Despite its advantages over other vaccine technologies for Covid-19, adenovirus vector vaccines are likely to be tripped up by pre-existing antibodies to the vectors used and the need for a second injection to boost protection.
CanSino Biologics’ Ad5-nCoV and Johnson & Johnson’s AdVac platform-based vaccine use a human adenovirus vector, but a significant chunk of people may already have neutralising antibodies against the vector, decreasing efficacy prospects. Phase I Ad5-nCoV data is also underwhelming, adding credence to the issue of pre-existing antibodies.
AstraZeneca’s AZD1222 and Rome-based ReiThera’s Covid-19 vaccines are also adenovirus vectored but use nonhuman vectors. However, AZD1222’s recent animal data also leave questions about its utility to prevent virus spread. A possible way to improve efficacy is to add a booster shot down the line, perhaps using a different adenovirus vector or even a different vaccine technology. Perhaps AZD1222 only carrying SARS-CoV-2’s spike protein may not be enough.
There are at least 38 companies or universities with a recombinant adenovirus-derived vaccine asset for Covid-19 from preclinical to Phase II/III stages, according to GlobalData. AstraZeneca partnered with Oxford University on 30 April to further develop AZD1222, and on 3 June, the US Federal Government’s vaccine initiative, Operation Warp Speed, named it as one of five finalists along with Johnson & Johnson’s (J&J) candidate. Phase I/II AZD1222 trial (NCT04324606) data are expected shortly, while J&J’s Phase I/IIa will start in July. ReiThera will also begin a clinical investigation in the summer. CanSino is the only company that has released clinical trial data, with Ad5-nCoV already in a Phase II trial (NCT04341389) that has a primary completion date of January 2021.
AZD1222 is concurrently in Phase II/III trial (NCT04400838), with data timelines dependent on community viral transmission rates, the Oxford University website states. A registrational field trial expected to start in the summer is likely to require around 25,000–30,000 volunteers if the annualised incidence rate is 1.5%, this news service reported on 14 May. While a challenge trial design could be considered to quickly gather protection data, such a trial design also has its own operational and ethical issues.
Image Credit: Envato/ Amanda Scott
News This Week
The University of Oxford, in collaboration with AstraZeneca plc, today announces interim trial data from its Phase III trials that show its candidate vaccine, ChAdOx1 nCoV-2019, is effective at preventing COVID-19 (SARS-CoV-2) and offers a [...]
A genetic modification in the ‘coat’ of a brain infection-causing virus may allow it to escape antibodies, according to Penn State College of Medicine researchers. They say testing people for this and other viral mutations [...]
Current chemotherapy regimens slow cancer progression and save lives, but these powerful drugs affect both healthy and cancerous cells. Now, researchers reporting in ACS' Nano Letters have designed DNA-based nanogels that only break down and [...]
The new technology behind Pfizer's and Moderna's coronavirus vaccines could be used to prevent everything from heart disease to cancer, experts say. The breakthrough vaccine 'platform' they use transforms the body into a virus-zapping vaccine [...]
Current state-of-the-art techniques have clear limitations when it comes to imaging the smallest nanoparticles, making it difficult for researchers to study viruses and other structures at the molecular level. Scientists from the University of Houston [...]
Virtual patients, vaccines, medicine-making biomachines and microneedles are examples of tech innovation that is meeting the moment to address the global health crisis. Health has been a strong focus for this year’s top 10 [...]
A Vancouver company is central to the news Monday morning that Pfizer is close to developing an effective vaccine against the coronavirus. Pfizer said Monday that an early peek at the data on its [...]
The first coronavirus vaccine can prevent more than 90% of people from getting Covid-19, a preliminary analysis shows. The developers - Pfizer and BioNTech - described it as a "great day for science and humanity". [...]
Researchers led by the University at Buffalo (UB) have devised a new method that could enhance the effectiveness of vaccines against the novel coronavirus, the virus that is responsible for causing COVID-19. Jonathan F. Lovell, PhD, an [...]
On March 17 this year, a man was taken to hospital in Israel suffering from a dry cough and a loss of sense of smell. He developed a fever and felt tired but, after three [...]
One of the world’s leading Covid-19 experimental vaccines produces an immune response in older adults as well as the young, its developers say, raising hopes of protection for those most vulnerable to the coronavirus that [...]
Coronavirus tests performed in labs are the gold standard for accuracy and antigen tests are a fast and inexpensive alternative. But backers of a third type of test, developed by a Nobel Prize winner [...]
COVID-19 is a severe infectious disease that has claimed >150,000 lives and infected millions in the United States thus far, especially the elderly population. Emerging evidence has shown the virus to cause hemorrhagic and immunologic [...]
Switzerland’s Covid-19 scientific taskforce chief says hospitals across the Alpine country could be swamped with new coronavirus cases in the next two or three weeks unless the situation improves. “We estimate that the capacity limit [...]
Scientists are to increase surveillance for new coronavirus mutations amid concerns that future strains of the virus could develop at least partial resistance to antibody treatments and Covid-19 vaccines. There is no evidence that the [...]