Two possible vaccines to protect against the new coronavirus, one from the University of Oxford and AstraZeneca Plc and the other from China's CanSino Biologics, induced immune responses in healthy volunteers without causing dangerous side effects, according to studies published Monday in The Lancet.
A third different type of vaccine from Pfizer Inc and German biotech BioNTech also showed promise in a small early study published Monday, raising hopes that at least one is safe and effective.
The following are five conclusions from Monday's developments, drawn in part from an editorial in The Lancet medical journal:
1. The teams from Oxford / AstraZeneca and CanSino published the results of the first trials of the COVID-19 vaccines that use harmless versions of another virus or viral vector, to deliver genetic material of the new coronavirus to the cells to generate an immune response. Both trials were primarily designed to assess the safety of vaccines and to provide possible evidence of efficacy. Subjects in both studies experienced mild side effects, such as fever and pain at the injection site, but no serious adverse events were reported. Vaccines are traditionally made using a weakened or inactivated form of the virus to provoke an immune response and prevent infection, but those vaccines are not easy to develop quickly. Viral vector vaccines do not need to be frozen, although they do need to be refrigerated. Johnson & Johnson's Ebola virus vaccine on July 1 became the first approved viral vector vaccine in Europe.
2. The COVID-19 pandemic has accelerated other new types of vaccine technology. The Pfizer-BioNTech candidate, who had initial data from a German study in 60 healthy volunteers, was shown to elicit an immune response and was well tolerated. The data was in line with that of another early-stage US trial published earlier this month. That vaccine uses a different novel platform, ribonucleic acid (RNA), the chemical messenger that contains instructions for cells to make proteins. RNA vaccines are designed to work by instructing cells to make proteins that mimic the surface of the coronavirus, which the body then sees as a foreign invader and learns to attack with an immune response. Although the technology has been around for years, there has never been an approved messenger RNA vaccine.
3. The number of people in whom experimental COVID-19 vaccines have been tested so far is small, but researchers say measurements of immune system responses are encouraging. Still, much is still unknown about COVID-19 vaccines in development, particularly the staying power of any immune response and effectiveness in older adults or other specific groups, including people with chronic health problems and more ethnic or racial groups. severely affected by the disease. Other outstanding questions include: Will a single dose suffice; Do they spur enough neutralizing antibodies and T cells, a type of white blood cell that helps the immune system destroy the infection; Do T cell responses correlate with longer term protection? Is there a chance that a vaccine could put someone at risk for a more serious infection?
4. More than 150 possible vaccines are being developed to prevent COVID-19. J&J is also developing a viral vector vaccine for the coronavirus and expects to start human trials this month. Last week Moderna Inc said its experimental RNA vaccine for COVID-19 showed it to be safe and elicited immune responses in the 45 healthy volunteers in an ongoing early-stage study. Moderna expects to start large-scale testing before the end of July. Once vaccines overcome early safety hurdles, they will need to be tested on thousands of subjects to ensure they can be safely administered to millions or billions of healthy people.
5. Studies published Monday bode well for those much larger, randomized trials to assess their efficacy and safety. AstraZeneca has ongoing late-stage trials in the United Kingdom, Brazil, and South Africa and aims to begin studies in the United States, where the prevalence of coronavirus is highest. Results can accumulate much more quickly in regions with high rates of active infection. AstraZeneca Chief Executive Pascal Soriot said the company expects the vaccine to be available this year, depending on how quickly late-stage trials can be completed, given the decline in the prevalence of the virus in Britain. While CanSino has yet to begin large-scale clinical trials to assess how well its vaccine prevents infection, it has been approved for use in the Chinese military. Pfizer and BioNTech have said they hope to start a trial later this month with up to 30,000 subjects with the goal of demonstrating the vaccine's effectiveness.
From NDTV News
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