initially paused its rollout of the AstraZeneca vaccine due to concerns about its effectiveness against the variant prevalent in the country, the WHO maintained its recommendation. The WHO's endorsement is based on the belief that the vaccine could help prevent severe infections and deaths, even if its protection capacity is reduced. The organization emphasized that a reduction in severe cases, hospitalizations, and deaths is the most critical outcome for early vaccine rollout.
Furthermore, real-world data from Public Health England (PHE) demonstrated that the AstraZeneca vaccine offers high levels of protection against the Delta variant (B.1.617.2). Two doses of the vaccine were found to be 92% effective against hospitalization due to the Delta variant, and no deaths were reported among those vaccinated. The vaccine also showed high effectiveness against the Alpha variant (B.1.1.7), with an 86% reduction in hospitalizations and no deaths.
In summary, the WHO recommends the AstraZeneca vaccine in countries with new variants, such as the Delta variant, as it can help prevent severe disease and reduce hospitalizations and deaths. While its effectiveness against certain variants may be reduced, the vaccine still offers a significant impact in combating the virus and saving lives.
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The vaccine is less effective at preventing infection with the Delta variant
Real-world data from different countries has shown that current vaccination procedures cannot prevent Delta variant infection and morbidity. However, the AstraZeneca vaccine is effective against hospitalisation and severe disease due to the Delta variant. Two doses of the AstraZeneca vaccine are 92% effective against hospitalisation due to the Delta variant, and no deaths have been reported among those vaccinated.
The Delta variant is more infectious than other variants of concern and has immune evasion characteristics. A higher proportion of the population needs to be vaccinated to reduce the disease burden. The WHO Strategic Advisory Group of Experts on Immunization (SAGE) has recommended the AstraZeneca vaccine in countries where new variants, like the Delta variant, are prevalent.
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The vaccine is highly effective at preventing severe illness and death
The AstraZeneca vaccine is highly effective at preventing severe illness and death. A study published in the New England Journal of Medicine found that two doses of the AstraZeneca vaccine were nearly as effective against the highly transmissible Delta variant as they were against the previously dominant Alpha variant. The study showed that two doses of the AstraZeneca vaccine were 59.8% effective at preventing symptomatic disease from the Delta variant, compared to 66.1% against the Alpha variant. This is supported by real-world data from Public Health England (PHE), which demonstrated that two doses of the AstraZeneca vaccine are 92% effective against hospitalization due to the Delta variant, and showed no deaths among those vaccinated.
The AstraZeneca vaccine is one of several COVID-19 vaccines that have been found to be effective against the Delta variant. Other vaccines that have been shown to be effective include the Pfizer-BioNTech, Moderna, Bharat Biotech, and CoronaVac vaccines. The effectiveness of these vaccines in preventing severe illness and death associated with the Delta variant is important in controlling the spread of the virus and reducing the burden on healthcare systems.
While the AstraZeneca vaccine has been shown to be highly effective at preventing severe illness and death, it is important to note that vaccine effectiveness is related to the number of doses and the time since vaccination. After the first dose, the vaccine effectiveness against the Delta variant was lower than that of the Alpha variant, at approximately 30-33%. However, after the second dose, vaccine effectiveness increased significantly, with only small reductions observed in protection against the Delta variant compared to the Alpha variant.
The Delta variant is the dominant variant in many countries and has raised concerns due to its high transmissibility, mortality, and morbidity rates. The high infectivity of the Delta variant means that a higher proportion of the population needs to be vaccinated to reduce the disease burden. Accelerating vaccination against COVID-19 and increasing vaccine coverage are important measures to prevent and control the spread of the Delta variant. In countries with high vaccination rates, such as the United Kingdom, the fatality rate has not increased with surging cases, highlighting the importance of vaccination in protecting against severe illness and death.
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Frequently asked questions
Yes, the AstraZeneca vaccine is effective against the Delta variant. Two doses of the AstraZeneca vaccine are nearly as effective against the highly transmissible Delta coronavirus variant as they are against the previously dominant Alpha variant.
The effectiveness of the AstraZeneca vaccine against the Delta variant is between 59.8% and 60%. The effectiveness of the vaccine is related to the number of doses and the time since vaccination.
Two doses of the AstraZeneca vaccine are required to achieve high levels of protection against the Delta variant. One dose of the AstraZeneca vaccine is around 30% effective against the Delta variant.
