AstraZeneca announced in a press release on Monday that its COVID-19 vaccine has shown positive results in the interim analysis of clinical trial data.
This announcement marks the third vaccine to demonstrate strong efficacy in late-stage trials against the epidemic coronavirus, SARS-Covy-2. However, the effectiveness of the AstraZeneca vaccine is not as high as that of the previous vaccine.
Overall, the news raises optimism that effective vaccines could end the global crisis in the coming year.
Vaccine and its data
AstraZeneca partnered with researchers at Zxford University to develop a viral vector-based vaccine called AZD1222 (also called CADXXN NCOV-19). The vaccine involves coding the genetic material delivered to the body by a relatively benign virus for the infamous SARS-Co-2 spike protein. In this case, the virus is a weaker type of adenovirus – a pathogen that can cause colds and other mild infections in humans and some animals. The adenovirus used is one that primarily infects chimpanzees. When the adenovirus package delivers the code for the SARS-CoV-2 spike protein, the immune system can train to recognize and destroy anything from that same spike protein – and it will all be SARS-CoV-2 viral particles, which is with the spike protein studded.
The AZD1222 results released today came from a pool analysis of clinical trials conducted in the United Kingdom and Brazil, involving more than 23,000 participants. The independent monitoring board of AstraZeneca found that AZD1222 is on average about 70 percent effective in preventing the disease, Covid-19, caused by SARS-Cov-2. Interim analysis was stimulated when 131 cases were shown in trial participants who received a two-dose or comparator vaccine of AZD1222, the meningococcal vaccine MNXW. The effectiveness rate is calculated based on how the AZD 1222 group versus the 131 cases were divided into the MNXW group.
But the results were a little more complicated than that simple split. Participants receiving AZD1222 received one of the dosing resins, so the results were further split. In one method, participants were given half a dose of AZD1222, followed by a booster shot with the full dose. In trials, 2,741 participants found this lifestyle, and it appeared to be about 90 percent effective in preventing COVID-19.
In another method, participants receiving AZD1222 received two full doses of the vaccine. In other words, they got the same high dose level in the first shot as their booster shot. In the trial, 8,895 participants found this lifestyle, and it appeared to be about 62 percent effective in preventing COVID-19.
The pooled effectiveness data yields about 70 percent of the average effectiveness. This is impressive, with a target of about 50 percent. However, it is not as high as the spectacular mRNA vaccine efficacy results reported last week. This includes 95% efficacy for Pfizer / Bioentech vaccines and 94.5% efficacy for Moderna.
Unexpected Results
The good results of AstraZeneca with a lifestyle starting with a half dose have caused itching in the head among experts. Most importantly, it is unclear whether 90% of the effectiveness will capture the result as AstraZeneca collects more data and analyzes more. We do not yet know how 131 cases are subdivided into subgroup analyzes. The final effectiveness number is likely to change as more information is collected. But, if it doesn’t catch the discovery, some experts have begun to speculate as to why.
Some believe it may be down to adenovirus packaging. Although this vaccine is intended to stimulate immune responses against the SARS-Covy-2 spike protein driven by the adenovirus, some immune responses will inevitably attack the adenovirus. If the two-dose method starts better, it can help boost the immune system towards a stronger anti-adenovirus response rather than an anti-spike response when it delivers a booster shot. This is speculative, and much more data will be needed to understand what is really happening.
On a positive note, the need for less vaccines in the first dose – if that really ends up being the case – means more people can be vaccinated with the same vaccine production capacity.
And yet another positive – on a very early note, Ox Xford researchers reported that AZD1222 appeared to reduce asymptomatic infections with SARS-Cavi-2. Preliminary analysis looked at cases of symptoms of COVID-19, but some participants in the trial were routinely screened for asymptomatic infections. This finding is particularly eyebrow-raising because mRNA vaccine tests only look at symptomatic COVID-19 cases. However, the search is very early because the researchers did not present any data on it.
Safety
Like the mRNA vaccine, AstraZeneca said no serious adverse events related to the vaccine have been confirmed. In previous trial results, mild side effects of AZD1222 were common, including pain, fever, nausea, muscle aches, headaches, and nausea. To mitigate these effects, some participants were given paracetamol (acetaminophen / tylenol) in advance.
If you recall, AstraZeneca suspended its tests at least twice, once in July and once in September, for standard safety reviews. Tests were suspended in July when UK participants showed neurological symptoms in July and were later diagnosed with multiple sclerosis. In September, another participant developed symptoms in the line of transverse mellitus – a condition associated with inflammation of the spine, which, rarely, can be associated with vaccination. Eventually both cases were deemed unrelated to the vaccine and the trial resumed.
Otherwise, no hospitalization or serious cases of COVID-19 have been reported.
Delivery
A significant advantage of the adrenovirus vaccine of AstraZeneca is that the product is relatively easy to make and does not require special storage conditions. Compared to mRNA-based vaccines, adenovirus vectors are more established in the vaccine field, which is new. Production capacity for large quantities of adenovirus already exists.
AstraZeneca noted in its press release that it is making rapid progress in production with a capacity of up to 3 billion doses of the vaccine by 2021 on a rolling basis, with regulatory approval pending. The vaccine can be stored and administered in normal refrigerated conditions (2-8 સે C / 36-46 ફેર F) for at least six months and administered in existing healthcare settings. “
The mRNA vaccine requires cooling storage conditions. Most notably, the problematic -70 ° C for Pfizer and Bioentech vaccines. In a recent press release, Pfizer insisted that the companies had developed specially designed, temperature-controlled thermal shippers using dry ice to maintain temperatures of -70 ° C to 10 C. Can be used for days. ”The vaccine can be stored for 5 days in normal refrigerated 2-8 ° C conditions.
Pfizer and Bioentech aim to have 50 million vaccine doses globally by 2020 and 1.3 billion doses by the end of 2021.
Moderna announced in a recent press release that its vaccine can be frozen for six months at -40 ° C (-4 ° F) for 30 days at normal refrigerator temperatures (2-8 સે C or 2-8 સે C). Is, and at room temperature for up to 12 hours. Moderna is currently in the U.S. in 2020. It plans to take about 20 million doses of MRNA-1273 to send in and will produce an additional 500 million to 1 billion doses globally in 2021.
All three vaccines have now led regulators worldwide for authentication. Pfizer on Friday Submitted his request for Emergency Use Authorization from the Food and Drug Administration.
Strangers
While all three vaccines have yet to publish their complete datasets, there has been much uncertainty about the data and analysis. The number of effectiveness probably. Will change as the trial continues, safety oversight lengthens, and peer reviewers focus on analysis. Its rare side effects are also more likely to pop up over time.
While preliminary studies of the vaccine suggest that they ask participants for different types of immune responses, it is completely unknown how long any of these vaccines can last. It is still unclear whether the level of immune responses is the same for complete protection against infection or serious disease. In a year-old epidemic, a brand new-to-us pathogen, it is impossible to say with certainty how long those protective immune responses will be protective.
Finally, there is no data yet on how vaccines protect against asymptomatic infections. Disease prevention – and especially fatal disease – is the first priority in these tests. However, preventing asymptomatic or mild infections is the key to ending overall SARS-COV-2 transmission.
